Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=625efab1cd3d4da4634dfe26df6b4005385397e2
Commit:     625efab1cd3d4da4634dfe26df6b4005385397e2
Parent:     56adbe9ddc935600c64635d6a55c260a63c67e4a
Author:     Jes Sorensen <[EMAIL PROTECTED]>
AuthorDate: Mon Oct 22 11:03:28 2007 +1000
Committer:  Rusty Russell <[EMAIL PROTECTED]>
CommitDate: Tue Oct 23 15:49:51 2007 +1000

    Move i386 part of core.c to x86/core.c.
    
    Separate i386 architecture specific from core.c and move it to
    x86/core.c and add x86/lguest.h header file to match.
    
    Signed-off-by: Jes Sorensen <[EMAIL PROTECTED]>
    Signed-off-by: Rusty Russell <[EMAIL PROTECTED]>
---
 arch/x86/lguest/boot.c                |    1 +
 drivers/lguest/Makefile               |    2 +-
 drivers/lguest/core.c                 |  459 +------------------------------
 drivers/lguest/interrupts_and_traps.c |   18 +-
 drivers/lguest/lg.h                   |   63 +----
 drivers/lguest/segments.c             |   26 +-
 drivers/lguest/x86/core.c             |  476 +++++++++++++++++++++++++++++++++
 drivers/lguest/x86/switcher_32.S      |    3 +-
 include/asm-x86/lguest.h              |   87 ++++++
 9 files changed, 613 insertions(+), 522 deletions(-)

diff --git a/arch/x86/lguest/boot.c b/arch/x86/lguest/boot.c
index 8e9e485..c7ebc13 100644
--- a/arch/x86/lguest/boot.c
+++ b/arch/x86/lguest/boot.c
@@ -65,6 +65,7 @@
 #include <asm/e820.h>
 #include <asm/mce.h>
 #include <asm/io.h>
+#include <asm/i387.h>
 
 /*G:010 Welcome to the Guest!
  *
diff --git a/drivers/lguest/Makefile b/drivers/lguest/Makefile
index a4567c9..d330f5b 100644
--- a/drivers/lguest/Makefile
+++ b/drivers/lguest/Makefile
@@ -6,7 +6,7 @@ obj-$(CONFIG_LGUEST)    += lg.o
 lg-y = core.o hypercalls.o page_tables.o interrupts_and_traps.o \
        segments.o io.o lguest_user.o
 
-lg-$(CONFIG_X86_32) += x86/switcher_32.o
+lg-$(CONFIG_X86_32) += x86/switcher_32.o x86/core.o
 
 Preparation Preparation!: PREFIX=P
 Guest: PREFIX=G
diff --git a/drivers/lguest/core.c b/drivers/lguest/core.c
index ca581ef..06869a2 100644
--- a/drivers/lguest/core.c
+++ b/drivers/lguest/core.c
@@ -11,54 +11,20 @@
 #include <linux/vmalloc.h>
 #include <linux/cpu.h>
 #include <linux/freezer.h>
+#include <linux/highmem.h>
 #include <asm/paravirt.h>
-#include <asm/desc.h>
 #include <asm/pgtable.h>
 #include <asm/uaccess.h>
 #include <asm/poll.h>
-#include <asm/highmem.h>
 #include <asm/asm-offsets.h>
-#include <asm/i387.h>
 #include "lg.h"
 
-/* Found in switcher.S */
-extern char start_switcher_text[], end_switcher_text[], switch_to_guest[];
-extern unsigned long default_idt_entries[];
-
-/* Every guest maps the core switcher code. */
-#define SHARED_SWITCHER_PAGES \
-       DIV_ROUND_UP(end_switcher_text - start_switcher_text, PAGE_SIZE)
-/* Pages for switcher itself, then two pages per cpu */
-#define TOTAL_SWITCHER_PAGES (SHARED_SWITCHER_PAGES + 2 * NR_CPUS)
-
-/* We map at -4M for ease of mapping into the guest (one PTE page). */
-#define SWITCHER_ADDR 0xFFC00000
 
 static struct vm_struct *switcher_vma;
 static struct page **switcher_page;
 
-static int cpu_had_pge;
-static struct {
-       unsigned long offset;
-       unsigned short segment;
-} lguest_entry;
-
 /* This One Big lock protects all inter-guest data structures. */
 DEFINE_MUTEX(lguest_lock);
-static DEFINE_PER_CPU(struct lguest *, last_guest);
-
-/* Offset from where switcher.S was compiled to where we've copied it */
-static unsigned long switcher_offset(void)
-{
-       return SWITCHER_ADDR - (unsigned long)start_switcher_text;
-}
-
-/* This cpu's struct lguest_pages. */
-static struct lguest_pages *lguest_pages(unsigned int cpu)
-{
-       return &(((struct lguest_pages *)
-                 (SWITCHER_ADDR + SHARED_SWITCHER_PAGES*PAGE_SIZE))[cpu]);
-}
 
 /*H:010 We need to set up the Switcher at a high virtual address.  Remember the
  * Switcher is a few hundred bytes of assembler code which actually changes the
@@ -69,9 +35,7 @@ static struct lguest_pages *lguest_pages(unsigned int cpu)
  * Host since it will be running as the switchover occurs.
  *
  * Trying to map memory at a particular address is an unusual thing to do, so
- * it's not a simple one-liner.  We also set up the per-cpu parts of the
- * Switcher here.
- */
+ * it's not a simple one-liner. */
 static __init int map_switcher(void)
 {
        int i, err;
@@ -128,90 +92,11 @@ static __init int map_switcher(void)
                goto free_vma;
        }
 
-       /* Now the switcher is mapped at the right address, we can't fail!
-        * Copy in the compiled-in Switcher code (from switcher.S). */
+       /* Now the Switcher is mapped at the right address, we can't fail!
+        * Copy in the compiled-in Switcher code (from <arch>_switcher.S). */
        memcpy(switcher_vma->addr, start_switcher_text,
               end_switcher_text - start_switcher_text);
 
-       /* Most of the switcher.S doesn't care that it's been moved; on Intel,
-        * jumps are relative, and it doesn't access any references to external
-        * code or data.
-        *
-        * The only exception is the interrupt handlers in switcher.S: their
-        * addresses are placed in a table (default_idt_entries), so we need to
-        * update the table with the new addresses.  switcher_offset() is a
-        * convenience function which returns the distance between the builtin
-        * switcher code and the high-mapped copy we just made. */
-       for (i = 0; i < IDT_ENTRIES; i++)
-               default_idt_entries[i] += switcher_offset();
-
-       /*
-        * Set up the Switcher's per-cpu areas.
-        *
-        * Each CPU gets two pages of its own within the high-mapped region
-        * (aka. "struct lguest_pages").  Much of this can be initialized now,
-        * but some depends on what Guest we are running (which is set up in
-        * copy_in_guest_info()).
-        */
-       for_each_possible_cpu(i) {
-               /* lguest_pages() returns this CPU's two pages. */
-               struct lguest_pages *pages = lguest_pages(i);
-               /* This is a convenience pointer to make the code fit one
-                * statement to a line. */
-               struct lguest_ro_state *state = &pages->state;
-
-               /* The Global Descriptor Table: the Host has a different one
-                * for each CPU.  We keep a descriptor for the GDT which says
-                * where it is and how big it is (the size is actually the last
-                * byte, not the size, hence the "-1"). */
-               state->host_gdt_desc.size = GDT_SIZE-1;
-               state->host_gdt_desc.address = (long)get_cpu_gdt_table(i);
-
-               /* All CPUs on the Host use the same Interrupt Descriptor
-                * Table, so we just use store_idt(), which gets this CPU's IDT
-                * descriptor. */
-               store_idt(&state->host_idt_desc);
-
-               /* The descriptors for the Guest's GDT and IDT can be filled
-                * out now, too.  We copy the GDT & IDT into ->guest_gdt and
-                * ->guest_idt before actually running the Guest. */
-               state->guest_idt_desc.size = sizeof(state->guest_idt)-1;
-               state->guest_idt_desc.address = (long)&state->guest_idt;
-               state->guest_gdt_desc.size = sizeof(state->guest_gdt)-1;
-               state->guest_gdt_desc.address = (long)&state->guest_gdt;
-
-               /* We know where we want the stack to be when the Guest enters
-                * the switcher: in pages->regs.  The stack grows upwards, so
-                * we start it at the end of that structure. */
-               state->guest_tss.esp0 = (long)(&pages->regs + 1);
-               /* And this is the GDT entry to use for the stack: we keep a
-                * couple of special LGUEST entries. */
-               state->guest_tss.ss0 = LGUEST_DS;
-
-               /* x86 can have a finegrained bitmap which indicates what I/O
-                * ports the process can use.  We set it to the end of our
-                * structure, meaning "none". */
-               state->guest_tss.io_bitmap_base = sizeof(state->guest_tss);
-
-               /* Some GDT entries are the same across all Guests, so we can
-                * set them up now. */
-               setup_default_gdt_entries(state);
-               /* Most IDT entries are the same for all Guests, too.*/
-               setup_default_idt_entries(state, default_idt_entries);
-
-               /* The Host needs to be able to use the LGUEST segments on this
-                * CPU, too, so put them in the Host GDT. */
-               get_cpu_gdt_table(i)[GDT_ENTRY_LGUEST_CS] = FULL_EXEC_SEGMENT;
-               get_cpu_gdt_table(i)[GDT_ENTRY_LGUEST_DS] = FULL_SEGMENT;
-       }
-
-       /* In the Switcher, we want the %cs segment register to use the
-        * LGUEST_CS GDT entry: we've put that in the Host and Guest GDTs, so
-        * it will be undisturbed when we switch.  To change %cs and jump we
-        * need this structure to feed to Intel's "lcall" instruction. */
-       lguest_entry.offset = (long)switch_to_guest + switcher_offset();
-       lguest_entry.segment = LGUEST_CS;
-
        printk(KERN_INFO "lguest: mapped switcher at %p\n",
               switcher_vma->addr);
        /* And we succeeded... */
@@ -243,80 +128,6 @@ static void unmap_switcher(void)
                __free_pages(switcher_page[i], 0);
 }
 
-/*H:130 Our Guest is usually so well behaved; it never tries to do things it
- * isn't allowed to.  Unfortunately, Linux's paravirtual infrastructure isn't
- * quite complete, because it doesn't contain replacements for the Intel I/O
- * instructions.  As a result, the Guest sometimes fumbles across one during
- * the boot process as it probes for various things which are usually attached
- * to a PC.
- *
- * When the Guest uses one of these instructions, we get trap #13 (General
- * Protection Fault) and come here.  We see if it's one of those troublesome
- * instructions and skip over it.  We return true if we did. */
-static int emulate_insn(struct lguest *lg)
-{
-       u8 insn;
-       unsigned int insnlen = 0, in = 0, shift = 0;
-       /* The eip contains the *virtual* address of the Guest's instruction:
-        * guest_pa just subtracts the Guest's page_offset. */
-       unsigned long physaddr = guest_pa(lg, lg->regs->eip);
-
-       /* The guest_pa() function only works for Guest kernel addresses, but
-        * that's all we're trying to do anyway. */
-       if (lg->regs->eip < lg->page_offset)
-               return 0;
-
-       /* Decoding x86 instructions is icky. */
-       lgread(lg, &insn, physaddr, 1);
-
-       /* 0x66 is an "operand prefix".  It means it's using the upper 16 bits
-          of the eax register. */
-       if (insn == 0x66) {
-               shift = 16;
-               /* The instruction is 1 byte so far, read the next byte. */
-               insnlen = 1;
-               lgread(lg, &insn, physaddr + insnlen, 1);
-       }
-
-       /* We can ignore the lower bit for the moment and decode the 4 opcodes
-        * we need to emulate. */
-       switch (insn & 0xFE) {
-       case 0xE4: /* in     <next byte>,%al */
-               insnlen += 2;
-               in = 1;
-               break;
-       case 0xEC: /* in     (%dx),%al */
-               insnlen += 1;
-               in = 1;
-               break;
-       case 0xE6: /* out    %al,<next byte> */
-               insnlen += 2;
-               break;
-       case 0xEE: /* out    %al,(%dx) */
-               insnlen += 1;
-               break;
-       default:
-               /* OK, we don't know what this is, can't emulate. */
-               return 0;
-       }
-
-       /* If it was an "IN" instruction, they expect the result to be read
-        * into %eax, so we change %eax.  We always return all-ones, which
-        * traditionally means "there's nothing there". */
-       if (in) {
-               /* Lower bit tells is whether it's a 16 or 32 bit access */
-               if (insn & 0x1)
-                       lg->regs->eax = 0xFFFFFFFF;
-               else
-                       lg->regs->eax |= (0xFFFF << shift);
-       }
-       /* Finally, we've "done" the instruction, so move past it. */
-       lg->regs->eip += insnlen;
-       /* Success! */
-       return 1;
-}
-/*:*/
-
 /*L:305
  * Dealing With Guest Memory.
  *
@@ -380,104 +191,6 @@ void lgwrite(struct lguest *lg, unsigned long addr, const 
void *b,
 }
 /* (end of memory access helper routines) :*/
 
-static void set_ts(void)
-{
-       u32 cr0;
-
-       cr0 = read_cr0();
-       if (!(cr0 & 8))
-               write_cr0(cr0|8);
-}
-
-/*S:010
- * We are getting close to the Switcher.
- *
- * Remember that each CPU has two pages which are visible to the Guest when it
- * runs on that CPU.  This has to contain the state for that Guest: we copy the
- * state in just before we run the Guest.
- *
- * Each Guest has "changed" flags which indicate what has changed in the Guest
- * since it last ran.  We saw this set in interrupts_and_traps.c and
- * segments.c.
- */
-static void copy_in_guest_info(struct lguest *lg, struct lguest_pages *pages)
-{
-       /* Copying all this data can be quite expensive.  We usually run the
-        * same Guest we ran last time (and that Guest hasn't run anywhere else
-        * meanwhile).  If that's not the case, we pretend everything in the
-        * Guest has changed. */
-       if (__get_cpu_var(last_guest) != lg || lg->last_pages != pages) {
-               __get_cpu_var(last_guest) = lg;
-               lg->last_pages = pages;
-               lg->changed = CHANGED_ALL;
-       }
-
-       /* These copies are pretty cheap, so we do them unconditionally: */
-       /* Save the current Host top-level page directory. */
-       pages->state.host_cr3 = __pa(current->mm->pgd);
-       /* Set up the Guest's page tables to see this CPU's pages (and no
-        * other CPU's pages). */
-       map_switcher_in_guest(lg, pages);
-       /* Set up the two "TSS" members which tell the CPU what stack to use
-        * for traps which do directly into the Guest (ie. traps at privilege
-        * level 1). */
-       pages->state.guest_tss.esp1 = lg->esp1;
-       pages->state.guest_tss.ss1 = lg->ss1;
-
-       /* Copy direct-to-Guest trap entries. */
-       if (lg->changed & CHANGED_IDT)
-               copy_traps(lg, pages->state.guest_idt, default_idt_entries);
-
-       /* Copy all GDT entries which the Guest can change. */
-       if (lg->changed & CHANGED_GDT)
-               copy_gdt(lg, pages->state.guest_gdt);
-       /* If only the TLS entries have changed, copy them. */
-       else if (lg->changed & CHANGED_GDT_TLS)
-               copy_gdt_tls(lg, pages->state.guest_gdt);
-
-       /* Mark the Guest as unchanged for next time. */
-       lg->changed = 0;
-}
-
-/* Finally: the code to actually call into the Switcher to run the Guest. */
-static void run_guest_once(struct lguest *lg, struct lguest_pages *pages)
-{
-       /* This is a dummy value we need for GCC's sake. */
-       unsigned int clobber;
-
-       /* Copy the guest-specific information into this CPU's "struct
-        * lguest_pages". */
-       copy_in_guest_info(lg, pages);
-
-       /* Set the trap number to 256 (impossible value).  If we fault while
-        * switching to the Guest (bad segment registers or bug), this will
-        * cause us to abort the Guest. */
-       lg->regs->trapnum = 256;
-
-       /* Now: we push the "eflags" register on the stack, then do an "lcall".
-        * This is how we change from using the kernel code segment to using
-        * the dedicated lguest code segment, as well as jumping into the
-        * Switcher.
-        *
-        * The lcall also pushes the old code segment (KERNEL_CS) onto the
-        * stack, then the address of this call.  This stack layout happens to
-        * exactly match the stack of an interrupt... */
-       asm volatile("pushf; lcall *lguest_entry"
-                    /* This is how we tell GCC that %eax ("a") and %ebx ("b")
-                     * are changed by this routine.  The "=" means output. */
-                    : "=a"(clobber), "=b"(clobber)
-                    /* %eax contains the pages pointer.  ("0" refers to the
-                     * 0-th argument above, ie "a").  %ebx contains the
-                     * physical address of the Guest's top-level page
-                     * directory. */
-                    : "0"(pages), "1"(__pa(lg->pgdirs[lg->pgdidx].pgdir))
-                    /* We tell gcc that all these registers could change,
-                     * which means we don't have to save and restore them in
-                     * the Switcher. */
-                    : "memory", "%edx", "%ecx", "%edi", "%esi");
-}
-/*:*/
-
 /*H:030 Let's jump straight to the the main loop which runs the Guest.
  * Remember, this is called by the Launcher reading /dev/lguest, and we keep
  * going around and around until something interesting happens. */
@@ -485,11 +198,6 @@ int run_guest(struct lguest *lg, unsigned long __user 
*user)
 {
        /* We stop running once the Guest is dead. */
        while (!lg->dead) {
-               /* We need to initialize this, otherwise gcc complains.  It's
-                * not (yet) clever enough to see that it's initialized when we
-                * need it. */
-               unsigned int cr2 = 0; /* Damn gcc */
-
                /* First we run any hypercalls the Guest wants done: either in
                 * the hypercall ring in "struct lguest_data", or directly by
                 * using int 31 (LGUEST_TRAP_ENTRY). */
@@ -538,132 +246,20 @@ int run_guest(struct lguest *lg, unsigned long __user 
*user)
                 * the "Do Not Disturb" sign: */
                local_irq_disable();
 
-               /* Remember the awfully-named TS bit?  If the Guest has asked
-                * to set it we set it now, so we can trap and pass that trap
-                * to the Guest if it uses the FPU. */
-               if (lg->ts)
-                       set_ts();
-
-               /* SYSENTER is an optimized way of doing system calls.  We
-                * can't allow it because it always jumps to privilege level 0.
-                * A normal Guest won't try it because we don't advertise it in
-                * CPUID, but a malicious Guest (or malicious Guest userspace
-                * program) could, so we tell the CPU to disable it before
-                * running the Guest. */
-               if (boot_cpu_has(X86_FEATURE_SEP))
-                       wrmsr(MSR_IA32_SYSENTER_CS, 0, 0);
-
-               /* Now we actually run the Guest.  It will pop back out when
-                * something interesting happens, and we can examine its
-                * registers to see what it was doing. */
-               run_guest_once(lg, lguest_pages(raw_smp_processor_id()));
-
-               /* The "regs" pointer contains two extra entries which are not
-                * really registers: a trap number which says what interrupt or
-                * trap made the switcher code come back, and an error code
-                * which some traps set.  */
-
-               /* If the Guest page faulted, then the cr2 register will tell
-                * us the bad virtual address.  We have to grab this now,
-                * because once we re-enable interrupts an interrupt could
-                * fault and thus overwrite cr2, or we could even move off to a
-                * different CPU. */
-               if (lg->regs->trapnum == 14)
-                       cr2 = read_cr2();
-               /* Similarly, if we took a trap because the Guest used the FPU,
-                * we have to restore the FPU it expects to see. */
-               else if (lg->regs->trapnum == 7)
-                       math_state_restore();
-
-               /* Restore SYSENTER if it's supposed to be on. */
-               if (boot_cpu_has(X86_FEATURE_SEP))
-                       wrmsr(MSR_IA32_SYSENTER_CS, __KERNEL_CS, 0);
+               /* Actually run the Guest until something happens. */
+               lguest_arch_run_guest(lg);
 
                /* Now we're ready to be interrupted or moved to other CPUs */
                local_irq_enable();
 
-               /* OK, so what happened? */
-               switch (lg->regs->trapnum) {
-               case 13: /* We've intercepted a GPF. */
-                       /* Check if this was one of those annoying IN or OUT
-                        * instructions which we need to emulate.  If so, we
-                        * just go back into the Guest after we've done it. */
-                       if (lg->regs->errcode == 0) {
-                               if (emulate_insn(lg))
-                                       continue;
-                       }
-                       break;
-               case 14: /* We've intercepted a page fault. */
-                       /* The Guest accessed a virtual address that wasn't
-                        * mapped.  This happens a lot: we don't actually set
-                        * up most of the page tables for the Guest at all when
-                        * we start: as it runs it asks for more and more, and
-                        * we set them up as required. In this case, we don't
-                        * even tell the Guest that the fault happened.
-                        *
-                        * The errcode tells whether this was a read or a
-                        * write, and whether kernel or userspace code. */
-                       if (demand_page(lg, cr2, lg->regs->errcode))
-                               continue;
-
-                       /* OK, it's really not there (or not OK): the Guest
-                        * needs to know.  We write out the cr2 value so it
-                        * knows where the fault occurred.
-                        *
-                        * Note that if the Guest were really messed up, this
-                        * could happen before it's done the INITIALIZE
-                        * hypercall, so lg->lguest_data will be NULL */
-                       if (lg->lguest_data
-                           && put_user(cr2, &lg->lguest_data->cr2))
-                               kill_guest(lg, "Writing cr2");
-                       break;
-               case 7: /* We've intercepted a Device Not Available fault. */
-                       /* If the Guest doesn't want to know, we already
-                        * restored the Floating Point Unit, so we just
-                        * continue without telling it. */
-                       if (!lg->ts)
-                               continue;
-                       break;
-               case 32 ... 255:
-                       /* These values mean a real interrupt occurred, in
-                        * which case the Host handler has already been run.
-                        * We just do a friendly check if another process
-                        * should now be run, then fall through to loop
-                        * around: */
-                       cond_resched();
-               case LGUEST_TRAP_ENTRY: /* Handled at top of loop */
-                       continue;
-               }
-
-               /* If we get here, it's a trap the Guest wants to know
-                * about. */
-               if (deliver_trap(lg, lg->regs->trapnum))
-                       continue;
-
-               /* If the Guest doesn't have a handler (either it hasn't
-                * registered any yet, or it's one of the faults we don't let
-                * it handle), it dies with a cryptic error message. */
-               kill_guest(lg, "unhandled trap %li at %#lx (%#lx)",
-                          lg->regs->trapnum, lg->regs->eip,
-                          lg->regs->trapnum == 14 ? cr2 : lg->regs->errcode);
+               /* Now we deal with whatever happened to the Guest. */
+               lguest_arch_handle_trap(lg);
        }
+
        /* The Guest is dead => "No such file or directory" */
        return -ENOENT;
 }
 
-/* Now we can look at each of the routines this calls, in increasing order of
- * complexity: do_hypercalls(), emulate_insn(), maybe_do_interrupt(),
- * deliver_trap() and demand_page().  After all those, we'll be ready to
- * examine the Switcher, and our philosophical understanding of the Host/Guest
- * duality will be complete. :*/
-static void adjust_pge(void *on)
-{
-       if (on)
-               write_cr4(read_cr4() | X86_CR4_PGE);
-       else
-               write_cr4(read_cr4() & ~X86_CR4_PGE);
-}
-
 /*H:000
  * Welcome to the Host!
  *
@@ -705,31 +301,8 @@ static int __init init(void)
                return err;
        }
 
-       /* Finally, we need to turn off "Page Global Enable".  PGE is an
-        * optimization where page table entries are specially marked to show
-        * they never change.  The Host kernel marks all the kernel pages this
-        * way because it's always present, even when userspace is running.
-        *
-        * Lguest breaks this: unbeknownst to the rest of the Host kernel, we
-        * switch to the Guest kernel.  If you don't disable this on all CPUs,
-        * you'll get really weird bugs that you'll chase for two days.
-        *
-        * I used to turn PGE off every time we switched to the Guest and back
-        * on when we return, but that slowed the Switcher down noticibly. */
-
-       /* We don't need the complexity of CPUs coming and going while we're
-        * doing this. */
-       lock_cpu_hotplug();
-       if (cpu_has_pge) { /* We have a broader idea of "global". */
-               /* Remember that this was originally set (for cleanup). */
-               cpu_had_pge = 1;
-               /* adjust_pge is a helper function which sets or unsets the PGE
-                * bit on its CPU, depending on the argument (0 == unset). */
-               on_each_cpu(adjust_pge, (void *)0, 0, 1);
-               /* Turn off the feature in the global feature set. */
-               clear_bit(X86_FEATURE_PGE, boot_cpu_data.x86_capability);
-       }
-       unlock_cpu_hotplug();
+       /* Finally we do some architecture-specific setup. */
+       lguest_arch_host_init();
 
        /* All good! */
        return 0;
@@ -742,15 +315,9 @@ static void __exit fini(void)
        free_pagetables();
        unmap_switcher();
 
-       /* If we had PGE before we started, turn it back on now. */
-       lock_cpu_hotplug();
-       if (cpu_had_pge) {
-               set_bit(X86_FEATURE_PGE, boot_cpu_data.x86_capability);
-               /* adjust_pge's argument "1" means set PGE. */
-               on_each_cpu(adjust_pge, (void *)1, 0, 1);
-       }
-       unlock_cpu_hotplug();
+       lguest_arch_host_fini();
 }
+/*:*/
 
 /* The Host side of lguest can be a module.  This is a nice way for people to
  * play with it.  */
diff --git a/drivers/lguest/interrupts_and_traps.c 
b/drivers/lguest/interrupts_and_traps.c
index 0dfb090..fdefc0a 100644
--- a/drivers/lguest/interrupts_and_traps.c
+++ b/drivers/lguest/interrupts_and_traps.c
@@ -165,7 +165,7 @@ void maybe_do_interrupt(struct lguest *lg)
        /* Look at the IDT entry the Guest gave us for this interrupt.  The
         * first 32 (FIRST_EXTERNAL_VECTOR) entries are for traps, so we skip
         * over them. */
-       idt = &lg->idt[FIRST_EXTERNAL_VECTOR+irq];
+       idt = &lg->arch.idt[FIRST_EXTERNAL_VECTOR+irq];
        /* If they don't have a handler (yet?), we just ignore it */
        if (idt_present(idt->a, idt->b)) {
                /* OK, mark it no longer pending and deliver it. */
@@ -197,14 +197,14 @@ int deliver_trap(struct lguest *lg, unsigned int num)
 {
        /* Trap numbers are always 8 bit, but we set an impossible trap number
         * for traps inside the Switcher, so check that here. */
-       if (num >= ARRAY_SIZE(lg->idt))
+       if (num >= ARRAY_SIZE(lg->arch.idt))
                return 0;
 
        /* Early on the Guest hasn't set the IDT entries (or maybe it put a
         * bogus one in): if we fail here, the Guest will be killed. */
-       if (!idt_present(lg->idt[num].a, lg->idt[num].b))
+       if (!idt_present(lg->arch.idt[num].a, lg->arch.idt[num].b))
                return 0;
-       set_guest_interrupt(lg, lg->idt[num].a, lg->idt[num].b, has_err(num));
+       set_guest_interrupt(lg, lg->arch.idt[num].a, lg->arch.idt[num].b, 
has_err(num));
        return 1;
 }
 
@@ -341,10 +341,10 @@ void load_guest_idt_entry(struct lguest *lg, unsigned int 
num, u32 lo, u32 hi)
        lg->changed |= CHANGED_IDT;
 
        /* Check that the Guest doesn't try to step outside the bounds. */
-       if (num >= ARRAY_SIZE(lg->idt))
+       if (num >= ARRAY_SIZE(lg->arch.idt))
                kill_guest(lg, "Setting idt entry %u", num);
        else
-               set_trap(lg, &lg->idt[num], num, lo, hi);
+               set_trap(lg, &lg->arch.idt[num], num, lo, hi);
 }
 
 /* The default entry for each interrupt points into the Switcher routines which
@@ -387,7 +387,7 @@ void copy_traps(const struct lguest *lg, struct desc_struct 
*idt,
 
        /* We can simply copy the direct traps, otherwise we use the default
         * ones in the Switcher: they will return to the Host. */
-       for (i = 0; i < ARRAY_SIZE(lg->idt); i++) {
+       for (i = 0; i < ARRAY_SIZE(lg->arch.idt); i++) {
                /* If no Guest can ever override this trap, leave it alone. */
                if (!direct_trap(i))
                        continue;
@@ -396,8 +396,8 @@ void copy_traps(const struct lguest *lg, struct desc_struct 
*idt,
                 * Interrupt gates (type 14) disable interrupts as they are
                 * entered, which we never let the Guest do.  Not present
                 * entries (type 0x0) also can't go direct, of course. */
-               if (idt_type(lg->idt[i].a, lg->idt[i].b) == 0xF)
-                       idt[i] = lg->idt[i];
+               if (idt_type(lg->arch.idt[i].a, lg->arch.idt[i].b) == 0xF)
+                       idt[i] = lg->arch.idt[i];
                else
                        /* Reset it to the default. */
                        default_idt_entry(&idt[i], i, def[i]);
diff --git a/drivers/lguest/lg.h b/drivers/lguest/lg.h
index c1ca127..203d310 100644
--- a/drivers/lguest/lg.h
+++ b/drivers/lguest/lg.h
@@ -1,13 +1,6 @@
 #ifndef _LGUEST_H
 #define _LGUEST_H
 
-#include <asm/desc.h>
-
-#define GDT_ENTRY_LGUEST_CS    10
-#define GDT_ENTRY_LGUEST_DS    11
-#define LGUEST_CS              (GDT_ENTRY_LGUEST_CS * 8)
-#define LGUEST_DS              (GDT_ENTRY_LGUEST_DS * 8)
-
 #ifndef __ASSEMBLY__
 #include <linux/types.h>
 #include <linux/init.h>
@@ -18,34 +11,12 @@
 #include <linux/wait.h>
 #include <linux/err.h>
 #include <asm/semaphore.h>
-#include "irq_vectors.h"
-
-#define GUEST_PL 1
 
-struct lguest_regs
-{
-       /* Manually saved part. */
-       unsigned long ebx, ecx, edx;
-       unsigned long esi, edi, ebp;
-       unsigned long gs;
-       unsigned long eax;
-       unsigned long fs, ds, es;
-       unsigned long trapnum, errcode;
-       /* Trap pushed part */
-       unsigned long eip;
-       unsigned long cs;
-       unsigned long eflags;
-       unsigned long esp;
-       unsigned long ss;
-};
+#include <asm/lguest.h>
 
 void free_pagetables(void);
 int init_pagetables(struct page **switcher_page, unsigned int pages);
 
-/* Full 4G segment descriptors, suitable for CS and DS. */
-#define FULL_EXEC_SEGMENT ((struct desc_struct){0x0000ffff, 0x00cf9b00})
-#define FULL_SEGMENT ((struct desc_struct){0x0000ffff, 0x00cf9300})
-
 struct lguest_dma_info
 {
        struct list_head list;
@@ -98,23 +69,6 @@ struct pgdir
        spgd_t *pgdir;
 };
 
-/* This is a guest-specific page (mapped ro) into the guest. */
-struct lguest_ro_state
-{
-       /* Host information we need to restore when we switch back. */
-       u32 host_cr3;
-       struct Xgt_desc_struct host_idt_desc;
-       struct Xgt_desc_struct host_gdt_desc;
-       u32 host_sp;
-
-       /* Fields which are used when guest is running. */
-       struct Xgt_desc_struct guest_idt_desc;
-       struct Xgt_desc_struct guest_gdt_desc;
-       struct i386_hw_tss guest_tss;
-       struct desc_struct guest_idt[IDT_ENTRIES];
-       struct desc_struct guest_gdt[GDT_ENTRIES];
-};
-
 /* We have two pages shared with guests, per cpu.  */
 struct lguest_pages
 {
@@ -180,11 +134,7 @@ struct lguest
        /* Dead? */
        const char *dead;
 
-       /* The GDT entries copied into lguest_ro_state when running. */
-       struct desc_struct gdt[GDT_ENTRIES];
-
-       /* The IDT entries: some copied into lguest_ro_state when running. */
-       struct desc_struct idt[IDT_ENTRIES];
+       struct lguest_arch arch;
 
        /* Virtual clock device */
        struct hrtimer hrt;
@@ -239,6 +189,15 @@ void map_switcher_in_guest(struct lguest *lg, struct 
lguest_pages *pages);
 int demand_page(struct lguest *info, unsigned long cr2, int errcode);
 void pin_page(struct lguest *lg, unsigned long vaddr);
 
+/* <arch>/core.c: */
+void lguest_arch_host_init(void);
+void lguest_arch_host_fini(void);
+void lguest_arch_run_guest(struct lguest *lg);
+void lguest_arch_handle_trap(struct lguest *lg);
+
+/* <arch>/switcher.S: */
+extern char start_switcher_text[], end_switcher_text[], switch_to_guest[];
+
 /* lguest_user.c: */
 int lguest_device_init(void);
 void lguest_device_remove(void);
diff --git a/drivers/lguest/segments.c b/drivers/lguest/segments.c
index 9b81119..95eb9cf 100644
--- a/drivers/lguest/segments.c
+++ b/drivers/lguest/segments.c
@@ -73,14 +73,14 @@ static void fixup_gdt_table(struct lguest *lg, unsigned 
start, unsigned end)
                /* Segment descriptors contain a privilege level: the Guest is
                 * sometimes careless and leaves this as 0, even though it's
                 * running at privilege level 1.  If so, we fix it here. */
-               if ((lg->gdt[i].b & 0x00006000) == 0)
-                       lg->gdt[i].b |= (GUEST_PL << 13);
+               if ((lg->arch.gdt[i].b & 0x00006000) == 0)
+                       lg->arch.gdt[i].b |= (GUEST_PL << 13);
 
                /* Each descriptor has an "accessed" bit.  If we don't set it
                 * now, the CPU will try to set it when the Guest first loads
                 * that entry into a segment register.  But the GDT isn't
                 * writable by the Guest, so bad things can happen. */
-               lg->gdt[i].b |= 0x00000100;
+               lg->arch.gdt[i].b |= 0x00000100;
        }
 }
 
@@ -106,12 +106,12 @@ void setup_default_gdt_entries(struct lguest_ro_state 
*state)
 void setup_guest_gdt(struct lguest *lg)
 {
        /* Start with full 0-4G segments... */
-       lg->gdt[GDT_ENTRY_KERNEL_CS] = FULL_EXEC_SEGMENT;
-       lg->gdt[GDT_ENTRY_KERNEL_DS] = FULL_SEGMENT;
+       lg->arch.gdt[GDT_ENTRY_KERNEL_CS] = FULL_EXEC_SEGMENT;
+       lg->arch.gdt[GDT_ENTRY_KERNEL_DS] = FULL_SEGMENT;
        /* ...except the Guest is allowed to use them, so set the privilege
         * level appropriately in the flags. */
-       lg->gdt[GDT_ENTRY_KERNEL_CS].b |= (GUEST_PL << 13);
-       lg->gdt[GDT_ENTRY_KERNEL_DS].b |= (GUEST_PL << 13);
+       lg->arch.gdt[GDT_ENTRY_KERNEL_CS].b |= (GUEST_PL << 13);
+       lg->arch.gdt[GDT_ENTRY_KERNEL_DS].b |= (GUEST_PL << 13);
 }
 
 /* Like the IDT, we never simply use the GDT the Guest gives us.  We set up the
@@ -126,7 +126,7 @@ void copy_gdt_tls(const struct lguest *lg, struct 
desc_struct *gdt)
        unsigned int i;
 
        for (i = GDT_ENTRY_TLS_MIN; i <= GDT_ENTRY_TLS_MAX; i++)
-               gdt[i] = lg->gdt[i];
+               gdt[i] = lg->arch.gdt[i];
 }
 
 /* This is the full version */
@@ -138,7 +138,7 @@ void copy_gdt(const struct lguest *lg, struct desc_struct 
*gdt)
         * replaced.  See ignored_gdt() above. */
        for (i = 0; i < GDT_ENTRIES; i++)
                if (!ignored_gdt(i))
-                       gdt[i] = lg->gdt[i];
+                       gdt[i] = lg->arch.gdt[i];
 }
 
 /* This is where the Guest asks us to load a new GDT (LHCALL_LOAD_GDT). */
@@ -146,12 +146,12 @@ void load_guest_gdt(struct lguest *lg, unsigned long 
table, u32 num)
 {
        /* We assume the Guest has the same number of GDT entries as the
         * Host, otherwise we'd have to dynamically allocate the Guest GDT. */
-       if (num > ARRAY_SIZE(lg->gdt))
+       if (num > ARRAY_SIZE(lg->arch.gdt))
                kill_guest(lg, "too many gdt entries %i", num);
 
        /* We read the whole thing in, then fix it up. */
-       lgread(lg, lg->gdt, table, num * sizeof(lg->gdt[0]));
-       fixup_gdt_table(lg, 0, ARRAY_SIZE(lg->gdt));
+       lgread(lg, lg->arch.gdt, table, num * sizeof(lg->arch.gdt[0]));
+       fixup_gdt_table(lg, 0, ARRAY_SIZE(lg->arch.gdt));
        /* Mark that the GDT changed so the core knows it has to copy it again,
         * even if the Guest is run on the same CPU. */
        lg->changed |= CHANGED_GDT;
@@ -159,7 +159,7 @@ void load_guest_gdt(struct lguest *lg, unsigned long table, 
u32 num)
 
 void guest_load_tls(struct lguest *lg, unsigned long gtls)
 {
-       struct desc_struct *tls = &lg->gdt[GDT_ENTRY_TLS_MIN];
+       struct desc_struct *tls = &lg->arch.gdt[GDT_ENTRY_TLS_MIN];
 
        lgread(lg, tls, gtls, sizeof(*tls)*GDT_ENTRY_TLS_ENTRIES);
        fixup_gdt_table(lg, GDT_ENTRY_TLS_MIN, GDT_ENTRY_TLS_MAX+1);
diff --git a/drivers/lguest/x86/core.c b/drivers/lguest/x86/core.c
new file mode 100644
index 0000000..e2f46b1
--- /dev/null
+++ b/drivers/lguest/x86/core.c
@@ -0,0 +1,476 @@
+/*
+ * Copyright (C) 2006, Rusty Russell <[EMAIL PROTECTED]> IBM Corporation.
+ * Copyright (C) 2007, Jes Sorensen <[EMAIL PROTECTED]> SGI.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
+ * NON INFRINGEMENT.  See the GNU General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+#include <linux/kernel.h>
+#include <linux/start_kernel.h>
+#include <linux/string.h>
+#include <linux/console.h>
+#include <linux/screen_info.h>
+#include <linux/irq.h>
+#include <linux/interrupt.h>
+#include <linux/clocksource.h>
+#include <linux/clockchips.h>
+#include <linux/cpu.h>
+#include <linux/lguest.h>
+#include <linux/lguest_launcher.h>
+#include <linux/lguest_bus.h>
+#include <asm/paravirt.h>
+#include <asm/param.h>
+#include <asm/page.h>
+#include <asm/pgtable.h>
+#include <asm/desc.h>
+#include <asm/setup.h>
+#include <asm/lguest.h>
+#include <asm/uaccess.h>
+#include <asm/i387.h>
+#include "../lg.h"
+
+static int cpu_had_pge;
+
+static struct {
+       unsigned long offset;
+       unsigned short segment;
+} lguest_entry;
+
+/* Offset from where switcher.S was compiled to where we've copied it */
+static unsigned long switcher_offset(void)
+{
+       return SWITCHER_ADDR - (unsigned long)start_switcher_text;
+}
+
+/* This cpu's struct lguest_pages. */
+static struct lguest_pages *lguest_pages(unsigned int cpu)
+{
+       return &(((struct lguest_pages *)
+                 (SWITCHER_ADDR + SHARED_SWITCHER_PAGES*PAGE_SIZE))[cpu]);
+}
+
+static DEFINE_PER_CPU(struct lguest *, last_guest);
+
+/*S:010
+ * We are getting close to the Switcher.
+ *
+ * Remember that each CPU has two pages which are visible to the Guest when it
+ * runs on that CPU.  This has to contain the state for that Guest: we copy the
+ * state in just before we run the Guest.
+ *
+ * Each Guest has "changed" flags which indicate what has changed in the Guest
+ * since it last ran.  We saw this set in interrupts_and_traps.c and
+ * segments.c.
+ */
+static void copy_in_guest_info(struct lguest *lg, struct lguest_pages *pages)
+{
+       /* Copying all this data can be quite expensive.  We usually run the
+        * same Guest we ran last time (and that Guest hasn't run anywhere else
+        * meanwhile).  If that's not the case, we pretend everything in the
+        * Guest has changed. */
+       if (__get_cpu_var(last_guest) != lg || lg->last_pages != pages) {
+               __get_cpu_var(last_guest) = lg;
+               lg->last_pages = pages;
+               lg->changed = CHANGED_ALL;
+       }
+
+       /* These copies are pretty cheap, so we do them unconditionally: */
+       /* Save the current Host top-level page directory. */
+       pages->state.host_cr3 = __pa(current->mm->pgd);
+       /* Set up the Guest's page tables to see this CPU's pages (and no
+        * other CPU's pages). */
+       map_switcher_in_guest(lg, pages);
+       /* Set up the two "TSS" members which tell the CPU what stack to use
+        * for traps which do directly into the Guest (ie. traps at privilege
+        * level 1). */
+       pages->state.guest_tss.esp1 = lg->esp1;
+       pages->state.guest_tss.ss1 = lg->ss1;
+
+       /* Copy direct-to-Guest trap entries. */
+       if (lg->changed & CHANGED_IDT)
+               copy_traps(lg, pages->state.guest_idt, default_idt_entries);
+
+       /* Copy all GDT entries which the Guest can change. */
+       if (lg->changed & CHANGED_GDT)
+               copy_gdt(lg, pages->state.guest_gdt);
+       /* If only the TLS entries have changed, copy them. */
+       else if (lg->changed & CHANGED_GDT_TLS)
+               copy_gdt_tls(lg, pages->state.guest_gdt);
+
+       /* Mark the Guest as unchanged for next time. */
+       lg->changed = 0;
+}
+
+/* Finally: the code to actually call into the Switcher to run the Guest. */
+static void run_guest_once(struct lguest *lg, struct lguest_pages *pages)
+{
+       /* This is a dummy value we need for GCC's sake. */
+       unsigned int clobber;
+
+       /* Copy the guest-specific information into this CPU's "struct
+        * lguest_pages". */
+       copy_in_guest_info(lg, pages);
+
+       /* Set the trap number to 256 (impossible value).  If we fault while
+        * switching to the Guest (bad segment registers or bug), this will
+        * cause us to abort the Guest. */
+       lg->regs->trapnum = 256;
+
+       /* Now: we push the "eflags" register on the stack, then do an "lcall".
+        * This is how we change from using the kernel code segment to using
+        * the dedicated lguest code segment, as well as jumping into the
+        * Switcher.
+        *
+        * The lcall also pushes the old code segment (KERNEL_CS) onto the
+        * stack, then the address of this call.  This stack layout happens to
+        * exactly match the stack of an interrupt... */
+       asm volatile("pushf; lcall *lguest_entry"
+                    /* This is how we tell GCC that %eax ("a") and %ebx ("b")
+                     * are changed by this routine.  The "=" means output. */
+                    : "=a"(clobber), "=b"(clobber)
+                    /* %eax contains the pages pointer.  ("0" refers to the
+                     * 0-th argument above, ie "a").  %ebx contains the
+                     * physical address of the Guest's top-level page
+                     * directory. */
+                    : "0"(pages), "1"(__pa(lg->pgdirs[lg->pgdidx].pgdir))
+                    /* We tell gcc that all these registers could change,
+                     * which means we don't have to save and restore them in
+                     * the Switcher. */
+                    : "memory", "%edx", "%ecx", "%edi", "%esi");
+}
+/*:*/
+
+/*H:040 This is the i386-specific code to setup and run the Guest.  Interrupts
+ * are disabled: we own the CPU. */
+void lguest_arch_run_guest(struct lguest *lg)
+{
+       /* Remember the awfully-named TS bit?  If the Guest has asked
+        * to set it we set it now, so we can trap and pass that trap
+        * to the Guest if it uses the FPU. */
+       if (lg->ts)
+               lguest_set_ts();
+
+       /* SYSENTER is an optimized way of doing system calls.  We
+        * can't allow it because it always jumps to privilege level 0.
+        * A normal Guest won't try it because we don't advertise it in
+        * CPUID, but a malicious Guest (or malicious Guest userspace
+        * program) could, so we tell the CPU to disable it before
+        * running the Guest. */
+       if (boot_cpu_has(X86_FEATURE_SEP))
+               wrmsr(MSR_IA32_SYSENTER_CS, 0, 0);
+
+       /* Now we actually run the Guest.  It will pop back out when
+        * something interesting happens, and we can examine its
+        * registers to see what it was doing. */
+       run_guest_once(lg, lguest_pages(raw_smp_processor_id()));
+
+       /* The "regs" pointer contains two extra entries which are not
+        * really registers: a trap number which says what interrupt or
+        * trap made the switcher code come back, and an error code
+        * which some traps set.  */
+
+       /* If the Guest page faulted, then the cr2 register will tell
+        * us the bad virtual address.  We have to grab this now,
+        * because once we re-enable interrupts an interrupt could
+        * fault and thus overwrite cr2, or we could even move off to a
+        * different CPU. */
+       if (lg->regs->trapnum == 14)
+               lg->arch.last_pagefault = read_cr2();
+       /* Similarly, if we took a trap because the Guest used the FPU,
+        * we have to restore the FPU it expects to see. */
+       else if (lg->regs->trapnum == 7)
+               math_state_restore();
+
+       /* Restore SYSENTER if it's supposed to be on. */
+       if (boot_cpu_has(X86_FEATURE_SEP))
+               wrmsr(MSR_IA32_SYSENTER_CS, __KERNEL_CS, 0);
+}
+
+/*H:130 Our Guest is usually so well behaved; it never tries to do things it
+ * isn't allowed to.  Unfortunately, Linux's paravirtual infrastructure isn't
+ * quite complete, because it doesn't contain replacements for the Intel I/O
+ * instructions.  As a result, the Guest sometimes fumbles across one during
+ * the boot process as it probes for various things which are usually attached
+ * to a PC.
+ *
+ * When the Guest uses one of these instructions, we get trap #13 (General
+ * Protection Fault) and come here.  We see if it's one of those troublesome
+ * instructions and skip over it.  We return true if we did. */
+static int emulate_insn(struct lguest *lg)
+{
+       u8 insn;
+       unsigned int insnlen = 0, in = 0, shift = 0;
+       /* The eip contains the *virtual* address of the Guest's instruction:
+        * guest_pa just subtracts the Guest's page_offset. */
+       unsigned long physaddr = guest_pa(lg, lg->regs->eip);
+
+       /* The guest_pa() function only works for Guest kernel addresses, but
+        * that's all we're trying to do anyway. */
+       if (lg->regs->eip < lg->page_offset)
+               return 0;
+
+       /* Decoding x86 instructions is icky. */
+       lgread(lg, &insn, physaddr, 1);
+
+       /* 0x66 is an "operand prefix".  It means it's using the upper 16 bits
+          of the eax register. */
+       if (insn == 0x66) {
+               shift = 16;
+               /* The instruction is 1 byte so far, read the next byte. */
+               insnlen = 1;
+               lgread(lg, &insn, physaddr + insnlen, 1);
+       }
+
+       /* We can ignore the lower bit for the moment and decode the 4 opcodes
+        * we need to emulate. */
+       switch (insn & 0xFE) {
+       case 0xE4: /* in     <next byte>,%al */
+               insnlen += 2;
+               in = 1;
+               break;
+       case 0xEC: /* in     (%dx),%al */
+               insnlen += 1;
+               in = 1;
+               break;
+       case 0xE6: /* out    %al,<next byte> */
+               insnlen += 2;
+               break;
+       case 0xEE: /* out    %al,(%dx) */
+               insnlen += 1;
+               break;
+       default:
+               /* OK, we don't know what this is, can't emulate. */
+               return 0;
+       }
+
+       /* If it was an "IN" instruction, they expect the result to be read
+        * into %eax, so we change %eax.  We always return all-ones, which
+        * traditionally means "there's nothing there". */
+       if (in) {
+               /* Lower bit tells is whether it's a 16 or 32 bit access */
+               if (insn & 0x1)
+                       lg->regs->eax = 0xFFFFFFFF;
+               else
+                       lg->regs->eax |= (0xFFFF << shift);
+       }
+       /* Finally, we've "done" the instruction, so move past it. */
+       lg->regs->eip += insnlen;
+       /* Success! */
+       return 1;
+}
+
+/*H:050 Once we've re-enabled interrupts, we look at why the Guest exited. */
+void lguest_arch_handle_trap(struct lguest *lg)
+{
+       switch (lg->regs->trapnum) {
+       case 13: /* We've intercepted a GPF. */
+                /* Check if this was one of those annoying IN or OUT
+                 * instructions which we need to emulate.  If so, we
+                 * just go back into the Guest after we've done it. */
+               if (lg->regs->errcode == 0) {
+                       if (emulate_insn(lg))
+                               return;
+               }
+               break;
+       case 14: /* We've intercepted a page fault. */
+                /* The Guest accessed a virtual address that wasn't
+                 * mapped.  This happens a lot: we don't actually set
+                 * up most of the page tables for the Guest at all when
+                 * we start: as it runs it asks for more and more, and
+                 * we set them up as required. In this case, we don't
+                 * even tell the Guest that the fault happened.
+                 *
+                 * The errcode tells whether this was a read or a
+                 * write, and whether kernel or userspace code. */
+               if (demand_page(lg, lg->arch.last_pagefault, lg->regs->errcode))
+                       return;
+
+                /* OK, it's really not there (or not OK): the Guest
+                 * needs to know.  We write out the cr2 value so it
+                 * knows where the fault occurred.
+                 *
+                 * Note that if the Guest were really messed up, this
+                 * could happen before it's done the INITIALIZE
+                 * hypercall, so lg->lguest_data will be NULL */
+               if (lg->lguest_data &&
+                   put_user(lg->arch.last_pagefault, &lg->lguest_data->cr2))
+                       kill_guest(lg, "Writing cr2");
+               break;
+       case 7: /* We've intercepted a Device Not Available fault. */
+               /* If the Guest doesn't want to know, we already
+                * restored the Floating Point Unit, so we just
+                * continue without telling it. */
+               if (!lg->ts)
+                       return;
+               break;
+       case 32 ... 255:
+               /* These values mean a real interrupt occurred, in
+                * which case the Host handler has already been run.
+                * We just do a friendly check if another process
+                * should now be run, then fall through to loop
+                * around: */
+               cond_resched();
+       case LGUEST_TRAP_ENTRY: /* Handled before re-entering Guest */
+               return;
+       }
+
+       /* We didn't handle the trap, so it needs to go to the Guest. */
+       if (!deliver_trap(lg, lg->regs->trapnum))
+               /* If the Guest doesn't have a handler (either it hasn't
+                * registered any yet, or it's one of the faults we don't let
+                * it handle), it dies with a cryptic error message. */
+               kill_guest(lg, "unhandled trap %li at %#lx (%#lx)",
+                          lg->regs->trapnum, lg->regs->eip,
+                          lg->regs->trapnum == 14 ? lg->arch.last_pagefault
+                          : lg->regs->errcode);
+}
+
+/* Now we can look at each of the routines this calls, in increasing order of
+ * complexity: do_hypercalls(), emulate_insn(), maybe_do_interrupt(),
+ * deliver_trap() and demand_page().  After all those, we'll be ready to
+ * examine the Switcher, and our philosophical understanding of the Host/Guest
+ * duality will be complete. :*/
+static void adjust_pge(void *on)
+{
+       if (on)
+               write_cr4(read_cr4() | X86_CR4_PGE);
+       else
+               write_cr4(read_cr4() & ~X86_CR4_PGE);
+}
+
+/*H:020 Now the Switcher is mapped and every thing else is ready, we need to do
+ * some more i386-specific initialization. */
+void __init lguest_arch_host_init(void)
+{
+       int i;
+
+       /* Most of the i386/switcher.S doesn't care that it's been moved; on
+        * Intel, jumps are relative, and it doesn't access any references to
+        * external code or data.
+        *
+        * The only exception is the interrupt handlers in switcher.S: their
+        * addresses are placed in a table (default_idt_entries), so we need to
+        * update the table with the new addresses.  switcher_offset() is a
+        * convenience function which returns the distance between the builtin
+        * switcher code and the high-mapped copy we just made. */
+       for (i = 0; i < IDT_ENTRIES; i++)
+               default_idt_entries[i] += switcher_offset();
+
+       /*
+        * Set up the Switcher's per-cpu areas.
+        *
+        * Each CPU gets two pages of its own within the high-mapped region
+        * (aka. "struct lguest_pages").  Much of this can be initialized now,
+        * but some depends on what Guest we are running (which is set up in
+        * copy_in_guest_info()).
+        */
+       for_each_possible_cpu(i) {
+               /* lguest_pages() returns this CPU's two pages. */
+               struct lguest_pages *pages = lguest_pages(i);
+               /* This is a convenience pointer to make the code fit one
+                * statement to a line. */
+               struct lguest_ro_state *state = &pages->state;
+
+               /* The Global Descriptor Table: the Host has a different one
+                * for each CPU.  We keep a descriptor for the GDT which says
+                * where it is and how big it is (the size is actually the last
+                * byte, not the size, hence the "-1"). */
+               state->host_gdt_desc.size = GDT_SIZE-1;
+               state->host_gdt_desc.address = (long)get_cpu_gdt_table(i);
+
+               /* All CPUs on the Host use the same Interrupt Descriptor
+                * Table, so we just use store_idt(), which gets this CPU's IDT
+                * descriptor. */
+               store_idt(&state->host_idt_desc);
+
+               /* The descriptors for the Guest's GDT and IDT can be filled
+                * out now, too.  We copy the GDT & IDT into ->guest_gdt and
+                * ->guest_idt before actually running the Guest. */
+               state->guest_idt_desc.size = sizeof(state->guest_idt)-1;
+               state->guest_idt_desc.address = (long)&state->guest_idt;
+               state->guest_gdt_desc.size = sizeof(state->guest_gdt)-1;
+               state->guest_gdt_desc.address = (long)&state->guest_gdt;
+
+               /* We know where we want the stack to be when the Guest enters
+                * the switcher: in pages->regs.  The stack grows upwards, so
+                * we start it at the end of that structure. */
+               state->guest_tss.esp0 = (long)(&pages->regs + 1);
+               /* And this is the GDT entry to use for the stack: we keep a
+                * couple of special LGUEST entries. */
+               state->guest_tss.ss0 = LGUEST_DS;
+
+               /* x86 can have a finegrained bitmap which indicates what I/O
+                * ports the process can use.  We set it to the end of our
+                * structure, meaning "none". */
+               state->guest_tss.io_bitmap_base = sizeof(state->guest_tss);
+
+               /* Some GDT entries are the same across all Guests, so we can
+                * set them up now. */
+               setup_default_gdt_entries(state);
+               /* Most IDT entries are the same for all Guests, too.*/
+               setup_default_idt_entries(state, default_idt_entries);
+
+               /* The Host needs to be able to use the LGUEST segments on this
+                * CPU, too, so put them in the Host GDT. */
+               get_cpu_gdt_table(i)[GDT_ENTRY_LGUEST_CS] = FULL_EXEC_SEGMENT;
+               get_cpu_gdt_table(i)[GDT_ENTRY_LGUEST_DS] = FULL_SEGMENT;
+       }
+
+       /* In the Switcher, we want the %cs segment register to use the
+        * LGUEST_CS GDT entry: we've put that in the Host and Guest GDTs, so
+        * it will be undisturbed when we switch.  To change %cs and jump we
+        * need this structure to feed to Intel's "lcall" instruction. */
+       lguest_entry.offset = (long)switch_to_guest + switcher_offset();
+       lguest_entry.segment = LGUEST_CS;
+
+       /* Finally, we need to turn off "Page Global Enable".  PGE is an
+        * optimization where page table entries are specially marked to show
+        * they never change.  The Host kernel marks all the kernel pages this
+        * way because it's always present, even when userspace is running.
+        *
+        * Lguest breaks this: unbeknownst to the rest of the Host kernel, we
+        * switch to the Guest kernel.  If you don't disable this on all CPUs,
+        * you'll get really weird bugs that you'll chase for two days.
+        *
+        * I used to turn PGE off every time we switched to the Guest and back
+        * on when we return, but that slowed the Switcher down noticibly. */
+
+       /* We don't need the complexity of CPUs coming and going while we're
+        * doing this. */
+       lock_cpu_hotplug();
+       if (cpu_has_pge) { /* We have a broader idea of "global". */
+               /* Remember that this was originally set (for cleanup). */
+               cpu_had_pge = 1;
+               /* adjust_pge is a helper function which sets or unsets the PGE
+                * bit on its CPU, depending on the argument (0 == unset). */
+               on_each_cpu(adjust_pge, (void *)0, 0, 1);
+               /* Turn off the feature in the global feature set. */
+               clear_bit(X86_FEATURE_PGE, boot_cpu_data.x86_capability);
+       }
+       unlock_cpu_hotplug();
+};
+/*:*/
+
+void __exit lguest_arch_host_fini(void)
+{
+       /* If we had PGE before we started, turn it back on now. */
+       lock_cpu_hotplug();
+       if (cpu_had_pge) {
+               set_bit(X86_FEATURE_PGE, boot_cpu_data.x86_capability);
+               /* adjust_pge's argument "1" means set PGE. */
+               on_each_cpu(adjust_pge, (void *)1, 0, 1);
+       }
+       unlock_cpu_hotplug();
+}
diff --git a/drivers/lguest/x86/switcher_32.S b/drivers/lguest/x86/switcher_32.S
index a3d23f7..e66cec5 100644
--- a/drivers/lguest/x86/switcher_32.S
+++ b/drivers/lguest/x86/switcher_32.S
@@ -48,7 +48,8 @@
 #include <linux/linkage.h>
 #include <asm/asm-offsets.h>
 #include <asm/page.h>
-#include "../lg.h"
+#include <asm/segment.h>
+#include <asm/lguest.h>
 
 // We mark the start of the code to copy
 // It's placed in .text tho it's never run here
diff --git a/include/asm-x86/lguest.h b/include/asm-x86/lguest.h
new file mode 100644
index 0000000..f10f1c6
--- /dev/null
+++ b/include/asm-x86/lguest.h
@@ -0,0 +1,87 @@
+#ifndef _X86_LGUEST_H
+#define _X86_LGUEST_H
+
+#define GDT_ENTRY_LGUEST_CS    10
+#define GDT_ENTRY_LGUEST_DS    11
+#define LGUEST_CS              (GDT_ENTRY_LGUEST_CS * 8)
+#define LGUEST_DS              (GDT_ENTRY_LGUEST_DS * 8)
+
+#ifndef __ASSEMBLY__
+#include <asm/desc.h>
+
+#define GUEST_PL 1
+
+/* Every guest maps the core switcher code. */
+#define SHARED_SWITCHER_PAGES \
+       DIV_ROUND_UP(end_switcher_text - start_switcher_text, PAGE_SIZE)
+/* Pages for switcher itself, then two pages per cpu */
+#define TOTAL_SWITCHER_PAGES (SHARED_SWITCHER_PAGES + 2 * NR_CPUS)
+
+/* We map at -4M for ease of mapping into the guest (one PTE page). */
+#define SWITCHER_ADDR 0xFFC00000
+
+/* Found in switcher.S */
+extern unsigned long default_idt_entries[];
+
+struct lguest_regs
+{
+       /* Manually saved part. */
+       unsigned long ebx, ecx, edx;
+       unsigned long esi, edi, ebp;
+       unsigned long gs;
+       unsigned long eax;
+       unsigned long fs, ds, es;
+       unsigned long trapnum, errcode;
+       /* Trap pushed part */
+       unsigned long eip;
+       unsigned long cs;
+       unsigned long eflags;
+       unsigned long esp;
+       unsigned long ss;
+};
+
+/* This is a guest-specific page (mapped ro) into the guest. */
+struct lguest_ro_state
+{
+       /* Host information we need to restore when we switch back. */
+       u32 host_cr3;
+       struct Xgt_desc_struct host_idt_desc;
+       struct Xgt_desc_struct host_gdt_desc;
+       u32 host_sp;
+
+       /* Fields which are used when guest is running. */
+       struct Xgt_desc_struct guest_idt_desc;
+       struct Xgt_desc_struct guest_gdt_desc;
+       struct i386_hw_tss guest_tss;
+       struct desc_struct guest_idt[IDT_ENTRIES];
+       struct desc_struct guest_gdt[GDT_ENTRIES];
+};
+
+struct lguest_arch
+{
+       /* The GDT entries copied into lguest_ro_state when running. */
+       struct desc_struct gdt[GDT_ENTRIES];
+
+       /* The IDT entries: some copied into lguest_ro_state when running. */
+       struct desc_struct idt[IDT_ENTRIES];
+
+       /* The address of the last guest-visible pagefault (ie. cr2). */
+       unsigned long last_pagefault;
+};
+
+static inline void lguest_set_ts(void)
+{
+       u32 cr0;
+
+       cr0 = read_cr0();
+       if (!(cr0 & 8))
+               write_cr0(cr0|8);
+}
+
+/* Full 4G segment descriptors, suitable for CS and DS. */
+#define FULL_EXEC_SEGMENT ((struct desc_struct){0x0000ffff, 0x00cf9b00})
+#define FULL_SEGMENT ((struct desc_struct){0x0000ffff, 0x00cf9300})
+
+#endif /* __ASSEMBLY__ */
+
+#endif
-
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