repository: /home/avi/kvm/linux-2.6
branch: master
commit 2c9c2e9251adc775720df60d1522accf433d15d0
Author: Avi Kivity <[EMAIL PROTECTED]>
Date: Thu Nov 15 18:46:20 2007 +0200
KVM: VMX: Optimize vm entry by using %rsp as a GPR
Instead of storing the vcpu pointer on the stack, store it in rsp (as that
is the only GPR restored by vmx). This has two advantages:
- we no longer need to write HOST_RSP into the vmcs, as the vcpu pointer is
constant for a given guest
- finding the vcpu pointer (which is much more interesting than the stack)
is
simpler
This is safe since interrupts are disabled at this point.
Signed-off-by: Avi Kivity <[EMAIL PROTECTED]>
diff --git a/drivers/kvm/vmx.c b/drivers/kvm/vmx.c
index 7649986..90a019f 100644
--- a/drivers/kvm/vmx.c
+++ b/drivers/kvm/vmx.c
@@ -46,6 +46,7 @@ struct vmcs {
struct vcpu_vmx {
struct kvm_vcpu vcpu;
+ unsigned long host_rsp;
int launched;
u8 fail;
struct kvm_msr_entry *guest_msrs;
@@ -1497,6 +1498,13 @@ static int vmx_vcpu_setup(struct vcpu_vmx *vmx)
unsigned long kvm_vmx_return;
u32 exec_control;
+ /*
+ * We use rsp as a general purpose register pointing at the vcpu
+ * immediately after vmexit, as it's (a) more useful (b) doesn't
+ * change across invocations, saving us a vmwrite in the fast path.
+ */
+ vmcs_writel(HOST_RSP, (unsigned long)vmx);
+
/* I/O */
vmcs_write64(IO_BITMAP_A, page_to_phys(vmx_io_bitmap_a));
vmcs_write64(IO_BITMAP_B, page_to_phys(vmx_io_bitmap_b));
@@ -2188,6 +2196,7 @@ static int kvm_handle_exit(struct kvm_run *kvm_run,
struct kvm_vcpu *vcpu)
kvm_run->exit_reason = KVM_EXIT_FAIL_ENTRY;
kvm_run->fail_entry.hardware_entry_failure_reason
= vmcs_read32(VM_INSTRUCTION_ERROR);
+ vmx->fail = 0;
return 0;
}
@@ -2293,13 +2302,14 @@ static void vmx_vcpu_run(struct kvm_vcpu *vcpu, struct
kvm_run *kvm_run)
asm(
/* Store host registers */
#ifdef CONFIG_X86_64
- "push %%rdx; push %%rbp;"
- "push %%rcx \n\t"
+ "push %%rbp \n\t"
+ "mov %%rsp, %c[host_rsp](%0) \n\t"
+ "mov %0, %%rsp \n\t" /* in case vm entry fails */
#else
- "push %%edx; push %%ebp;"
- "push %%ecx \n\t"
+ "push %%ebp \n\t"
+ "mov %%esp, %c[host_rsp](%0) \n\t"
+ "mov %0, %%esp \n\t" /* in case vm entry fails */
#endif
- ASM_VMX_VMWRITE_RSP_RDX "\n\t"
/* Check if vmlaunch of vmresume is needed */
"cmpl $0, %c[launched](%0) \n\t"
/* Load guest registers. Don't clobber flags. */
@@ -2335,15 +2345,21 @@ static void vmx_vcpu_run(struct kvm_vcpu *vcpu, struct
kvm_run *kvm_run)
/* Enter guest mode */
"jne .Llaunched \n\t"
ASM_VMX_VMLAUNCH "\n\t"
- "jmp .Lkvm_vmx_return \n\t"
+ "jmp .Lkvm_vmx_fail \n\t"
".Llaunched: " ASM_VMX_VMRESUME "\n\t"
+ ".Lkvm_vmx_fail: \n\t"
+#ifdef CONFIG_X86_64
+ "movb $1, %c[fail](%%rsp) \n\t"
+#else
+ "movb $1, %c[fail](%%esp) \n\t"
+#endif
".Lkvm_vmx_return: "
/* Save guest registers, load host registers, keep flags */
#ifdef CONFIG_X86_64
- "xchg %0, (%%rsp) \n\t"
+ "xchg %0, %%rsp \n\t"
"mov %%rax, %c[rax](%0) \n\t"
"mov %%rbx, %c[rbx](%0) \n\t"
- "pushq (%%rsp); popq %c[rcx](%0) \n\t"
+ "mov %%rsp, %c[rcx](%0) \n\t"
"mov %%rdx, %c[rdx](%0) \n\t"
"mov %%rsi, %c[rsi](%0) \n\t"
"mov %%rdi, %c[rdi](%0) \n\t"
@@ -2359,12 +2375,13 @@ static void vmx_vcpu_run(struct kvm_vcpu *vcpu, struct
kvm_run *kvm_run)
"mov %%cr2, %%rax \n\t"
"mov %%rax, %c[cr2](%0) \n\t"
- "pop %%rbp; pop %%rbp; pop %%rdx \n\t"
+ "mov %c[host_rsp](%0), %%rsp \n\t"
+ "pop %%rbp \n\t"
#else
- "xchg %0, (%%esp) \n\t"
+ "xchg %0, %%esp \n\t"
"mov %%eax, %c[rax](%0) \n\t"
"mov %%ebx, %c[rbx](%0) \n\t"
- "pushl (%%esp); popl %c[rcx](%0) \n\t"
+ "mov %%esp, %c[rcx](%0) \n\t"
"mov %%edx, %c[rdx](%0) \n\t"
"mov %%esi, %c[rsi](%0) \n\t"
"mov %%edi, %c[rdi](%0) \n\t"
@@ -2372,12 +2389,13 @@ static void vmx_vcpu_run(struct kvm_vcpu *vcpu, struct
kvm_run *kvm_run)
"mov %%cr2, %%eax \n\t"
"mov %%eax, %c[cr2](%0) \n\t"
- "pop %%ebp; pop %%ebp; pop %%edx \n\t"
+ "mov %c[host_rsp](%0), %%esp \n\t"
+ "pop %%ebp \n\t"
#endif
- "setbe %c[fail](%0) \n\t"
- : : "c"(vmx), "d"((unsigned long)HOST_RSP),
+ : : "c"(vmx),
[launched]"i"(offsetof(struct vcpu_vmx, launched)),
[fail]"i"(offsetof(struct vcpu_vmx, fail)),
+ [host_rsp]"i"(offsetof(struct vcpu_vmx, host_rsp)),
[rax]"i"(offsetof(struct vcpu_vmx, vcpu.regs[VCPU_REGS_RAX])),
[rbx]"i"(offsetof(struct vcpu_vmx, vcpu.regs[VCPU_REGS_RBX])),
[rcx]"i"(offsetof(struct vcpu_vmx, vcpu.regs[VCPU_REGS_RCX])),
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