repository: /home/avi/kvm/linux-2.6
branch: pf-emul-opt
commit a933cbbe7973d6f8ebb8a2728b73f15b1f107f41
Author: Avi Kivity <[EMAIL PROTECTED]>
Date: Wed Nov 28 12:34:13 2007 +0200
KVM: MMU: Return type of page fault from page fault handler
We distinguish between the three types of page faults:
- ordinary shadow faults; we can return to the guest
- mmio; emulate or die
- page table write; emulate or unshadow
While the code already handles all three paths correctly, this makes it more
explicit.
Signed-off-by: Avi Kivity <[EMAIL PROTECTED]>
diff --git a/drivers/kvm/kvm.h b/drivers/kvm/kvm.h
index be18620..07e8dbc 100644
--- a/drivers/kvm/kvm.h
+++ b/drivers/kvm/kvm.h
@@ -114,6 +114,11 @@ struct kvm_mmu_page {
struct kvm_vcpu;
extern struct kmem_cache *kvm_vcpu_cache;
+/* Return codes for kvm_mmu.page_fault() */
+#define PF_HANDLED 0 /* No further action needed */
+#define PF_MMIO 1 /* Emulate */
+#define PF_PTWRITE 2 /* Emulate or unshadow */
+
/*
* x86 supports 3 paging modes (4-level 64-bit, 3-level 64-bit, and 2-level
* 32-bit). The kvm_mmu structure abstracts the details of the current mmu
diff --git a/drivers/kvm/mmu.c b/drivers/kvm/mmu.c
index 9b9d1b6..552d7e6 100644
--- a/drivers/kvm/mmu.c
+++ b/drivers/kvm/mmu.c
@@ -897,7 +897,7 @@ static int nonpaging_map(struct kvm_vcpu *vcpu, gva_t v,
struct page *page)
was_rmapped = is_rmap_pte(pte);
if (is_shadow_present_pte(pte) && is_writeble_pte(pte))
{
kvm_release_page_clean(page);
- return 0;
+ return PF_HANDLED;
}
mark_page_dirty(vcpu->kvm, v >> PAGE_SHIFT);
page_header_update_slot(vcpu->kvm, table,
@@ -910,7 +910,7 @@ static int nonpaging_map(struct kvm_vcpu *vcpu, gva_t v,
struct page *page)
else
kvm_release_page_clean(page);
- return 0;
+ return PF_HANDLED;
}
if (table[index] == shadow_trap_nonpresent_pte) {
@@ -1039,7 +1039,7 @@ static int nonpaging_page_fault(struct kvm_vcpu *vcpu,
gva_t gva,
if (is_error_page(page)) {
kvm_release_page_clean(page);
- return 1;
+ return PF_MMIO;
}
return nonpaging_map(vcpu, gva & PAGE_MASK, page);
@@ -1367,15 +1367,17 @@ void __kvm_mmu_free_some_pages(struct kvm_vcpu *vcpu)
int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gva_t cr2, u32 error_code)
{
- int r;
+ int r, pfr;
enum emulation_result er;
mutex_lock(&vcpu->kvm->lock);
- r = vcpu->mmu.page_fault(vcpu, cr2, error_code);
- if (r < 0)
+ pfr = vcpu->mmu.page_fault(vcpu, cr2, error_code);
+ if (pfr < 0) {
+ r = pfr;
goto out;
+ }
- if (!r) {
+ if (pfr == PF_HANDLED) {
r = 1;
goto out;
}
@@ -1394,8 +1396,14 @@ int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gva_t cr2,
u32 error_code)
++vcpu->stat.mmio_exits;
return 0;
case EMULATE_FAIL:
- kvm_report_emulation_failure(vcpu, "pagetable");
- return 1;
+ if (pfr == PF_PTWRITE) {
+ kvm_report_emulation_failure(vcpu, "pagetable");
+ kvm_mmu_unprotect_page_virt(vcpu, cr2);
+ return 1;
+ } else { /* PF_MMIO */
+ kvm_report_emulation_failure(vcpu, "mmio");
+ return -EOPNOTSUPP;
+ }
default:
BUG();
}
diff --git a/drivers/kvm/paging_tmpl.h b/drivers/kvm/paging_tmpl.h
index b24bc7c..aa9f2c5 100644
--- a/drivers/kvm/paging_tmpl.h
+++ b/drivers/kvm/paging_tmpl.h
@@ -410,7 +410,7 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t
addr,
pgprintk("%s: guest page fault\n", __FUNCTION__);
inject_page_fault(vcpu, addr, walker.error_code);
vcpu->last_pt_write_count = 0; /* reset fork detector */
- return 0;
+ return PF_HANDLED;
}
shadow_pte = FNAME(fetch)(vcpu, addr, &walker, user_fault, write_fault,
@@ -425,12 +425,12 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t
addr,
* mmio: emulate if accessible, otherwise its a guest fault.
*/
if (is_io_pte(*shadow_pte))
- return 1;
+ return PF_MMIO;
++vcpu->stat.pf_fixed;
kvm_mmu_audit(vcpu, "post page fault (fixed)");
- return write_pt;
+ return write_pt ? PF_PTWRITE : PF_HANDLED;
}
static gpa_t FNAME(gva_to_gpa)(struct kvm_vcpu *vcpu, gva_t vaddr)
diff --git a/drivers/kvm/x86.c b/drivers/kvm/x86.c
index c70ac33..495fa73 100644
--- a/drivers/kvm/x86.c
+++ b/drivers/kvm/x86.c
@@ -1713,8 +1713,6 @@ int emulate_instruction(struct kvm_vcpu *vcpu,
++vcpu->stat.insn_emulation;
if (r) {
++vcpu->stat.insn_emulation_fail;
- if (kvm_mmu_unprotect_page_virt(vcpu, cr2))
- return EMULATE_DONE;
return EMULATE_FAIL;
}
}
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