[PATCH v5 4/7] KVM: x86/mmu: Account pf_{fixed,emulate,spurious} in callers of "do page fault"

From: Paolo Bonzini
Date: Wed Jul 10 2024 - 13:41:42 EST


From: Sean Christopherson <seanjc@xxxxxxxxxx>

Move the accounting of the result of kvm_mmu_do_page_fault() to its
callers, as only pf_fixed is common to guest page faults and async #PFs,
and upcoming support KVM_PRE_FAULT_MEMORY won't bump _any_ stats.

Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
---
arch/x86/kvm/mmu/mmu.c | 19 ++++++++++++++++++-
arch/x86/kvm/mmu/mmu_internal.h | 13 -------------
2 files changed, 18 insertions(+), 14 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index aa437aacf55f..8c2c5c0afba1 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -4291,7 +4291,16 @@ void kvm_arch_async_page_ready(struct kvm_vcpu *vcpu, struct kvm_async_pf *work)
work->arch.cr3 != kvm_mmu_get_guest_pgd(vcpu, vcpu->arch.mmu))
return;

- kvm_mmu_do_page_fault(vcpu, work->cr2_or_gpa, work->arch.error_code, true, NULL);
+ r = kvm_mmu_do_page_fault(vcpu, work->cr2_or_gpa, work->arch.error_code,
+ true, NULL);
+
+ /*
+ * Account fixed page faults, otherwise they'll never be counted, but
+ * ignore stats for all other return times. Page-ready "faults" aren't
+ * truly spurious and never trigger emulation
+ */
+ if (r == RET_PF_FIXED)
+ vcpu->stat.pf_fixed++;
}

static inline u8 kvm_max_level_for_order(int order)
@@ -5935,6 +5944,14 @@ int noinline kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u64 err

if (r < 0)
return r;
+
+ if (r == RET_PF_FIXED)
+ vcpu->stat.pf_fixed++;
+ else if (r == RET_PF_EMULATE)
+ vcpu->stat.pf_emulate++;
+ else if (r == RET_PF_SPURIOUS)
+ vcpu->stat.pf_spurious++;
+
if (r != RET_PF_EMULATE)
return 1;

diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_internal.h
index 8efd31b3856b..444f55a5eed7 100644
--- a/arch/x86/kvm/mmu/mmu_internal.h
+++ b/arch/x86/kvm/mmu/mmu_internal.h
@@ -337,19 +337,6 @@ static inline int kvm_mmu_do_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
if (fault.write_fault_to_shadow_pgtable && emulation_type)
*emulation_type |= EMULTYPE_WRITE_PF_TO_SP;

- /*
- * Similar to above, prefetch faults aren't truly spurious, and the
- * async #PF path doesn't do emulation. Do count faults that are fixed
- * by the async #PF handler though, otherwise they'll never be counted.
- */
- if (r == RET_PF_FIXED)
- vcpu->stat.pf_fixed++;
- else if (prefetch)
- ;
- else if (r == RET_PF_EMULATE)
- vcpu->stat.pf_emulate++;
- else if (r == RET_PF_SPURIOUS)
- vcpu->stat.pf_spurious++;
return r;
}

--
2.43.0