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

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Message-ID: <20240710174031.312055-5-pbonzini@redhat.com>
Date: Wed, 10 Jul 2024 13:40:28 -0400
From: Paolo Bonzini <pbonzini@...hat.com>
To: linux-kernel@...r.kernel.org,
	kvm@...r.kernel.org
Cc: isaku.yamahata@...el.com,
	seanjc@...gle.com,
	binbin.wu@...ux.intel.com,
	xiaoyao.li@...el.com
Subject: [PATCH v5 4/7] KVM: x86/mmu: Account pf_{fixed,emulate,spurious} in callers of "do page fault"

From: Sean Christopherson <seanjc@...gle.com>

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@...gle.com>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
 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