[3/7] KVM: x86/mmu: Extract __kvm_mmu_do_page_fault()

Commit Message

Paolo Bonzini April 17, 2024, 3:34 p.m. UTC

From: Isaku Yamahata <[e-mail]>

Extract out __kvm_mmu_do_page_fault() from kvm_mmu_do_page_fault().  The
inner function is to initialize struct kvm_page_fault and to call the fault
handler, and the outer function handles updating stats and converting
return code.  KVM_MAP_MEMORY will call the KVM page fault handler.

This patch makes the emulation_type always set irrelevant to the return
code.  kvm_mmu_page_fault() is the only caller of kvm_mmu_do_page_fault(),
and references the value only when PF_RET_EMULATE is returned.  Therefore,
this adjustment doesn't affect functionality.

No functional change intended.

Suggested-by: Sean Christopherson <[e-mail]>
Signed-off-by: Isaku Yamahata <[e-mail]>
Message-ID: <ddf1d9[e-mail]>
Signed-off-by: Paolo Bonzini <[e-mail]>
---
 arch/x86/kvm/mmu/mmu_internal.h | 38 +++++++++++++++++++++------------
 1 file changed, 24 insertions(+), 14 deletions(-)

Comments

Isaku Yamahata April 17, 2024, 7:47 p.m. UTC | #1

On Wed, Apr 17, 2024 at 11:34:46AM -0400,
Paolo Bonzini <[e-mail]> wrote:

> From: Isaku Yamahata <[e-mail]>
> 
> Extract out __kvm_mmu_do_page_fault() from kvm_mmu_do_page_fault().  The
> inner function is to initialize struct kvm_page_fault and to call the fault
> handler, and the outer function handles updating stats and converting
> return code.  KVM_MAP_MEMORY will call the KVM page fault handler.

To clarify to no update vcpu.stat, let me update the last sentence.
  
  KVM_MAP_MEMORY will call the KVM page fault handler without vcpu stat that
  doesn't make sense for pre-population because pre-population (outside TDX) has
  the purpose of avoiding page faults


> This patch makes the emulation_type always set irrelevant to the return
> code.  kvm_mmu_page_fault() is the only caller of kvm_mmu_do_page_fault(),
> and references the value only when PF_RET_EMULATE is returned.  Therefore,
> this adjustment doesn't affect functionality.

For the technical correctness, let me mention about NULL emulation_type.
I added "," and "with non-NULL emulation_type" to the second sentence.
  https://lore.kernel.org/all/[e-mail]/

  This patch makes the emulation_type always set, irrelevant to the return
  code. kvm_mmu_page_fault() is the only caller of kvm_mmu_do_page_fault() with
  non-NULL emulation_type and references the value only when PF_RET_EMULATE is
  returned. Therefore, this adjustment doesn't affect functionality.

Patch

diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_internal.h
index e68a60974cf4..9baae6c223ee 100644
--- a/arch/x86/kvm/mmu/mmu_internal.h
+++ b/arch/x86/kvm/mmu/mmu_internal.h
@@ -287,8 +287,8 @@  static inline void kvm_mmu_prepare_memory_fault_exit(struct kvm_vcpu *vcpu,
 				      fault->is_private);
 }
 
-static inline int kvm_mmu_do_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
-					u64 err, bool prefetch, int *emulation_type)
+static inline int __kvm_mmu_do_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
+					  u64 err, bool prefetch, int *emulation_type)
 {
 	struct kvm_page_fault fault = {
 		.addr = cr2_or_gpa,
@@ -318,6 +318,27 @@  static inline int kvm_mmu_do_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
 		fault.slot = kvm_vcpu_gfn_to_memslot(vcpu, fault.gfn);
 	}
 
+	if (IS_ENABLED(CONFIG_MITIGATION_RETPOLINE) && fault.is_tdp)
+		r = kvm_tdp_page_fault(vcpu, &fault);
+	else
+		r = vcpu->arch.mmu->page_fault(vcpu, &fault);
+
+	if (r == RET_PF_EMULATE && fault.is_private) {
+		kvm_mmu_prepare_memory_fault_exit(vcpu, &fault);
+		r = -EFAULT;
+	}
+
+	if (fault.write_fault_to_shadow_pgtable && emulation_type)
+		*emulation_type |= EMULTYPE_WRITE_PF_TO_SP;
+
+	return r;
+}
+
+static inline int kvm_mmu_do_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
+					u64 err, bool prefetch, int *emulation_type)
+{
+	int r;
+
 	/*
 	 * Async #PF "faults", a.k.a. prefetch faults, are not faults from the
 	 * guest perspective and have already been counted at the time of the
@@ -326,18 +347,7 @@  static inline int kvm_mmu_do_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
 	if (!prefetch)
 		vcpu->stat.pf_taken++;
 
-	if (IS_ENABLED(CONFIG_MITIGATION_RETPOLINE) && fault.is_tdp)
-		r = kvm_tdp_page_fault(vcpu, &fault);
-	else
-		r = vcpu->arch.mmu->page_fault(vcpu, &fault);
-
-	if (r == RET_PF_EMULATE && fault.is_private) {
-		kvm_mmu_prepare_memory_fault_exit(vcpu, &fault);
-		return -EFAULT;
-	}
-
-	if (fault.write_fault_to_shadow_pgtable && emulation_type)
-		*emulation_type |= EMULTYPE_WRITE_PF_TO_SP;
+	r = __kvm_mmu_do_page_fault(vcpu, cr2_or_gpa, err, prefetch, emulation_type);
 
 	/*
 	 * Similar to above, prefetch faults aren't truly spurious, and the