diff mbox series

[10/22] KVM: x86/mmu: Replace PFERR_NESTED_GUEST_PAGE with a more descriptive helper

Message ID 20240809190319.1710470-11-seanjc@google.com (mailing list archive)
State New, archived
Headers show
Series KVM: x86: Fix multiple #PF RO infinite loop bugs | expand

Commit Message

Sean Christopherson Aug. 9, 2024, 7:03 p.m. UTC 
Drop the globally visible PFERR_NESTED_GUEST_PAGE and replace it with a
more appropriately named is_write_to_guest_page_table().  The macro name
is misleading, because while all nNPT walks match PAGE|WRITE|PRESENT, the
reverse is not true.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/include/asm/kvm_host.h |  4 ----
 arch/x86/kvm/mmu/mmu.c          | 10 ++++++++--
 2 files changed, 8 insertions(+), 6 deletions(-)

Comments

Paolo Bonzini Aug. 14, 2024, 5:32 p.m. UTC | #1 
On 8/9/24 21:03, Sean Christopherson wrote:
> -	if (direct &&
> -	    (error_code & PFERR_NESTED_GUEST_PAGE) == PFERR_NESTED_GUEST_PAGE &&
> +	if (direct && (is_write_to_guest_page_table(error_code)) &&

Too many parentheses. :)

Maybe put it before patch 3 if we decide not to Cc: stable?  Or even 
squash it in there?

Paolo
Sean Christopherson Aug. 15, 2024, 2:10 p.m. UTC | #2 
On Wed, Aug 14, 2024, Paolo Bonzini wrote:
> On 8/9/24 21:03, Sean Christopherson wrote:
> > -	if (direct &&
> > -	    (error_code & PFERR_NESTED_GUEST_PAGE) == PFERR_NESTED_GUEST_PAGE &&
> > +	if (direct && (is_write_to_guest_page_table(error_code)) &&
> 
> Too many parentheses. :)
> 
> Maybe put it before patch 3 if we decide not to Cc: stable?

Ya, I'll do this.
diff mbox series

Patch

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 10b47c310ff9..25a3d84ca5e2 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -280,10 +280,6 @@  enum x86_intercept_stage;
 #define PFERR_PRIVATE_ACCESS   BIT_ULL(49)
 #define PFERR_SYNTHETIC_MASK   (PFERR_IMPLICIT_ACCESS | PFERR_PRIVATE_ACCESS)
 
-#define PFERR_NESTED_GUEST_PAGE (PFERR_GUEST_PAGE_MASK |	\
-				 PFERR_WRITE_MASK |		\
-				 PFERR_PRESENT_MASK)
-
 /* apic attention bits */
 #define KVM_APIC_CHECK_VAPIC	0
 /*
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 358294889baa..065bb6180988 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -5980,6 +5980,13 @@  void kvm_mmu_track_write(struct kvm_vcpu *vcpu, gpa_t gpa, const u8 *new,
 	write_unlock(&vcpu->kvm->mmu_lock);
 }
 
+static bool is_write_to_guest_page_table(u64 error_code)
+{
+	const u64 mask = PFERR_GUEST_PAGE_MASK | PFERR_WRITE_MASK | PFERR_PRESENT_MASK;
+
+	return (error_code & mask) == mask;
+}
+
 static int kvm_mmu_write_protect_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
 				       u64 error_code, int *emulation_type)
 {
@@ -6026,8 +6033,7 @@  static int kvm_mmu_write_protect_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
 	 * write-fault is due to something else entirely, i.e. KVM needs to
 	 * emulate, as resuming the guest will put it into an infinite loop.
 	 */
-	if (direct &&
-	    (error_code & PFERR_NESTED_GUEST_PAGE) == PFERR_NESTED_GUEST_PAGE &&
+	if (direct && (is_write_to_guest_page_table(error_code)) &&
 	    kvm_mmu_unprotect_gfn_and_retry(vcpu, cr2_or_gpa))
 		return RET_PF_FIXED;