linux-kernel - [PATCH 14/22] KVM: x86/mmu: Always walk guest PTEs with WRITE access when unprotecting

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Message-ID: <20240809190319.1710470-15-seanjc@google.com>
Date: Fri,  9 Aug 2024 12:03:11 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Peter Gonda <pgonda@...gle.com>, Michael Roth <michael.roth@....com>, 
	Vishal Annapurve <vannapurve@...gle.com>, Ackerly Tng <ackerleytng@...gle.com>
Subject: [PATCH 14/22] KVM: x86/mmu: Always walk guest PTEs with WRITE access
 when unprotecting

When getting a gpa from a gva to unprotect the associated gfn when an
event is awating reinjection, walk the guest PTEs for WRITE as there's no
point in unprotecting the gfn if the guest is unable to write the page,
i.e. if write-protection can't trigger emulation.

Note, the entire flow should be guarded on the access being a write, and
even better should be conditioned on actually triggering a write-protect
fault.  This will be addressed in a future commit.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/mmu/mmu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index a5d1f6232f8c..f64ad36ca9e0 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -2761,7 +2761,7 @@ static int kvm_mmu_unprotect_page_virt(struct kvm_vcpu *vcpu, gva_t gva)
 	if (vcpu->arch.mmu->root_role.direct)
 		return 0;
 
-	gpa = kvm_mmu_gva_to_gpa_read(vcpu, gva, NULL);
+	gpa = kvm_mmu_gva_to_gpa_write(vcpu, gva, NULL);
 	if (gpa == INVALID_GPA)
 		return 0;
 
-- 
2.46.0.76.ge559c4bf1a-goog