linux-kernel - [PATCH 07/22] KVM: x86: Store gpa as gpa_t, not unsigned long, when unprotecting for retry

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Message-ID: <20240809190319.1710470-8-seanjc@google.com>
Date: Fri,  9 Aug 2024 12:03:04 -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 07/22] KVM: x86: Store gpa as gpa_t, not unsigned long, when
 unprotecting for retry

Store the gpa used to unprotect the faulting gfn for retry as a gpa_t, not
an unsigned long.  This fixes a bug where 32-bit KVM would unprotect and
retry the wrong gfn if the gpa had bits 63:32!=0.  In practice, this bug
is functionally benign, as unprotecting the wrong gfn is purely a
performance issue (thanks to the anti-infinite-loop logic).  And of course,
almost no one runs 32-bit KVM these days.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/x86.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 372ed3842732..4c3493ffce0b 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8934,7 +8934,8 @@ static bool retry_instruction(struct x86_emulate_ctxt *ctxt,
 			      gpa_t cr2_or_gpa,  int emulation_type)
 {
 	struct kvm_vcpu *vcpu = emul_to_vcpu(ctxt);
-	unsigned long last_retry_eip, last_retry_addr, gpa = cr2_or_gpa;
+	unsigned long last_retry_eip, last_retry_addr;
+	gpa_t gpa = cr2_or_gpa;
 
 	last_retry_eip = vcpu->arch.last_retry_eip;
 	last_retry_addr = vcpu->arch.last_retry_addr;
-- 
2.46.0.76.ge559c4bf1a-goog