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.

Reviewed-by: Yuan Yao <yuan.yao@intel.com>
Link: https://lore.kernel.org/r/20240831001538.336683-8-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 760d455f77ac9d2e66435e1c5d43812e5ddc7195..d26e107225f7fb80499ac0ab4f398d03ff14fa04 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8932,7 +8932,8 @@ 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;