[PATCH V13 02/14] KVM: x86: Fix Intel PT IA32_RTIT_CTL MSR validation

Adrian Hunter
2024-10-14T10:52:11Z

Fix KVM IA32_RTIT_CTL MSR validation logic so that if RTIT_CTL_TRACEEN
bit is cleared, then other bits are allowed to change also. For example,
writing 0 to IA32_RTIT_CTL in order to stop tracing, is valid.

Fixes: bf8c55d8dc09 ("KVM: x86: Implement Intel PT MSRs read/write emulation")
Cc: stable@vger.kernel.org
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
---
arch/x86/kvm/vmx/vmx.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 1a4438358c5e..eaf4965ac6df 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -1635,7 +1635,8 @@ static int vmx_rtit_ctl_check(struct kvm_vcpu *vcpu, u64 data)
* result in a #GP unless the same write also clears TraceEn.
*/
if ((vmx->pt_desc.guest.ctl & RTIT_CTL_TRACEEN) &&
- ((vmx->pt_desc.guest.ctl ^ data) & ~RTIT_CTL_TRACEEN))
+ (data & RTIT_CTL_TRACEEN) &&
+ data != vmx->pt_desc.guest.ctl)
return 1;

/*
--
2.43.0