[PATCH 1/3] KVM: x86: Fix Intel PT IA32_RTIT_CTL MSR validation

[Adrian Hunter <adrian.hunter@intel.com>]

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 f18c2d8c7476..3f1e3be552c0 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -1639,7 +1639,8 @@ 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