From: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Save the IA32_DEBUGCTL MSR before entering a TDX VCPU and restore it
afterwards. The TDX Module preserves bits 1, 12, and 14, so if no
other bits are set, no restore is done.
Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Message-ID: <20250129095902.16391-12-adrian.hunter@xxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
---
arch/x86/kvm/vmx/tdx.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
index 5625b0801ce8..25972e12504b 100644
--- a/arch/x86/kvm/vmx/tdx.c
+++ b/arch/x86/kvm/vmx/tdx.c
@@ -683,6 +683,8 @@ void tdx_prepare_switch_to_guest(struct kvm_vcpu *vcpu)
else
vt->msr_host_kernel_gs_base = read_msr(MSR_KERNEL_GS_BASE);
+ vt->host_debugctlmsr = get_debugctlmsr();
+
vt->guest_state_loaded = true;
}
@@ -826,11 +828,15 @@ static void tdx_load_host_xsave_state(struct kvm_vcpu *vcpu)
if (kvm_host.xss != (kvm_tdx->xfam & kvm_caps.supported_xss))
wrmsrl(MSR_IA32_XSS, kvm_host.xss);
}
-EXPORT_SYMBOL_GPL(kvm_load_host_xsave_state);
+
+#define TDX_DEBUGCTL_PRESERVED (DEBUGCTLMSR_BTF | \
+ DEBUGCTLMSR_FREEZE_PERFMON_ON_PMI | \
+ DEBUGCTLMSR_FREEZE_IN_SMM)
fastpath_t tdx_vcpu_run(struct kvm_vcpu *vcpu, bool force_immediate_exit)
{
struct vcpu_tdx *tdx = to_tdx(vcpu);
+ struct vcpu_vt *vt = to_vt(vcpu);
/*
* force_immediate_exit requires vCPU entering for events injection with
@@ -846,6 +852,9 @@ fastpath_t tdx_vcpu_run(struct kvm_vcpu *vcpu, bool force_immediate_exit)
tdx_vcpu_enter_exit(vcpu);
+ if (vt->host_debugctlmsr & ~TDX_DEBUGCTL_PRESERVED)
+ update_debugctlmsr(vt->host_debugctlmsr);
+
tdx_load_host_xsave_state(vcpu);
tdx->guest_entered = true;
--
2.43.5
