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KVM: TDX: Save and restore IA32_DEBUGCTL

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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@intel.com>
Message-ID: <20250129095902.16391-12-adrian.hunter@intel.com>
Reviewed-by: Xiayao Li <xiaoyao.li@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Adrian Hunter 2025-01-29 11:59:00 +02:00 • committed by Paolo Bonzini
parent 6d415778f1
commit 8af0990375
1 changed files with 10 additions and 1 deletions
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11
arch/x86/kvm/vmx/tdx.c
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@ -688,6 +688,8 @@ void tdx_prepare_switch_to_guest(struct kvm_vcpu *vcpu)
else else
vt->msr_host_kernel_gs_base = read_msr(MSR_KERNEL_GS_BASE); vt->msr_host_kernel_gs_base = read_msr(MSR_KERNEL_GS_BASE);
vt->host_debugctlmsr = get_debugctlmsr();
vt->guest_state_loaded = true; vt->guest_state_loaded = true;
} }
@ -831,11 +833,15 @@ static void tdx_load_host_xsave_state(struct kvm_vcpu *vcpu)
if (kvm_host.xss != (kvm_tdx->xfam & kvm_caps.supported_xss)) if (kvm_host.xss != (kvm_tdx->xfam & kvm_caps.supported_xss))
wrmsrl(MSR_IA32_XSS, kvm_host.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) fastpath_t tdx_vcpu_run(struct kvm_vcpu *vcpu, bool force_immediate_exit)
{ {
struct vcpu_tdx *tdx = to_tdx(vcpu); struct vcpu_tdx *tdx = to_tdx(vcpu);
struct vcpu_vt *vt = to_vt(vcpu);
/* /*
* force_immediate_exit requires vCPU entering for events injection with * force_immediate_exit requires vCPU entering for events injection with
@ -851,6 +857,9 @@ fastpath_t tdx_vcpu_run(struct kvm_vcpu *vcpu, bool force_immediate_exit)
tdx_vcpu_enter_exit(vcpu); tdx_vcpu_enter_exit(vcpu);
if (vt->host_debugctlmsr & ~TDX_DEBUGCTL_PRESERVED)
update_debugctlmsr(vt->host_debugctlmsr);
tdx_load_host_xsave_state(vcpu); tdx_load_host_xsave_state(vcpu);
tdx->guest_entered = true; tdx->guest_entered = true;