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KVM: x86: Snapshot the host's DEBUGCTL in common x86

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Move KVM's snapshot of DEBUGCTL to kvm_vcpu_arch and take the snapshot in
common x86, so that SVM can also use the snapshot.

Opportunistically change the field to a u64.  While bits 63:32 are reserved
on AMD, not mentioned at all in Intel's SDM, and managed as an "unsigned
long" by the kernel, DEBUGCTL is an MSR and therefore a 64-bit value.

Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Cc: stable@vger.kernel.org
Reviewed-and-tested-by: Ravi Bangoria <ravi.bangoria@amd.com>
Link: https://lore.kernel.org/r/20250227222411.3490595-4-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Sean Christopherson 2025-02-27 14:24:08 -08:00
parent d0eac42f5c
commit fb71c79593
4 changed files with 4 additions and 8 deletions
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1
arch/x86/include/asm/kvm_host.h
View file

@ -780,6 +780,7 @@ struct kvm_vcpu_arch {
u32 pkru;
u32 hflags;
u64 efer;
u64 host_debugctl;
u64 apic_base;
struct kvm_lapic *apic; /* kernel irqchip context */
bool load_eoi_exitmap_pending;

8
arch/x86/kvm/vmx/vmx.c
View file

@ -1514,16 +1514,12 @@ void vmx_vcpu_load_vmcs(struct kvm_vcpu *vcpu, int cpu,
*/
void vmx_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
if (vcpu->scheduled_out && !kvm_pause_in_guest(vcpu->kvm))
shrink_ple_window(vcpu);
vmx_vcpu_load_vmcs(vcpu, cpu, NULL);
vmx_vcpu_pi_load(vcpu, cpu);
vmx->host_debugctlmsr = get_debugctlmsr();
}
void vmx_vcpu_put(struct kvm_vcpu *vcpu)
@ -7458,8 +7454,8 @@ fastpath_t vmx_vcpu_run(struct kvm_vcpu *vcpu, bool force_immediate_exit)
}
/* MSR_IA32_DEBUGCTLMSR is zeroed on vmexit. Restore it if needed */
if (vmx->host_debugctlmsr)
update_debugctlmsr(vmx->host_debugctlmsr);
if (vcpu->arch.host_debugctl)
update_debugctlmsr(vcpu->arch.host_debugctl);
#ifndef CONFIG_X86_64
/*

2
arch/x86/kvm/vmx/vmx.h
View file

@ -340,8 +340,6 @@ struct vcpu_vmx {
/* apic deadline value in host tsc */
u64 hv_deadline_tsc;
unsigned long host_debugctlmsr;
/*
* Only bits masked by msr_ia32_feature_control_valid_bits can be set in
* msr_ia32_feature_control. FEAT_CTL_LOCKED is always included

1
arch/x86/kvm/x86.c
View file

@ -4968,6 +4968,7 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
/* Save host pkru register if supported */
vcpu->arch.host_pkru = read_pkru();
vcpu->arch.host_debugctl = get_debugctlmsr();
/* Apply any externally detected TSC adjustments (due to suspend) */
if (unlikely(vcpu->arch.tsc_offset_adjustment)) {