Commit fb71c795 authored by Sean Christopherson's avatar Sean Christopherson
Browse files

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



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: default avatarXiaoyao Li <xiaoyao.li@intel.com>
Cc: stable@vger.kernel.org
Reviewed-and-tested-by: default avatarRavi Bangoria <ravi.bangoria@amd.com>
Link: https://lore.kernel.org/r/20250227222411.3490595-4-seanjc@google.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent d0eac42f

arch/x86/include/asm/kvm_host.h

+1 −0
Original line number Diff line number Diff line
@@ -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;

arch/x86/kvm/vmx/vmx.c

+2 −6
Original line number Diff line number Diff line
@@ -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

	/*

arch/x86/kvm/vmx/vmx.h

+0 −2
Original line number Diff line number Diff line
@@ -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

arch/x86/kvm/x86.c

+1 −0
Original line number Diff line number Diff line
@@ -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)) {