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

[ Upstream commit fb71c795935652fa20eaf9517ca9547f5af99a76 ]

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>
[sean: resolve minor syntatic conflict in vmx_vcpu_load()]
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 6db42ee820320da6d645981efa2166755807ff2f..555c7bf35e28178ef8f428cba46b5738b87cb3ff 100644 (file)
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -677,6 +677,7 @@ 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;

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 7b87fbc69b21113de1395392a2a801973f1411f0..c24da2cff2081ea5ed164444377162dff60c08ad 100644 (file)
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -1418,13 +1418,9 @@ void vmx_vcpu_load_vmcs(struct kvm_vcpu *vcpu, int cpu,
  */
 static void vmx_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 {
-       struct vcpu_vmx *vmx = to_vmx(vcpu);
-
        vmx_vcpu_load_vmcs(vcpu, cpu, NULL);
 
        vmx_vcpu_pi_load(vcpu, cpu);
-
-       vmx->host_debugctlmsr = get_debugctlmsr();
 }
 
 static void vmx_vcpu_put(struct kvm_vcpu *vcpu)
@@ -7275,8 +7271,8 @@ static fastpath_t vmx_vcpu_run(struct kvm_vcpu *vcpu)
        }
 
        /* 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
        /*

diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
index 8b4b149bd9c1ade3ccc379019da53639cd0a4b67..357819872d807a9defbb83a35384a5835bba7e3b 100644 (file)
--- a/arch/x86/kvm/vmx/vmx.h
+++ b/arch/x86/kvm/vmx/vmx.h
@@ -352,8 +352,6 @@ 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

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index a6dc8f662fa40517e5eea8e1b37b228ffadfed30..ba24bb50af57355b26f00b65f9e0492773c58e71 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4742,6 +4742,7 @@ 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)) {