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

commit fb71c795935652fa20eaf9517ca9547f5af99a76 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 8499b9cb9c826382a891e93b1323dfb6a8ba5f24..e4dd840e0becd4d675fe003f5df9c6f91c1dc6bb 100644 (file)
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -761,6 +761,7 @@ 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 1af30e3472cdd97ed1fef070e53d0e77ebe3e6bb..a3d45b01dbadf341b7363cab07a4f7115d007095 100644 (file)
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -1515,16 +1515,12 @@ 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)
@@ -7454,8 +7450,8 @@ 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
        /*

diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
index 41bf59bbc6426c71977179b547fa4d85af95ff4b..cf57fbf12104f5eaffec6b5143fc12bea975eba9 100644 (file)
--- a/arch/x86/kvm/vmx/vmx.h
+++ b/arch/x86/kvm/vmx/vmx.h
@@ -339,8 +339,6 @@ 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 b67a2f46e40b05af090878063347d26e9f69caad..59d3bfd73a0679ce5cc27bce53f136b926ffd5e0 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4993,6 +4993,7 @@ 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)) {