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: 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>

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 0b7af5902ff757238dd8a91fa21979203a88b191..32ae3aa50c7e386894885c5af3e9ed0a4d0bb7fd 100644 (file)
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -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;

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 6c56d5235f0f3e18c9476f433f7b783ba600ea3c..3b92f893b2392a0027a917de17831dcf9d41c4f5 100644 (file)
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -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
        /*

diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
index 8b111ce1087c7daa5e2d2b7b9e6ae4e208193f57..951e44dc9d0ea3caafeddc8e69a25cb9ebd6e2eb 100644 (file)
--- a/arch/x86/kvm/vmx/vmx.h
+++ b/arch/x86/kvm/vmx/vmx.h
@@ -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

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 02159c967d29e5f9134a9ceba8f9ebffd9fa96f6..5c6fd0edc41f4d481a363fffa651990716cfc153 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -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)) {