KVM: SVM: Move core EFER.SVME enablement to kernel

Move the innermost EFER.SVME logic out of KVM and into to core x86 to land
the SVM support alongside VMX support.  This will allow providing a more
unified API from the kernel to KVM, and will allow moving the bulk of the
emergency disabling insanity out of KVM without having a weird split
between kernel and KVM for SVM vs. VMX.

No functional change intended.

Tested-by: Chao Gao <chao.gao@intel.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Tested-by: Sagi Shahar <sagis@google.com>
Link: https://patch.msgid.link/20260214012702.2368778-8-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

diff --git a/arch/x86/include/asm/virt.h b/arch/x86/include/asm/virt.h
index cca0210a5c16412aabf933e912078bd3c79bc488..9a0753eaa20ce3179c4c3001a3152e14d14d6c02 100644 (file)
--- a/arch/x86/include/asm/virt.h
+++ b/arch/x86/include/asm/virt.h
@@ -15,6 +15,12 @@ int x86_vmx_disable_virtualization_cpu(void);
 void x86_vmx_emergency_disable_virtualization_cpu(void);
 #endif
 
+#if IS_ENABLED(CONFIG_KVM_AMD)
+int x86_svm_enable_virtualization_cpu(void);
+int x86_svm_disable_virtualization_cpu(void);
+void x86_svm_emergency_disable_virtualization_cpu(void);
+#endif
+
 #else
 static __always_inline void x86_virt_init(void) {}
 #endif

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 0ae66c770ebc681e8f466c25bf276aa60cfefd43..fc08450cb4b7803917232ec9c59139e195d177aa 100644 (file)
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -478,27 +478,9 @@ static __always_inline struct sev_es_save_area *sev_es_host_save_area(struct svm
        return &sd->save_area->host_sev_es_save;
 }
 
-static inline void kvm_cpu_svm_disable(void)
-{
-       uint64_t efer;
-
-       wrmsrq(MSR_VM_HSAVE_PA, 0);
-       rdmsrq(MSR_EFER, efer);
-       if (efer & EFER_SVME) {
-               /*
-                * Force GIF=1 prior to disabling SVM, e.g. to ensure INIT and
-                * NMI aren't blocked.
-                */
-               stgi();
-               wrmsrq(MSR_EFER, efer & ~EFER_SVME);
-       }
-}
-
 static void svm_emergency_disable_virtualization_cpu(void)
 {
-       virt_rebooting = true;
-
-       kvm_cpu_svm_disable();
+       wrmsrq(MSR_VM_HSAVE_PA, 0);
 }
 
 static void svm_disable_virtualization_cpu(void)
@@ -507,7 +489,8 @@ static void svm_disable_virtualization_cpu(void)
        if (tsc_scaling)
                __svm_write_tsc_multiplier(SVM_TSC_RATIO_DEFAULT);
 
-       kvm_cpu_svm_disable();
+       x86_svm_disable_virtualization_cpu();
+       wrmsrq(MSR_VM_HSAVE_PA, 0);
 
        amd_pmu_disable_virt();
 }
@@ -516,12 +499,12 @@ static int svm_enable_virtualization_cpu(void)
 {
 
        struct svm_cpu_data *sd;
-       uint64_t efer;
        int me = raw_smp_processor_id();
+       int r;
 
-       rdmsrq(MSR_EFER, efer);
-       if (efer & EFER_SVME)
-               return -EBUSY;
+       r = x86_svm_enable_virtualization_cpu();
+       if (r)
+               return r;
 
        sd = per_cpu_ptr(&svm_data, me);
        sd->asid_generation = 1;
@@ -529,8 +512,6 @@ static int svm_enable_virtualization_cpu(void)
        sd->next_asid = sd->max_asid + 1;
        sd->min_asid = max_sev_asid + 1;
 
-       wrmsrq(MSR_EFER, efer | EFER_SVME);
-
        wrmsrq(MSR_VM_HSAVE_PA, sd->save_area_pa);
 
        if (static_cpu_has(X86_FEATURE_TSCRATEMSR)) {
@@ -541,7 +522,6 @@ static int svm_enable_virtualization_cpu(void)
                __svm_write_tsc_multiplier(SVM_TSC_RATIO_DEFAULT);
        }
 
-
        /*
         * Get OSVW bits.
         *

diff --git a/arch/x86/virt/hw.c b/arch/x86/virt/hw.c
index dc426c2bc24adfd3b238e0b78687cad004e796db..014e9dfab805bb434705db4ef496c486863fec49 100644 (file)
--- a/arch/x86/virt/hw.c
+++ b/arch/x86/virt/hw.c
@@ -163,6 +163,59 @@ static __init int x86_vmx_init(void)
 static __init int x86_vmx_init(void) { return -EOPNOTSUPP; }
 #endif
 
+#if IS_ENABLED(CONFIG_KVM_AMD)
+int x86_svm_enable_virtualization_cpu(void)
+{
+       u64 efer;
+
+       if (!cpu_feature_enabled(X86_FEATURE_SVM))
+               return -EOPNOTSUPP;
+
+       rdmsrq(MSR_EFER, efer);
+       if (efer & EFER_SVME)
+               return -EBUSY;
+
+       wrmsrq(MSR_EFER, efer | EFER_SVME);
+       return 0;
+}
+EXPORT_SYMBOL_FOR_KVM(x86_svm_enable_virtualization_cpu);
+
+int x86_svm_disable_virtualization_cpu(void)
+{
+       int r = -EIO;
+       u64 efer;
+
+       /*
+        * Force GIF=1 prior to disabling SVM, e.g. to ensure INIT and
+        * NMI aren't blocked.
+        */
+       asm goto("1: stgi\n\t"
+                _ASM_EXTABLE(1b, %l[fault])
+                ::: "memory" : fault);
+       r = 0;
+
+fault:
+       rdmsrq(MSR_EFER, efer);
+       wrmsrq(MSR_EFER, efer & ~EFER_SVME);
+       return r;
+}
+EXPORT_SYMBOL_FOR_KVM(x86_svm_disable_virtualization_cpu);
+
+void x86_svm_emergency_disable_virtualization_cpu(void)
+{
+       u64 efer;
+
+       virt_rebooting = true;
+
+       rdmsrq(MSR_EFER, efer);
+       if (!(efer & EFER_SVME))
+               return;
+
+       x86_svm_disable_virtualization_cpu();
+}
+EXPORT_SYMBOL_FOR_KVM(x86_svm_emergency_disable_virtualization_cpu);
+#endif
+
 void __init x86_virt_init(void)
 {
        x86_vmx_init();