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

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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>
This commit is contained in:
Sean Christopherson 2026-02-13 17:26:53 -08:00
parent 920da4f755
commit 32d76cdfa1
3 changed files with 66 additions and 27 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
arch/x86/include/asm/virt.h
View File

@ -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

34
arch/x86/kvm/svm/svm.c
View File

@ -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.
*

53
arch/x86/virt/hw.c
View File

@ -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();