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KVM: SVM: Implement VIRT_SPEC_CTRL support for SSBD

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Expose the new virtualized architectural mechanism, VIRT_SSBD, for using
speculative store bypass disable (SSBD) under SVM.  This will allow guests
to use SSBD on hardware that uses non-architectural mechanisms for enabling
SSBD.

[ tglx: Folded the migration fixup from Paolo Bonzini ]

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Tom Lendacky 2018-05-10 22:06:39 +02:00 committed by Thomas Gleixner
parent 47c61b3955
commit bc226f07dc
6 changed files with 50 additions and 18 deletions
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2
arch/x86/include/asm/kvm_host.h
View File

@ -924,7 +924,7 @@ struct kvm_x86_ops {
int (*hardware_setup)(void); /* __init */
void (*hardware_unsetup)(void); /* __exit */
bool (*cpu_has_accelerated_tpr)(void);
bool (*cpu_has_high_real_mode_segbase)(void);
bool (*has_emulated_msr)(int index);
void (*cpuid_update)(struct kvm_vcpu *vcpu);
struct kvm *(*vm_alloc)(void);

3
arch/x86/kernel/cpu/common.c
View File

@ -767,7 +767,8 @@ static void init_speculation_control(struct cpuinfo_x86 *c)
if (cpu_has(c, X86_FEATURE_INTEL_STIBP))
set_cpu_cap(c, X86_FEATURE_STIBP);
if (cpu_has(c, X86_FEATURE_SPEC_CTRL_SSBD))
if (cpu_has(c, X86_FEATURE_SPEC_CTRL_SSBD) ||
cpu_has(c, X86_FEATURE_VIRT_SSBD))
set_cpu_cap(c, X86_FEATURE_SSBD);
if (cpu_has(c, X86_FEATURE_AMD_IBRS)) {

11
arch/x86/kvm/cpuid.c
View File

@ -379,7 +379,7 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
/* cpuid 0x80000008.ebx */
const u32 kvm_cpuid_8000_0008_ebx_x86_features =
F(AMD_IBPB) | F(AMD_IBRS);
F(AMD_IBPB) | F(AMD_IBRS) | F(VIRT_SSBD);
/* cpuid 0xC0000001.edx */
const u32 kvm_cpuid_C000_0001_edx_x86_features =
@ -647,13 +647,20 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
g_phys_as = phys_as;
entry->eax = g_phys_as | (virt_as << 8);
entry->edx = 0;
/* IBRS and IBPB aren't necessarily present in hardware cpuid */
/*
* IBRS, IBPB and VIRT_SSBD aren't necessarily present in
* hardware cpuid
*/
if (boot_cpu_has(X86_FEATURE_AMD_IBPB))
entry->ebx |= F(AMD_IBPB);
if (boot_cpu_has(X86_FEATURE_AMD_IBRS))
entry->ebx |= F(AMD_IBRS);
if (boot_cpu_has(X86_FEATURE_VIRT_SSBD))
entry->ebx |= F(VIRT_SSBD);
entry->ebx &= kvm_cpuid_8000_0008_ebx_x86_features;
cpuid_mask(&entry->ebx, CPUID_8000_0008_EBX);
if (boot_cpu_has(X86_FEATURE_LS_CFG_SSBD))
entry->ebx |= F(VIRT_SSBD);
break;
}
case 0x80000019:

21
arch/x86/kvm/svm.c
View File

@ -4120,6 +4120,13 @@ static int svm_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
msr_info->data = svm->spec_ctrl;
break;
case MSR_AMD64_VIRT_SPEC_CTRL:
if (!msr_info->host_initiated &&
!guest_cpuid_has(vcpu, X86_FEATURE_VIRT_SSBD))
return 1;
msr_info->data = svm->virt_spec_ctrl;
break;
case MSR_F15H_IC_CFG: {
int family, model;
@ -4251,6 +4258,16 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr)
break;
set_msr_interception(svm->msrpm, MSR_IA32_PRED_CMD, 0, 1);
break;
case MSR_AMD64_VIRT_SPEC_CTRL:
if (!msr->host_initiated &&
!guest_cpuid_has(vcpu, X86_FEATURE_VIRT_SSBD))
return 1;
if (data & ~SPEC_CTRL_SSBD)
return 1;
svm->virt_spec_ctrl = data;
break;
case MSR_STAR:
svm->vmcb->save.star = data;
break;
@ -5791,7 +5808,7 @@ static bool svm_cpu_has_accelerated_tpr(void)
return false;
}
static bool svm_has_high_real_mode_segbase(void)
static bool svm_has_emulated_msr(int index)
{
return true;
}
@ -7017,7 +7034,7 @@ static struct kvm_x86_ops svm_x86_ops __ro_after_init = {
.hardware_enable = svm_hardware_enable,
.hardware_disable = svm_hardware_disable,
.cpu_has_accelerated_tpr = svm_cpu_has_accelerated_tpr,
.cpu_has_high_real_mode_segbase = svm_has_high_real_mode_segbase,
.has_emulated_msr = svm_has_emulated_msr,
.vcpu_create = svm_create_vcpu,
.vcpu_free = svm_free_vcpu,

18
arch/x86/kvm/vmx.c
View File

@ -9477,9 +9477,21 @@ static void vmx_handle_external_intr(struct kvm_vcpu *vcpu)
}
STACK_FRAME_NON_STANDARD(vmx_handle_external_intr);
static bool vmx_has_high_real_mode_segbase(void)
static bool vmx_has_emulated_msr(int index)
{
return enable_unrestricted_guest || emulate_invalid_guest_state;
switch (index) {
case MSR_IA32_SMBASE:
/*
* We cannot do SMM unless we can run the guest in big
* real mode.
*/
return enable_unrestricted_guest || emulate_invalid_guest_state;
case MSR_AMD64_VIRT_SPEC_CTRL:
/* This is AMD only. */
return false;
default:
return true;
}
}
static bool vmx_mpx_supported(void)
@ -12625,7 +12637,7 @@ static struct kvm_x86_ops vmx_x86_ops __ro_after_init = {
.hardware_enable = hardware_enable,
.hardware_disable = hardware_disable,
.cpu_has_accelerated_tpr = report_flexpriority,
.cpu_has_high_real_mode_segbase = vmx_has_high_real_mode_segbase,
.has_emulated_msr = vmx_has_emulated_msr,
.vm_init = vmx_vm_init,
.vm_alloc = vmx_vm_alloc,

13
arch/x86/kvm/x86.c
View File

@ -1058,6 +1058,7 @@ static u32 emulated_msrs[] = {
MSR_SMI_COUNT,
MSR_PLATFORM_INFO,
MSR_MISC_FEATURES_ENABLES,
MSR_AMD64_VIRT_SPEC_CTRL,
};
static unsigned num_emulated_msrs;
@ -2903,7 +2904,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
* fringe case that is not enabled except via specific settings
* of the module parameters.
*/
r = kvm_x86_ops->cpu_has_high_real_mode_segbase();
r = kvm_x86_ops->has_emulated_msr(MSR_IA32_SMBASE);
break;
case KVM_CAP_VAPIC:
r = !kvm_x86_ops->cpu_has_accelerated_tpr();
@ -4603,14 +4604,8 @@ static void kvm_init_msr_list(void)
num_msrs_to_save = j;
for (i = j = 0; i < ARRAY_SIZE(emulated_msrs); i++) {
switch (emulated_msrs[i]) {
case MSR_IA32_SMBASE:
if (!kvm_x86_ops->cpu_has_high_real_mode_segbase())
continue;
break;
default:
break;
}
if (!kvm_x86_ops->has_emulated_msr(emulated_msrs[i]))
continue;
if (j < i)
emulated_msrs[j] = emulated_msrs[i];