KVM: CPUID: add support for supervisor states
Current CPUID 0xd enumeration code does not support supervisor
states, because KVM only supports setting IA32_XSS to zero.
Change it instead to use a new variable supported_xss, to be
set from the hardware_setup callback which is in charge of CPU
capabilities.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index cc8b24b..78d461b 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -642,15 +642,22 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
cpuid_entry_override(entry, CPUID_D_1_EAX);
if (entry->eax & (F(XSAVES)|F(XSAVEC)))
- entry->ebx = xstate_required_size(supported_xcr0, true);
- else
+ entry->ebx = xstate_required_size(supported_xcr0 | supported_xss,
+ true);
+ else {
+ WARN_ON_ONCE(supported_xss != 0);
entry->ebx = 0;
- /* Saving XSS controlled state via XSAVES isn't supported. */
- entry->ecx = 0;
- entry->edx = 0;
+ }
+ entry->ecx &= supported_xss;
+ entry->edx &= supported_xss >> 32;
for (i = 2; i < 64; ++i) {
- if (!(supported_xcr0 & BIT_ULL(i)))
+ bool s_state;
+ if (supported_xcr0 & BIT_ULL(i))
+ s_state = false;
+ else if (supported_xss & BIT_ULL(i))
+ s_state = true;
+ else
continue;
entry = do_host_cpuid(array, function, i);
@@ -659,17 +666,16 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
/*
* The supported check above should have filtered out
- * invalid sub-leafs as well as sub-leafs managed by
- * IA32_XSS MSR. Only XCR0-managed sub-leafs should
+ * invalid sub-leafs. Only valid sub-leafs should
* reach this point, and they should have a non-zero
- * save state size.
+ * save state size. Furthermore, check whether the
+ * processor agrees with supported_xcr0/supported_xss
+ * on whether this is an XCR0- or IA32_XSS-managed area.
*/
- if (WARN_ON_ONCE(!entry->eax || (entry->ecx & 1))) {
+ if (WARN_ON_ONCE(!entry->eax || (entry->ecx & 0x1) != s_state)) {
--array->nent;
continue;
}
-
- entry->ecx = 0;
entry->edx = 0;
}
break;
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index c6e9910..4dca357 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1371,6 +1371,8 @@ static __init void svm_set_cpu_caps(void)
{
kvm_set_cpu_caps();
+ supported_xss = 0;
+
/* CPUID 0x80000001 and 0x8000000A (SVM features) */
if (nested) {
kvm_cpu_cap_set(X86_FEATURE_SVM);
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index e91a84b..8001070b 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -7126,6 +7126,7 @@ static __init void vmx_set_cpu_caps(void)
kvm_cpu_cap_set(X86_FEATURE_UMIP);
/* CPUID 0xD.1 */
+ supported_xss = 0;
if (!vmx_xsaves_supported())
kvm_cpu_cap_clear(X86_FEATURE_XSAVES);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index d2f1b47..96e897d 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -190,6 +190,8 @@ u64 __read_mostly host_efer;
EXPORT_SYMBOL_GPL(host_efer);
static u64 __read_mostly host_xss;
+u64 __read_mostly supported_xss;
+EXPORT_SYMBOL_GPL(supported_xss);
struct kvm_stats_debugfs_item debugfs_entries[] = {
{ "pf_fixed", VCPU_STAT(pf_fixed) },
@@ -2827,7 +2829,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
* IA32_XSS[bit 8]. Guests have to use RDMSR/WRMSR rather than
* XSAVES/XRSTORS to save/restore PT MSRs.
*/
- if (data != 0)
+ if (data & ~supported_xss)
return 1;
vcpu->arch.ia32_xss = data;
break;
@@ -9617,10 +9619,16 @@ int kvm_arch_hardware_setup(void)
rdmsrl_safe(MSR_EFER, &host_efer);
+ if (boot_cpu_has(X86_FEATURE_XSAVES))
+ rdmsrl(MSR_IA32_XSS, host_xss);
+
r = kvm_x86_ops->hardware_setup();
if (r != 0)
return r;
+ if (!kvm_cpu_cap_has(X86_FEATURE_XSAVES))
+ supported_xss = 0;
+
cr4_reserved_bits = kvm_host_cr4_reserved_bits(&boot_cpu_data);
if (kvm_has_tsc_control) {
@@ -9637,9 +9645,6 @@ int kvm_arch_hardware_setup(void)
kvm_default_tsc_scaling_ratio = 1ULL << kvm_tsc_scaling_ratio_frac_bits;
}
- if (boot_cpu_has(X86_FEATURE_XSAVES))
- rdmsrl(MSR_IA32_XSS, host_xss);
-
kvm_init_msr_list();
return 0;
}
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index 4d890bf..c1954e2 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -272,6 +272,7 @@ enum exit_fastpath_completion handle_fastpath_set_msr_irqoff(struct kvm_vcpu *vc
extern u64 host_xcr0;
extern u64 supported_xcr0;
+extern u64 supported_xss;
static inline bool kvm_mpx_supported(void)
{
