[PATCH v2 51/66] KVM: x86: Set emulated/transmuted feature bits via kvm_cpu_caps

Sean Christopherson
2020-03-02T23:58:10Z

Set emulated and transmuted (set based on other features) feature bits
via kvm_cpu_caps now that the CPUID output for KVM_GET_SUPPORTED_CPUID
is direcly overidden with kvm_cpu_caps.

Note, VMX emulation of UMIP already sets kvm_cpu_caps.

No functional change intended.

Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
arch/x86/kvm/cpuid.c | 72 +++++++++++++++++++++---------------------
arch/x86/kvm/svm.c | 18 +++--------
arch/x86/kvm/vmx/vmx.c | 18 +----------
3 files changed, 42 insertions(+), 66 deletions(-)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 5fef02dbf4e1..c0ee0cb33a37 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -315,6 +315,8 @@ void kvm_set_cpu_caps(void)
0 /* Reserved*/ | F(AES) | F(XSAVE) | 0 /* OSXSAVE */ | F(AVX) |
F(F16C) | F(RDRAND)
);
+ /* KVM emulates x2apic in software irrespective of host support. */
+ kvm_cpu_cap_set(X86_FEATURE_X2APIC);

kvm_cpu_cap_mask(CPUID_1_EDX,
F(FPU) | F(VME) | F(DE) | F(PSE) |
@@ -351,6 +353,17 @@ void kvm_set_cpu_caps(void)
F(MD_CLEAR)
);

+ /* TSC_ADJUST and ARCH_CAPABILITIES are emulated in software. */
+ kvm_cpu_cap_set(X86_FEATURE_TSC_ADJUST);
+ kvm_cpu_cap_set(X86_FEATURE_ARCH_CAPABILITIES);
+
+ if (boot_cpu_has(X86_FEATURE_IBPB) && boot_cpu_has(X86_FEATURE_IBRS))
+ kvm_cpu_cap_set(X86_FEATURE_SPEC_CTRL);
+ if (boot_cpu_has(X86_FEATURE_STIBP))
+ kvm_cpu_cap_set(X86_FEATURE_INTEL_STIBP);
+ if (boot_cpu_has(X86_FEATURE_AMD_SSBD))
+ kvm_cpu_cap_set(X86_FEATURE_SPEC_CTRL_SSBD);
+
kvm_cpu_cap_mask(CPUID_7_1_EAX,
F(AVX512_BF16)
);
@@ -384,6 +397,29 @@ void kvm_set_cpu_caps(void)
F(AMD_SSB_NO) | F(AMD_STIBP) | F(AMD_STIBP_ALWAYS_ON)
);

+ /*
+ * AMD has separate bits for each SPEC_CTRL bit.
+ * arch/x86/kernel/cpu/bugs.c is kind enough to
+ * record that in cpufeatures so use them.
+ */
+ if (boot_cpu_has(X86_FEATURE_IBPB))
+ kvm_cpu_cap_set(X86_FEATURE_AMD_IBPB);
+ if (boot_cpu_has(X86_FEATURE_IBRS))
+ kvm_cpu_cap_set(X86_FEATURE_AMD_IBRS);
+ if (boot_cpu_has(X86_FEATURE_STIBP))
+ kvm_cpu_cap_set(X86_FEATURE_AMD_STIBP);
+ if (boot_cpu_has(X86_FEATURE_SPEC_CTRL_SSBD))
+ kvm_cpu_cap_set(X86_FEATURE_AMD_SSBD);
+ if (!boot_cpu_has_bug(X86_BUG_SPEC_STORE_BYPASS))
+ kvm_cpu_cap_set(X86_FEATURE_AMD_SSB_NO);
+ /*
+ * The preference is to use SPEC CTRL MSR instead of the
+ * VIRT_SPEC MSR.
+ */
+ if (boot_cpu_has(X86_FEATURE_LS_CFG_SSBD) &&
+ !boot_cpu_has(X86_FEATURE_AMD_SSBD))
+ kvm_cpu_cap_set(X86_FEATURE_VIRT_SSBD);
+
/*
* Hide all SVM features by default, SVM will set the cap bits for
* features it emulates and/or exposes for L1.
@@ -492,9 +528,6 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
case 1:
cpuid_entry_override(entry, CPUID_1_EDX);
cpuid_entry_override(entry, CPUID_1_ECX);
- /* we support x2apic emulation even if host does not support
- * it since we emulate x2apic in software */
- cpuid_entry_set(entry, X86_FEATURE_X2APIC);
break;
case 2:
/*
@@ -540,17 +573,6 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
cpuid_entry_override(entry, CPUID_7_ECX);
cpuid_entry_override(entry, CPUID_7_EDX);

- /* TSC_ADJUST and ARCH_CAPABILITIES are emulated in software. */
- cpuid_entry_set(entry, X86_FEATURE_TSC_ADJUST);
- cpuid_entry_set(entry, X86_FEATURE_ARCH_CAPABILITIES);
-
- if (boot_cpu_has(X86_FEATURE_IBPB) && boot_cpu_has(X86_FEATURE_IBRS))
- cpuid_entry_set(entry, X86_FEATURE_SPEC_CTRL);
- if (boot_cpu_has(X86_FEATURE_STIBP))
- cpuid_entry_set(entry, X86_FEATURE_INTEL_STIBP);
- if (boot_cpu_has(X86_FEATURE_AMD_SSBD))
- cpuid_entry_set(entry, X86_FEATURE_SPEC_CTRL_SSBD);
-
/* KVM only supports 0x7.0 and 0x7.1, capped above via min(). */
if (entry->eax == 1) {
entry = do_host_cpuid(array, function, 1);
@@ -722,28 +744,6 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
entry->eax = g_phys_as | (virt_as << 8);
entry->edx = 0;
cpuid_entry_override(entry, CPUID_8000_0008_EBX);
- /*
- * AMD has separate bits for each SPEC_CTRL bit.
- * arch/x86/kernel/cpu/bugs.c is kind enough to
- * record that in cpufeatures so use them.
- */
- if (boot_cpu_has(X86_FEATURE_IBPB))
- cpuid_entry_set(entry, X86_FEATURE_AMD_IBPB);
- if (boot_cpu_has(X86_FEATURE_IBRS))
- cpuid_entry_set(entry, X86_FEATURE_AMD_IBRS);
- if (boot_cpu_has(X86_FEATURE_STIBP))
- cpuid_entry_set(entry, X86_FEATURE_AMD_STIBP);
- if (boot_cpu_has(X86_FEATURE_SPEC_CTRL_SSBD))
- cpuid_entry_set(entry, X86_FEATURE_AMD_SSBD);
- if (!boot_cpu_has_bug(X86_BUG_SPEC_STORE_BYPASS))
- cpuid_entry_set(entry, X86_FEATURE_AMD_SSB_NO);
- /*
- * The preference is to use SPEC CTRL MSR instead of the
- * VIRT_SPEC MSR.
- */
- if (boot_cpu_has(X86_FEATURE_LS_CFG_SSBD) &&
- !boot_cpu_has(X86_FEATURE_AMD_SSBD))
- cpuid_entry_set(entry, X86_FEATURE_VIRT_SSBD);
break;
}
case 0x80000019:
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 964331106e9a..d351007eb7f9 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1377,6 +1377,11 @@ static __init void svm_set_cpu_caps(void)
if (nested)
kvm_cpu_cap_set(X86_FEATURE_SVM);

+ /* CPUID 0x80000008 */
+ if (boot_cpu_has(X86_FEATURE_LS_CFG_SSBD) ||
+ boot_cpu_has(X86_FEATURE_AMD_SSBD))
+ kvm_cpu_cap_set(X86_FEATURE_VIRT_SSBD);
+
/* CPUID 0x8000000A */
/* Support next_rip if host supports it */
kvm_cpu_cap_check_and_set(X86_FEATURE_NRIPS);
@@ -6047,22 +6052,9 @@ static void svm_cpuid_update(struct kvm_vcpu *vcpu)
APICV_INHIBIT_REASON_NESTED);
}

-/*
- * Vendor specific emulation must be handled via ->set_supported_cpuid(), not
- * svm_set_cpu_caps(), as capabilities configured during hardware_setup() are
- * masked against hardware/kernel support, i.e. they'd be lost.
- *
- * Note, setting a flag based on a *different* feature, e.g. setting VIRT_SSBD
- * if LS_CFG_SSBD or AMD_SSBD is supported, is effectively emulation.
- */
static void svm_set_supported_cpuid(struct kvm_cpuid_entry2 *entry)
{
switch (entry->function) {
- case 0x80000008:
- if (boot_cpu_has(X86_FEATURE_LS_CFG_SSBD) ||
- boot_cpu_has(X86_FEATURE_AMD_SSBD))
- cpuid_entry_set(entry, X86_FEATURE_VIRT_SSBD);
- break;
case 0x8000000A:
entry->eax = 1; /* SVM revision 1 */
entry->ebx = 8; /* Lets support 8 ASIDs in case we add proper
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index be2aecda733b..d5a5e8f987c8 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -7119,25 +7119,9 @@ static void vmx_cpuid_update(struct kvm_vcpu *vcpu)
}
}

-/*
- * Vendor specific emulation must be handled via ->set_supported_cpuid(), not
- * vmx_set_cpu_caps(), as capabilities configured during hardware_setup() are
- * masked against hardware/kernel support, i.e. they'd be lost.
- */
static void vmx_set_supported_cpuid(struct kvm_cpuid_entry2 *entry)
{
- switch (entry->function) {
- case 0x7:
- /*
- * UMIP needs to be manually set even though vmx_set_cpu_caps()
- * also sets UMIP since do_host_cpuid() will drop it.
- */
- if (vmx_umip_emulated())
- cpuid_entry_set(entry, X86_FEATURE_UMIP);
- break;
- default:
- break;
- }
+
}

static __init void vmx_set_cpu_caps(void)
--
2.24.1