[PATCH 15/26] KVM: x86: Introduce cpuid_entry_{change,set,clear}() mutators

Sean Christopherson
2020-01-29T23:47:48Z

Introduce mutators to modify feature bits in CPUID entries and use the
new mutators where applicable. Using the mutators eliminates the need
to manually specify the register to modify query at no extra cost and
will allow adding runtime consistency checks on the function/index in a
future patch.

No functional change intended.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
arch/x86/kvm/cpuid.c | 62 +++++++++++++++++++-------------------------
arch/x86/kvm/cpuid.h | 31 ++++++++++++++++++++++
arch/x86/kvm/svm.c | 11 ++++----
3 files changed, 62 insertions(+), 42 deletions(-)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 99e02b468c7c..2d75410092e6 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -57,15 +57,12 @@ int kvm_update_cpuid(struct kvm_vcpu *vcpu)
return 0;

/* Update OSXSAVE bit */
- if (boot_cpu_has(X86_FEATURE_XSAVE) && best->function == 0x1) {
- best->ecx &= ~F(OSXSAVE);
- if (kvm_read_cr4_bits(vcpu, X86_CR4_OSXSAVE))
- best->ecx |= F(OSXSAVE);
- }
+ if (boot_cpu_has(X86_FEATURE_XSAVE) && best->function == 0x1)
+ cpuid_entry_change(best, X86_FEATURE_OSXSAVE,
+ kvm_read_cr4_bits(vcpu, X86_CR4_OSXSAVE));

- best->edx &= ~F(APIC);
- if (vcpu->arch.apic_base & MSR_IA32_APICBASE_ENABLE)
- best->edx |= F(APIC);
+ cpuid_entry_change(best, X86_FEATURE_APIC,
+ vcpu->arch.apic_base & MSR_IA32_APICBASE_ENABLE);

if (apic) {
if (cpuid_entry_has(best, X86_FEATURE_TSC_DEADLINE_TIMER))
@@ -75,14 +72,9 @@ int kvm_update_cpuid(struct kvm_vcpu *vcpu)
}

best = kvm_find_cpuid_entry(vcpu, 7, 0);
- if (best) {
- /* Update OSPKE bit */
- if (boot_cpu_has(X86_FEATURE_PKU) && best->function == 0x7) {
- best->ecx &= ~F(OSPKE);
- if (kvm_read_cr4_bits(vcpu, X86_CR4_PKE))
- best->ecx |= F(OSPKE);
- }
- }
+ if (best && boot_cpu_has(X86_FEATURE_PKU) && best->function == 0x7)
+ cpuid_entry_change(best, X86_FEATURE_OSPKE,
+ kvm_read_cr4_bits(vcpu, X86_CR4_PKE));

best = kvm_find_cpuid_entry(vcpu, 0xD, 0);
if (!best) {
@@ -119,12 +111,10 @@ int kvm_update_cpuid(struct kvm_vcpu *vcpu)

if (!kvm_check_has_quirk(vcpu->kvm, KVM_X86_QUIRK_MISC_ENABLE_NO_MWAIT)) {
best = kvm_find_cpuid_entry(vcpu, 0x1, 0);
- if (best) {
- if (vcpu->arch.ia32_misc_enable_msr & MSR_IA32_MISC_ENABLE_MWAIT)
- best->ecx |= F(MWAIT);
- else
- best->ecx &= ~F(MWAIT);
- }
+ if (best)
+ cpuid_entry_change(best, X86_FEATURE_MWAIT,
+ vcpu->arch.ia32_misc_enable_msr &
+ MSR_IA32_MISC_ENABLE_MWAIT);
}

/* Update physical-address width */
@@ -157,7 +147,7 @@ static void cpuid_fix_nx_cap(struct kvm_vcpu *vcpu)
}
}
if (entry && cpuid_entry_has(entry, X86_FEATURE_NX) && !is_efer_nx()) {
- entry->edx &= ~F(NX);
+ cpuid_entry_clear(entry, X86_FEATURE_NX);
printk(KERN_INFO "kvm: guest NX capability removed\n");
}
}
@@ -369,7 +359,7 @@ static inline void do_cpuid_7_mask(struct kvm_cpuid_entry2 *entry, int index)
entry->ebx &= kvm_cpuid_7_0_ebx_x86_features;
cpuid_mask(&entry->ebx, CPUID_7_0_EBX);
/* TSC_ADJUST is emulated */
- entry->ebx |= F(TSC_ADJUST);
+ cpuid_entry_set(entry, X86_FEATURE_TSC_ADJUST);

entry->ecx &= kvm_cpuid_7_0_ecx_x86_features;
f_la57 = cpuid_entry_get(entry, X86_FEATURE_LA57);
@@ -380,22 +370,22 @@ static inline void do_cpuid_7_mask(struct kvm_cpuid_entry2 *entry, int index)
entry->ecx |= f_pku;
/* PKU is not yet implemented for shadow paging. */
if (!tdp_enabled || !boot_cpu_has(X86_FEATURE_OSPKE))
- entry->ecx &= ~F(PKU);
+ cpuid_entry_clear(entry, X86_FEATURE_PKU);

entry->edx &= kvm_cpuid_7_0_edx_x86_features;
cpuid_mask(&entry->edx, CPUID_7_EDX);
if (boot_cpu_has(X86_FEATURE_IBPB) && boot_cpu_has(X86_FEATURE_IBRS))
- entry->edx |= F(SPEC_CTRL);
+ cpuid_entry_set(entry, X86_FEATURE_SPEC_CTRL);
if (boot_cpu_has(X86_FEATURE_STIBP))
- entry->edx |= F(INTEL_STIBP);
+ cpuid_entry_set(entry, X86_FEATURE_INTEL_STIBP);
if (boot_cpu_has(X86_FEATURE_SPEC_CTRL_SSBD) ||
boot_cpu_has(X86_FEATURE_AMD_SSBD))
- entry->edx |= F(SPEC_CTRL_SSBD);
+ cpuid_entry_set(entry, X86_FEATURE_SPEC_CTRL_SSBD);
/*
* We emulate ARCH_CAPABILITIES in software even
* if the host doesn't support it.
*/
- entry->edx |= F(ARCH_CAPABILITIES);
+ cpuid_entry_set(entry, X86_FEATURE_ARCH_CAPABILITIES);
break;
case 1:
entry->eax &= kvm_cpuid_7_1_eax_x86_features;
@@ -509,7 +499,7 @@ static inline int __do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 function,
cpuid_mask(&entry->ecx, CPUID_1_ECX);
/* we support x2apic emulation even if host does not support
* it since we emulate x2apic in software */
- entry->ecx |= F(X2APIC);
+ cpuid_entry_set(entry, X86_FEATURE_X2APIC);
break;
/* function 2 entries are STATEFUL. That is, repeated cpuid commands
* may return different values. This forces us to get_cpu() before
@@ -741,23 +731,23 @@ static inline int __do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 function,
* record that in cpufeatures so use them.
*/
if (boot_cpu_has(X86_FEATURE_IBPB))
- entry->ebx |= F(AMD_IBPB);
+ cpuid_entry_set(entry, X86_FEATURE_AMD_IBPB);
if (boot_cpu_has(X86_FEATURE_IBRS))
- entry->ebx |= F(AMD_IBRS);
+ cpuid_entry_set(entry, X86_FEATURE_AMD_IBRS);
if (boot_cpu_has(X86_FEATURE_STIBP))
- entry->ebx |= F(AMD_STIBP);
+ cpuid_entry_set(entry, X86_FEATURE_AMD_STIBP);
if (boot_cpu_has(X86_FEATURE_SPEC_CTRL_SSBD) ||
boot_cpu_has(X86_FEATURE_AMD_SSBD))
- entry->ebx |= F(AMD_SSBD);
+ cpuid_entry_set(entry, X86_FEATURE_AMD_SSBD);
if (!boot_cpu_has_bug(X86_BUG_SPEC_STORE_BYPASS))
- entry->ebx |= F(AMD_SSB_NO);
+ 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))
- entry->ebx |= F(VIRT_SSBD);
+ cpuid_entry_set(entry, X86_FEATURE_VIRT_SSBD);
break;
}
case 0x80000019:
diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h
index 64e96e4086e2..51f19eade5a0 100644
--- a/arch/x86/kvm/cpuid.h
+++ b/arch/x86/kvm/cpuid.h
@@ -135,6 +135,37 @@ static __always_inline bool cpuid_entry_has(struct kvm_cpuid_entry2 *entry,
return cpuid_entry_get(entry, x86_feature);
}

+static __always_inline void cpuid_entry_clear(struct kvm_cpuid_entry2 *entry,
+ unsigned x86_feature)
+{
+ u32 *reg = cpuid_entry_get_reg(entry, x86_feature);
+
+ *reg &= ~__feature_bit(x86_feature);
+}
+
+static __always_inline void cpuid_entry_set(struct kvm_cpuid_entry2 *entry,
+ unsigned x86_feature)
+{
+ int *reg = cpuid_entry_get_reg(entry, x86_feature);
+
+ *reg |= __feature_bit(x86_feature);
+}
+
+static __always_inline void cpuid_entry_change(struct kvm_cpuid_entry2 *entry,
+ unsigned x86_feature, bool set)
+{
+ int *reg = cpuid_entry_get_reg(entry, x86_feature);
+
+ /*
+ * Open coded instead of using cpuid_entry_{clear,set}() to coerce the
+ * compiler into using CMOV instead of Jcc when possible.
+ */
+ if (set)
+ *reg |= __feature_bit(x86_feature);
+ else
+ *reg &= ~__feature_bit(x86_feature);
+}
+
static __always_inline int *guest_cpuid_get_register(struct kvm_vcpu *vcpu, unsigned x86_feature)
{
struct kvm_cpuid_entry2 *entry;
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 199f491a3055..fee2af01ba21 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -6057,16 +6057,16 @@ static void svm_set_supported_cpuid(struct kvm_cpuid_entry2 *entry)
switch (entry->function) {
case 0x1:
if (avic)
- entry->ecx &= ~F(X2APIC);
+ cpuid_entry_clear(entry, X86_FEATURE_X2APIC);
break;
case 0x80000001:
if (nested)
- entry->ecx |= (1 << 2); /* Set SVM bit */
+ cpuid_entry_set(entry, X86_FEATURE_SVM);
break;
case 0x80000008:
if (boot_cpu_has(X86_FEATURE_LS_CFG_SSBD) ||
boot_cpu_has(X86_FEATURE_AMD_SSBD))
- entry->ebx |= F(VIRT_SSBD);
+ cpuid_entry_set(entry, X86_FEATURE_VIRT_SSBD);
break;
case 0x8000000A:
entry->eax = 1; /* SVM revision 1 */
@@ -6078,12 +6078,11 @@ static void svm_set_supported_cpuid(struct kvm_cpuid_entry2 *entry)

/* Support next_rip if host supports it */
if (boot_cpu_has(X86_FEATURE_NRIPS))
- entry->edx |= F(NRIPS);
+ cpuid_entry_set(entry, X86_FEATURE_NRIPS);

/* Support NPT for the guest if enabled */
if (npt_enabled)
- entry->edx |= F(NPT);
-
+ cpuid_entry_set(entry, X86_FEATURE_NPT);
}
}

--
2.24.1