[PATCH v2 0/5] KVM: x86: X86_FEATURE bit() cleanup

[PATCH v2 0/5] KVM: x86: X86_FEATURE bit() cleanup

[Sean Christopherson]

Small series to add build-time protections on reverse CPUID lookup (and
other usages of bit()), and to rename the misleading-generic bit() helper
to something that better conveys its purpose.

I don't love emulator changes in patch 1 as adding one-off helpers is a
bit silly, but IMO it's the lesser of two evils, e.g. adding dedicated
helpers is arguably less error prone than manually encoding a CPUID
lookup, and the helpers approach avoids having to include cpuid.h in the
emulator code.

v2:
  - Rework the assertions to use the reverse_cpuid table instead of
    using the last cpufeatures word (which was not at all intuitive).

Sean Christopherson (5):
  KVM: x86: Add dedicated emulator helpers for querying CPUID features
  KVM: x86: Move bit() helper to cpuid.h
  KVM: x86: Add CPUID_7_1_EAX to the reverse CPUID table
  KVM: x86: Expand build-time assertion on reverse CPUID usage
  KVM: x86: Refactor and rename bit() to feature_bit() macro

 arch/x86/include/asm/kvm_emulate.h |  4 +++
 arch/x86/kvm/cpuid.c               |  5 ++--
 arch/x86/kvm/cpuid.h               | 41 +++++++++++++++++++++++++----
 arch/x86/kvm/emulate.c             | 21 +++------------
 arch/x86/kvm/svm.c                 |  4 +--
 arch/x86/kvm/vmx/vmx.c             | 42 +++++++++++++++---------------
 arch/x86/kvm/x86.c                 | 18 +++++++++++++
 arch/x86/kvm/x86.h                 |  5 ----
 8 files changed, 87 insertions(+), 53 deletions(-)

-- 
2.24.1

[PATCH v2 1/5] KVM: x86: Add dedicated emulator helpers for querying CPUID features

[Sean Christopherson]

Add feature-specific helpers for querying guest CPUID support from the
emulator instead of having the emulator do a full CPUID and perform its
own bit tests.  The primary motivation is to eliminate the emulator's
usage of bit() so that future patches can add more extensive build-time
assertions on the usage of bit() without having to expose yet more code
to the emulator.

Note, providing a generic guest_cpuid_has() to the emulator doesn't work
due to the existing built-time assertions in guest_cpuid_has(), which
require the feature being checked to be a compile-time constant.

No functional change intended.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
 arch/x86/include/asm/kvm_emulate.h |  4 ++++
 arch/x86/kvm/emulate.c             | 21 +++------------------
 arch/x86/kvm/x86.c                 | 18 ++++++++++++++++++
 3 files changed, 25 insertions(+), 18 deletions(-)

diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h
index 77cf6c11f66b..03946eb3e2b9 100644
--- a/arch/x86/include/asm/kvm_emulate.h
+++ b/arch/x86/include/asm/kvm_emulate.h
@@ -222,6 +222,10 @@ struct x86_emulate_ops {
 
 	bool (*get_cpuid)(struct x86_emulate_ctxt *ctxt, u32 *eax, u32 *ebx,
 			  u32 *ecx, u32 *edx, bool check_limit);
+	bool (*guest_has_long_mode)(struct x86_emulate_ctxt *ctxt);
+	bool (*guest_has_movbe)(struct x86_emulate_ctxt *ctxt);
+	bool (*guest_has_fxsr)(struct x86_emulate_ctxt *ctxt);
+
 	void (*set_nmi_mask)(struct x86_emulate_ctxt *ctxt, bool masked);
 
 	unsigned (*get_hflags)(struct x86_emulate_ctxt *ctxt);
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 952d1a4f4d7e..e9833e345a5c 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -2348,12 +2348,7 @@ static int em_lseg(struct x86_emulate_ctxt *ctxt)
 static int emulator_has_longmode(struct x86_emulate_ctxt *ctxt)
 {
 #ifdef CONFIG_X86_64
-	u32 eax, ebx, ecx, edx;
-
-	eax = 0x80000001;
-	ecx = 0;
-	ctxt->ops->get_cpuid(ctxt, &eax, &ebx, &ecx, &edx, false);
-	return edx & bit(X86_FEATURE_LM);
+	return ctxt->ops->guest_has_long_mode(ctxt);
 #else
 	return false;
 #endif
@@ -3618,18 +3613,11 @@ static int em_mov(struct x86_emulate_ctxt *ctxt)
 	return X86EMUL_CONTINUE;
 }
 
-#define FFL(x) bit(X86_FEATURE_##x)
-
 static int em_movbe(struct x86_emulate_ctxt *ctxt)
 {
-	u32 ebx, ecx, edx, eax = 1;
 	u16 tmp;
 
-	/*
-	 * Check MOVBE is set in the guest-visible CPUID leaf.
-	 */
-	ctxt->ops->get_cpuid(ctxt, &eax, &ebx, &ecx, &edx, false);
-	if (!(ecx & FFL(MOVBE)))
+	if (!ctxt->ops->guest_has_movbe(ctxt))
 		return emulate_ud(ctxt);
 
 	switch (ctxt->op_bytes) {
@@ -4027,10 +4015,7 @@ static int em_movsxd(struct x86_emulate_ctxt *ctxt)
 
 static int check_fxsr(struct x86_emulate_ctxt *ctxt)
 {
-	u32 eax = 1, ebx, ecx = 0, edx;
-
-	ctxt->ops->get_cpuid(ctxt, &eax, &ebx, &ecx, &edx, false);
-	if (!(edx & FFL(FXSR)))
+	if (!ctxt->ops->guest_has_fxsr(ctxt))
 		return emulate_ud(ctxt);
 
 	if (ctxt->ops->get_cr(ctxt, 0) & (X86_CR0_TS | X86_CR0_EM))
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 8bb2fb1705ff..6bca14071d30 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6184,6 +6184,21 @@ static bool emulator_get_cpuid(struct x86_emulate_ctxt *ctxt,
 	return kvm_cpuid(emul_to_vcpu(ctxt), eax, ebx, ecx, edx, check_limit);
 }
 
+static bool emulator_guest_has_long_mode(struct x86_emulate_ctxt *ctxt)
+{
+	return guest_cpuid_has(emul_to_vcpu(ctxt), X86_FEATURE_LM);
+}
+
+static bool emulator_guest_has_movbe(struct x86_emulate_ctxt *ctxt)
+{
+	return guest_cpuid_has(emul_to_vcpu(ctxt), X86_FEATURE_MOVBE);
+}
+
+static bool emulator_guest_has_fxsr(struct x86_emulate_ctxt *ctxt)
+{
+	return guest_cpuid_has(emul_to_vcpu(ctxt), X86_FEATURE_FXSR);
+}
+
 static ulong emulator_read_gpr(struct x86_emulate_ctxt *ctxt, unsigned reg)
 {
 	return kvm_register_read(emul_to_vcpu(ctxt), reg);
@@ -6261,6 +6276,9 @@ static const struct x86_emulate_ops emulate_ops = {
 	.fix_hypercall       = emulator_fix_hypercall,
 	.intercept           = emulator_intercept,
 	.get_cpuid           = emulator_get_cpuid,
+	.guest_has_long_mode = emulator_guest_has_long_mode,
+	.guest_has_movbe     = emulator_guest_has_movbe,
+	.guest_has_fxsr      = emulator_guest_has_fxsr,
 	.set_nmi_mask        = emulator_set_nmi_mask,
 	.get_hflags          = emulator_get_hflags,
 	.set_hflags          = emulator_set_hflags,
-- 
2.24.1

[PATCH v2 2/5] KVM: x86: Move bit() helper to cpuid.h

[Sean Christopherson]

Move bit() to cpuid.h in preparation for incorporating the reverse_cpuid
array in bit() build-time assertions.  Opportunistically use the BIT()
macro instead of open-coding the shift.

No functional change intended.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
 arch/x86/kvm/cpuid.h | 5 +++++
 arch/x86/kvm/x86.h   | 5 -----
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h
index d78a61408243..a631329ebec7 100644
--- a/arch/x86/kvm/cpuid.h
+++ b/arch/x86/kvm/cpuid.h
@@ -55,6 +55,11 @@ static const struct cpuid_reg reverse_cpuid[] = {
 	[CPUID_7_EDX]         = {         7, 0, CPUID_EDX},
 };
 
+static inline u32 bit(int bitno)
+{
+	return BIT(bitno & 31);
+}
+
 static __always_inline struct cpuid_reg x86_feature_cpuid(unsigned x86_feature)
 {
 	unsigned x86_leaf = x86_feature / 32;
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index cab5e71f0f0f..5f6b8f9a385c 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -144,11 +144,6 @@ static inline bool is_pae_paging(struct kvm_vcpu *vcpu)
 	return !is_long_mode(vcpu) && is_pae(vcpu) && is_paging(vcpu);
 }
 
-static inline u32 bit(int bitno)
-{
-	return 1 << (bitno & 31);
-}
-
 static inline u8 vcpu_virt_addr_bits(struct kvm_vcpu *vcpu)
 {
 	return kvm_read_cr4_bits(vcpu, X86_CR4_LA57) ? 57 : 48;
-- 
2.24.1

[PATCH v2 3/5] KVM: x86: Add CPUID_7_1_EAX to the reverse CPUID table

[Sean Christopherson]

Add an entry for CPUID_7_1_EAX in the reserve_cpuid array in preparation
for incorporating the array in bit() build-time assertions, specifically
to avoid an assertion on F(AVX512_BF16) in do_cpuid_7_mask().

No functional change intended.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
 arch/x86/kvm/cpuid.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h
index a631329ebec7..8c77d829e27d 100644
--- a/arch/x86/kvm/cpuid.h
+++ b/arch/x86/kvm/cpuid.h
@@ -53,6 +53,7 @@ static const struct cpuid_reg reverse_cpuid[] = {
 	[CPUID_7_ECX]         = {         7, 0, CPUID_ECX},
 	[CPUID_8000_0007_EBX] = {0x80000007, 0, CPUID_EBX},
 	[CPUID_7_EDX]         = {         7, 0, CPUID_EDX},
+	[CPUID_7_1_EAX]       = {         7, 1, CPUID_EAX},
 };
 
 static inline u32 bit(int bitno)
-- 
2.24.1

[PATCH v2 4/5] KVM: x86: Expand build-time assertion on reverse CPUID usage

[Sean Christopherson]

Add build-time checks to ensure KVM isn't trying to do a reverse CPUID
lookup on Linux-defined feature bits, along with comments to explain
the gory details of X86_FEATUREs and bit().

No functional change intended.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
 arch/x86/kvm/cpuid.c |  3 ++-
 arch/x86/kvm/cpuid.h | 39 +++++++++++++++++++++++++++++++--------
 2 files changed, 33 insertions(+), 9 deletions(-)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index cfafa320a8cf..a3b41e87e810 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -281,8 +281,9 @@ int kvm_vcpu_ioctl_get_cpuid2(struct kvm_vcpu *vcpu,
 	return r;
 }
 
-static void cpuid_mask(u32 *word, int wordnum)
+static __always_inline void cpuid_mask(u32 *word, int wordnum)
 {
+	reverse_cpuid_check(wordnum);
 	*word &= boot_cpu_data.x86_capability[wordnum];
 }
 
diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h
index 8c77d829e27d..fc5a4cde260b 100644
--- a/arch/x86/kvm/cpuid.h
+++ b/arch/x86/kvm/cpuid.h
@@ -56,18 +56,41 @@ static const struct cpuid_reg reverse_cpuid[] = {
 	[CPUID_7_1_EAX]       = {         7, 1, CPUID_EAX},
 };
 
-static inline u32 bit(int bitno)
+/*
+ * Reverse CPUID and its derivatives can only be used for hardware-defined
+ * feature words, i.e. words whose bits directly correspond to a CPUID leaf.
+ * Retrieving a feature bit or masking guest CPUID from a Linux-defined word
+ * is nonsensical as the bit number/mask is an arbitrary software-defined value
+ * and can't be used by KVM to query/control guest capabilities.  And obviously
+ * the leaf being queried must have an entry in the lookup table.
+ */
+static __always_inline void reverse_cpuid_check(unsigned x86_leaf)
 {
-	return BIT(bitno & 31);
-}
-
-static __always_inline struct cpuid_reg x86_feature_cpuid(unsigned x86_feature)
-{
-	unsigned x86_leaf = x86_feature / 32;
-
+	BUILD_BUG_ON(x86_leaf == CPUID_LNX_1);
+	BUILD_BUG_ON(x86_leaf == CPUID_LNX_2);
+	BUILD_BUG_ON(x86_leaf == CPUID_LNX_3);
+	BUILD_BUG_ON(x86_leaf == CPUID_LNX_4);
 	BUILD_BUG_ON(x86_leaf >= ARRAY_SIZE(reverse_cpuid));
 	BUILD_BUG_ON(reverse_cpuid[x86_leaf].function == 0);
+}
 
+/*
+ * Retrieve the bit mask from an X86_FEATURE_* definition.  Features contain
+ * the hardware defined bit number (stored in bits 4:0) and a software defined
+ * "word" (stored in bits 31:5).  The word is used to index into arrays of
+ * bit masks that hold the per-cpu feature capabilities, e.g. this_cpu_has().
+ */
+static __always_inline u32 bit(int x86_feature)
+{
+	reverse_cpuid_check(x86_feature / 32);
+	return 1 << (x86_feature & 31);
+}
+
+static __always_inline struct cpuid_reg x86_feature_cpuid(unsigned x86_feature)
+{
+	unsigned x86_leaf = x86_feature / 32;
+
+	reverse_cpuid_check(x86_leaf);
 	return reverse_cpuid[x86_leaf];
 }
 
-- 
2.24.1

[PATCH v2 5/5] KVM: x86: Refactor and rename bit() to feature_bit() macro

[Sean Christopherson]

Rename bit() to __feature_bit() to give it a more descriptive name, and
add a macro, feature_bit(), to stuff the X68_FEATURE_ prefix to keep
line lengths manageable for code that hardcodes the bit to be retrieved.

No functional change intended.

Cc: Jim Mattson <jmattson@google.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
 arch/x86/kvm/cpuid.c   |  2 +-
 arch/x86/kvm/cpuid.h   |  8 +++++---
 arch/x86/kvm/svm.c     |  4 ++--
 arch/x86/kvm/vmx/vmx.c | 42 +++++++++++++++++++++---------------------
 4 files changed, 29 insertions(+), 27 deletions(-)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index a3b41e87e810..390dff4beb07 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -62,7 +62,7 @@ u64 kvm_supported_xcr0(void)
 	return xcr0;
 }
 
-#define F(x) bit(X86_FEATURE_##x)
+#define F feature_bit
 
 int kvm_update_cpuid(struct kvm_vcpu *vcpu)
 {
diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h
index fc5a4cde260b..5d0bede5fc80 100644
--- a/arch/x86/kvm/cpuid.h
+++ b/arch/x86/kvm/cpuid.h
@@ -80,12 +80,14 @@ static __always_inline void reverse_cpuid_check(unsigned x86_leaf)
  * "word" (stored in bits 31:5).  The word is used to index into arrays of
  * bit masks that hold the per-cpu feature capabilities, e.g. this_cpu_has().
  */
-static __always_inline u32 bit(int x86_feature)
+static __always_inline u32 __feature_bit(int x86_feature)
 {
 	reverse_cpuid_check(x86_feature / 32);
 	return 1 << (x86_feature & 31);
 }
 
+#define feature_bit(name)  __feature_bit(X86_FEATURE_##name)
+
 static __always_inline struct cpuid_reg x86_feature_cpuid(unsigned x86_feature)
 {
 	unsigned x86_leaf = x86_feature / 32;
@@ -130,7 +132,7 @@ static __always_inline bool guest_cpuid_has(struct kvm_vcpu *vcpu, unsigned x86_
 	if (!reg)
 		return false;
 
-	return *reg & bit(x86_feature);
+	return *reg & __feature_bit(x86_feature);
 }
 
 static __always_inline void guest_cpuid_clear(struct kvm_vcpu *vcpu, unsigned x86_feature)
@@ -139,7 +141,7 @@ static __always_inline void guest_cpuid_clear(struct kvm_vcpu *vcpu, unsigned x8
 
 	reg = guest_cpuid_get_register(vcpu, x86_feature);
 	if (reg)
-		*reg &= ~bit(x86_feature);
+		*reg &= ~__feature_bit(x86_feature);
 }
 
 static inline bool guest_cpuid_is_amd(struct kvm_vcpu *vcpu)
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 8f1b715dfde8..832b8ad5a178 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -5924,14 +5924,14 @@ static void svm_cpuid_update(struct kvm_vcpu *vcpu)
 	guest_cpuid_clear(vcpu, X86_FEATURE_X2APIC);
 }
 
-#define F(x) bit(X86_FEATURE_##x)
+#define F feature_bit
 
 static void svm_set_supported_cpuid(u32 func, struct kvm_cpuid_entry2 *entry)
 {
 	switch (func) {
 	case 0x1:
 		if (avic)
-			entry->ecx &= ~bit(X86_FEATURE_X2APIC);
+			entry->ecx &= ~F(X2APIC);
 		break;
 	case 0x80000001:
 		if (nested)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 51e3b27f90ed..3608de5649f2 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -6979,28 +6979,28 @@ static void nested_vmx_cr_fixed1_bits_update(struct kvm_vcpu *vcpu)
 } while (0)
 
 	entry = kvm_find_cpuid_entry(vcpu, 0x1, 0);
-	cr4_fixed1_update(X86_CR4_VME,        edx, bit(X86_FEATURE_VME));
-	cr4_fixed1_update(X86_CR4_PVI,        edx, bit(X86_FEATURE_VME));
-	cr4_fixed1_update(X86_CR4_TSD,        edx, bit(X86_FEATURE_TSC));
-	cr4_fixed1_update(X86_CR4_DE,         edx, bit(X86_FEATURE_DE));
-	cr4_fixed1_update(X86_CR4_PSE,        edx, bit(X86_FEATURE_PSE));
-	cr4_fixed1_update(X86_CR4_PAE,        edx, bit(X86_FEATURE_PAE));
-	cr4_fixed1_update(X86_CR4_MCE,        edx, bit(X86_FEATURE_MCE));
-	cr4_fixed1_update(X86_CR4_PGE,        edx, bit(X86_FEATURE_PGE));
-	cr4_fixed1_update(X86_CR4_OSFXSR,     edx, bit(X86_FEATURE_FXSR));
-	cr4_fixed1_update(X86_CR4_OSXMMEXCPT, edx, bit(X86_FEATURE_XMM));
-	cr4_fixed1_update(X86_CR4_VMXE,       ecx, bit(X86_FEATURE_VMX));
-	cr4_fixed1_update(X86_CR4_SMXE,       ecx, bit(X86_FEATURE_SMX));
-	cr4_fixed1_update(X86_CR4_PCIDE,      ecx, bit(X86_FEATURE_PCID));
-	cr4_fixed1_update(X86_CR4_OSXSAVE,    ecx, bit(X86_FEATURE_XSAVE));
+	cr4_fixed1_update(X86_CR4_VME,        edx, feature_bit(VME));
+	cr4_fixed1_update(X86_CR4_PVI,        edx, feature_bit(VME));
+	cr4_fixed1_update(X86_CR4_TSD,        edx, feature_bit(TSC));
+	cr4_fixed1_update(X86_CR4_DE,         edx, feature_bit(DE));
+	cr4_fixed1_update(X86_CR4_PSE,        edx, feature_bit(PSE));
+	cr4_fixed1_update(X86_CR4_PAE,        edx, feature_bit(PAE));
+	cr4_fixed1_update(X86_CR4_MCE,        edx, feature_bit(MCE));
+	cr4_fixed1_update(X86_CR4_PGE,        edx, feature_bit(PGE));
+	cr4_fixed1_update(X86_CR4_OSFXSR,     edx, feature_bit(FXSR));
+	cr4_fixed1_update(X86_CR4_OSXMMEXCPT, edx, feature_bit(XMM));
+	cr4_fixed1_update(X86_CR4_VMXE,       ecx, feature_bit(VMX));
+	cr4_fixed1_update(X86_CR4_SMXE,       ecx, feature_bit(SMX));
+	cr4_fixed1_update(X86_CR4_PCIDE,      ecx, feature_bit(PCID));
+	cr4_fixed1_update(X86_CR4_OSXSAVE,    ecx, feature_bit(XSAVE));
 
 	entry = kvm_find_cpuid_entry(vcpu, 0x7, 0);
-	cr4_fixed1_update(X86_CR4_FSGSBASE,   ebx, bit(X86_FEATURE_FSGSBASE));
-	cr4_fixed1_update(X86_CR4_SMEP,       ebx, bit(X86_FEATURE_SMEP));
-	cr4_fixed1_update(X86_CR4_SMAP,       ebx, bit(X86_FEATURE_SMAP));
-	cr4_fixed1_update(X86_CR4_PKE,        ecx, bit(X86_FEATURE_PKU));
-	cr4_fixed1_update(X86_CR4_UMIP,       ecx, bit(X86_FEATURE_UMIP));
-	cr4_fixed1_update(X86_CR4_LA57,       ecx, bit(X86_FEATURE_LA57));
+	cr4_fixed1_update(X86_CR4_FSGSBASE,   ebx, feature_bit(FSGSBASE));
+	cr4_fixed1_update(X86_CR4_SMEP,       ebx, feature_bit(SMEP));
+	cr4_fixed1_update(X86_CR4_SMAP,       ebx, feature_bit(SMAP));
+	cr4_fixed1_update(X86_CR4_PKE,        ecx, feature_bit(PKU));
+	cr4_fixed1_update(X86_CR4_UMIP,       ecx, feature_bit(UMIP));
+	cr4_fixed1_update(X86_CR4_LA57,       ecx, feature_bit(LA57));
 
 #undef cr4_fixed1_update
 }
@@ -7134,7 +7134,7 @@ static void vmx_cpuid_update(struct kvm_vcpu *vcpu)
 static void vmx_set_supported_cpuid(u32 func, struct kvm_cpuid_entry2 *entry)
 {
 	if (func == 1 && nested)
-		entry->ecx |= bit(X86_FEATURE_VMX);
+		entry->ecx |= feature_bit(VMX);
 }
 
 static void vmx_request_immediate_exit(struct kvm_vcpu *vcpu)
-- 
2.24.1

Re: [PATCH v2 0/5] KVM: x86: X86_FEATURE bit() cleanup

[Paolo Bonzini]

On 17/12/19 22:32, Sean Christopherson wrote:
> Small series to add build-time protections on reverse CPUID lookup (and
> other usages of bit()), and to rename the misleading-generic bit() helper
> to something that better conveys its purpose.
> 
> I don't love emulator changes in patch 1 as adding one-off helpers is a
> bit silly, but IMO it's the lesser of two evils, e.g. adding dedicated
> helpers is arguably less error prone than manually encoding a CPUID
> lookup, and the helpers approach avoids having to include cpuid.h in the
> emulator code.
> 
> v2:
>   - Rework the assertions to use the reverse_cpuid table instead of
>     using the last cpufeatures word (which was not at all intuitive).
> 
> Sean Christopherson (5):
>   KVM: x86: Add dedicated emulator helpers for querying CPUID features
>   KVM: x86: Move bit() helper to cpuid.h
>   KVM: x86: Add CPUID_7_1_EAX to the reverse CPUID table
>   KVM: x86: Expand build-time assertion on reverse CPUID usage
>   KVM: x86: Refactor and rename bit() to feature_bit() macro
> 
>  arch/x86/include/asm/kvm_emulate.h |  4 +++
>  arch/x86/kvm/cpuid.c               |  5 ++--
>  arch/x86/kvm/cpuid.h               | 41 +++++++++++++++++++++++++----
>  arch/x86/kvm/emulate.c             | 21 +++------------
>  arch/x86/kvm/svm.c                 |  4 +--
>  arch/x86/kvm/vmx/vmx.c             | 42 +++++++++++++++---------------
>  arch/x86/kvm/x86.c                 | 18 +++++++++++++
>  arch/x86/kvm/x86.h                 |  5 ----
>  8 files changed, 87 insertions(+), 53 deletions(-)
> 

Queued, thanks.

Paolo