[PATCH v5 2/8] KVM: x86: Implement CET CPUID support for Guest

[Yang Weijiang]

CET SHSTK and IBT features are introduced here so that
CPUID.(EAX=7, ECX=0):ECX[bit 7] and EDX[bit 20] reflect them.
CET xsave components for supervisor and user mode are reported
via CPUID.(EAX=0xD, ECX=1):ECX[bit 11] and ECX[bit 12]
respectively.

To make the code look clean, wrap CPUID(0xD,n>=1) report code in
a helper function now.

Signed-off-by: Yang Weijiang <weijiang.yang@xxxxxxxxx>
Co-developed-by: Zhang Yi Z <yi.z.zhang@xxxxxxxxxxxxxxx>
---
 arch/x86/include/asm/kvm_host.h |  4 +-
 arch/x86/kvm/cpuid.c            | 97 +++++++++++++++++++++------------
 arch/x86/kvm/vmx/vmx.c          |  6 ++
 arch/x86/kvm/x86.h              |  4 ++
 4 files changed, 76 insertions(+), 35 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index a5db4475e72d..8c3f0ddc7676 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -91,7 +91,8 @@
 			  | X86_CR4_PGE | X86_CR4_PCE | X86_CR4_OSFXSR | X86_CR4_PCIDE \
 			  | X86_CR4_OSXSAVE | X86_CR4_SMEP | X86_CR4_FSGSBASE \
 			  | X86_CR4_OSXMMEXCPT | X86_CR4_LA57 | X86_CR4_VMXE \
-			  | X86_CR4_SMAP | X86_CR4_PKE | X86_CR4_UMIP))
+			  | X86_CR4_SMAP | X86_CR4_PKE | X86_CR4_UMIP \
+			  | X86_CR4_CET))
 
 #define CR8_RESERVED_BITS (~(unsigned long)X86_CR8_TPR)
 
@@ -1192,6 +1193,7 @@ struct kvm_x86_ops {
 	int (*nested_enable_evmcs)(struct kvm_vcpu *vcpu,
 				   uint16_t *vmcs_version);
 	uint16_t (*nested_get_evmcs_version)(struct kvm_vcpu *vcpu);
+	u64 (*supported_xss)(void);
 };
 
 struct kvm_arch_async_pf {
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index fd3951638ae4..b9fc967fe55a 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -65,6 +65,11 @@ u64 kvm_supported_xcr0(void)
 	return xcr0;
 }
 
+u64 kvm_supported_xss(void)
+{
+	return KVM_SUPPORTED_XSS & kvm_x86_ops->supported_xss();
+}
+
 #define F(x) bit(X86_FEATURE_##x)
 
 int kvm_update_cpuid(struct kvm_vcpu *vcpu)
@@ -316,6 +321,50 @@ static int __do_cpuid_ent_emulated(struct kvm_cpuid_entry2 *entry,
 	return 0;
 }
 
+static inline int __do_cpuid_dx_leaf(struct kvm_cpuid_entry2 *entry, int *nent,
+				     int maxnent, u64 xss_mask, u64 xcr0_mask,
+				     u32 eax_mask)
+{
+	int idx, i;
+	u64 mask;
+	u64 supported;
+
+	for (idx = 1, i = 1; idx < 64; ++idx) {
+		mask = ((u64)1 << idx);
+		if (*nent >= maxnent)
+			return -EINVAL;
+
+		do_cpuid_1_ent(&entry[i], 0xD, idx);
+		if (idx == 1) {
+			entry[i].eax &= eax_mask;
+			cpuid_mask(&entry[i].eax, CPUID_D_1_EAX);
+			supported = xcr0_mask | xss_mask;
+			entry[i].ebx = 0;
+			entry[i].edx = 0;
+			entry[i].ecx &= xss_mask;
+			if (entry[i].eax & (F(XSAVES) | F(XSAVEC))) {
+				entry[i].ebx =
+					xstate_required_size(supported,
+							     true);
+			}
+		} else {
+			supported = (entry[i].ecx & 1) ? xss_mask :
+				     xcr0_mask;
+			if (entry[i].eax == 0 || !(supported & mask))
+				continue;
+			entry[i].ecx &= 1;
+			entry[i].edx = 0;
+			if (entry[i].ecx)
+				entry[i].ebx = 0;
+		}
+		entry[i].flags |=
+			KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
+		++*nent;
+		++i;
+	}
+	return 0;
+}
+
 static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
 				 u32 index, int *nent, int maxnent)
 {
@@ -405,12 +454,13 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
 		F(AVX512VBMI) | F(LA57) | F(PKU) | 0 /*OSPKE*/ |
 		F(AVX512_VPOPCNTDQ) | F(UMIP) | F(AVX512_VBMI2) | F(GFNI) |
 		F(VAES) | F(VPCLMULQDQ) | F(AVX512_VNNI) | F(AVX512_BITALG) |
-		F(CLDEMOTE) | F(MOVDIRI) | F(MOVDIR64B);
+		F(CLDEMOTE) | F(MOVDIRI) | F(MOVDIR64B) | F(SHSTK);
 
 	/* cpuid 7.0.edx*/
 	const u32 kvm_cpuid_7_0_edx_x86_features =
 		F(AVX512_4VNNIW) | F(AVX512_4FMAPS) | F(SPEC_CTRL) |
-		F(SPEC_CTRL_SSBD) | F(ARCH_CAPABILITIES) | F(INTEL_STIBP);
+		F(SPEC_CTRL_SSBD) | F(ARCH_CAPABILITIES) | F(INTEL_STIBP) |
+		F(IBT);
 
 	/* all calls to cpuid_count() should be made on the same cpu */
 	get_cpu();
@@ -565,44 +615,23 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
 		break;
 	}
 	case 0xd: {
-		int idx, i;
-		u64 supported = kvm_supported_xcr0();
+		u64 u_supported = kvm_supported_xcr0();
+		u64 s_supported = kvm_supported_xss();
+		u32 eax_mask = kvm_cpuid_D_1_eax_x86_features;
 
-		entry->eax &= supported;
-		entry->ebx = xstate_required_size(supported, false);
+		entry->eax &= u_supported;
+		entry->ebx = xstate_required_size(u_supported, false);
 		entry->ecx = entry->ebx;
-		entry->edx &= supported >> 32;
+		entry->edx &= u_supported >> 32;
 		entry->flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
-		if (!supported)
+
+		if (!u_supported && !s_supported)
 			break;
 
-		for (idx = 1, i = 1; idx < 64; ++idx) {
-			u64 mask = ((u64)1 << idx);
-			if (*nent >= maxnent)
-				goto out;
+		if (__do_cpuid_dx_leaf(entry, nent, maxnent, s_supported,
+				       u_supported, eax_mask) < 0)
+			goto out;
 
-			do_cpuid_1_ent(&entry[i], function, idx);
-			if (idx == 1) {
-				entry[i].eax &= kvm_cpuid_D_1_eax_x86_features;
-				cpuid_mask(&entry[i].eax, CPUID_D_1_EAX);
-				entry[i].ebx = 0;
-				if (entry[i].eax & (F(XSAVES)|F(XSAVEC)))
-					entry[i].ebx =
-						xstate_required_size(supported,
-								     true);
-			} else {
-				if (entry[i].eax == 0 || !(supported & mask))
-					continue;
-				if (WARN_ON_ONCE(entry[i].ecx & 1))
-					continue;
-			}
-			entry[i].ecx = 0;
-			entry[i].edx = 0;
-			entry[i].flags |=
-			       KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
-			++*nent;
-			++i;
-		}
 		break;
 	}
 	/* Intel PT */
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 7c015416fd58..574428375ff9 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -1637,6 +1637,11 @@ static inline bool vmx_feature_control_msr_valid(struct kvm_vcpu *vcpu,
 	return !(val & ~valid_bits);
 }
 
+static __always_inline u64 vmx_supported_xss(void)
+{
+	return host_xss;
+}
+
 static int vmx_get_msr_feature(struct kvm_msr_entry *msr)
 {
 	switch (msr->index) {
@@ -7711,6 +7716,7 @@ static struct kvm_x86_ops vmx_x86_ops __ro_after_init = {
 	.set_nested_state = NULL,
 	.get_vmcs12_pages = NULL,
 	.nested_enable_evmcs = NULL,
+	.supported_xss = vmx_supported_xss,
 };
 
 static void vmx_cleanup_l1d_flush(void)
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index 28406aa1136d..e96616149f84 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -288,6 +288,10 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu, unsigned long cr2,
 				| XFEATURE_MASK_YMM | XFEATURE_MASK_BNDREGS \
 				| XFEATURE_MASK_BNDCSR | XFEATURE_MASK_AVX512 \
 				| XFEATURE_MASK_PKRU)
+
+#define KVM_SUPPORTED_XSS	(XFEATURE_MASK_CET_USER \
+				| XFEATURE_MASK_CET_KERNEL)
+
 extern u64 host_xcr0;
 
 extern u64 kvm_supported_xcr0(void);
-- 
2.17.2