KVM: x86: Add a struct to consolidate host values, e.g. EFER, XCR0, etc...

Add "struct kvm_host_values kvm_host" to hold the various host values
that KVM snapshots during initialization.  Bundling the host values into
a single struct simplifies adding new MSRs and other features with host
state/values that KVM cares about, and provides a one-stop shop.  E.g.
adding a new value requires one line, whereas tracking each value
individual often requires three: declaration, definition, and export.

No functional change intended.

Link: https://lore.kernel.org/r/20240423221521.2923759-2-seanjc@google.comSigned-off-by: Sean Christopherson <seanjc@google.com>

arch/x86/include/asm/kvm_host.h

@@ -1853,7 +1853,6 @@ struct kvm_arch_async_pf {
 };
 
 extern u32 __read_mostly kvm_nr_uret_msrs;
-extern u64 __read_mostly host_efer;
 extern bool __read_mostly allow_smaller_maxphyaddr;
 extern bool __read_mostly enable_apicv;
 extern struct kvm_x86_ops kvm_x86_ops;

arch/x86/kvm/svm/sev.c

@@ -3324,7 +3324,7 @@ void sev_es_prepare_switch_to_guest(struct vcpu_svm *svm, struct sev_es_save_are
 	 */
 	hostsa->xcr0 = xgetbv(XCR_XFEATURE_ENABLED_MASK);
 	hostsa->pkru = read_pkru();
-	hostsa->xss = host_xss;
+	hostsa->xss = kvm_host.xss;
 
 	/*
 	 * If DebugSwap is enabled, debug registers are loaded but NOT saved by

arch/x86/kvm/vmx/nested.c

@@ -2422,7 +2422,7 @@ static void prepare_vmcs02_early(struct vcpu_vmx *vmx, struct loaded_vmcs *vmcs0
 	if (cpu_has_load_ia32_efer()) {
 		if (guest_efer & EFER_LMA)
 			exec_control |= VM_ENTRY_IA32E_MODE;
-		if (guest_efer != host_efer)
+		if (guest_efer != kvm_host.efer)
 			exec_control |= VM_ENTRY_LOAD_IA32_EFER;
 	}
 	vm_entry_controls_set(vmx, exec_control);
@@ -2435,7 +2435,7 @@ static void prepare_vmcs02_early(struct vcpu_vmx *vmx, struct loaded_vmcs *vmcs0
 	 * bits may be modified by vmx_set_efer() in prepare_vmcs02().
 	 */
 	exec_control = __vm_exit_controls_get(vmcs01);
-	if (cpu_has_load_ia32_efer() && guest_efer != host_efer)
+	if (cpu_has_load_ia32_efer() && guest_efer != kvm_host.efer)
 		exec_control |= VM_EXIT_LOAD_IA32_EFER;
 	else
 		exec_control &= ~VM_EXIT_LOAD_IA32_EFER;
@@ -4662,7 +4662,7 @@ static inline u64 nested_vmx_get_vmcs01_guest_efer(struct vcpu_vmx *vmx)
 		return vmcs_read64(GUEST_IA32_EFER);
 
 	if (cpu_has_load_ia32_efer())
-		return host_efer;
+		return kvm_host.efer;
 
 	for (i = 0; i < vmx->msr_autoload.guest.nr; ++i) {
 		if (vmx->msr_autoload.guest.val[i].index == MSR_EFER)
@@ -4673,7 +4673,7 @@ static inline u64 nested_vmx_get_vmcs01_guest_efer(struct vcpu_vmx *vmx)
 	if (efer_msr)
 		return efer_msr->data;
 
-	return host_efer;
+	return kvm_host.efer;
 }
 
 static void nested_vmx_restore_host_state(struct kvm_vcpu *vcpu)

arch/x86/kvm/vmx/vmx.c

@@ -259,7 +259,7 @@ static int vmx_setup_l1d_flush(enum vmx_l1d_flush_state l1tf)
 		return 0;
 	}
 
-	if (host_arch_capabilities & ARCH_CAP_SKIP_VMENTRY_L1DFLUSH) {
+	if (kvm_host.arch_capabilities & ARCH_CAP_SKIP_VMENTRY_L1DFLUSH) {
 		l1tf_vmx_mitigation = VMENTER_L1D_FLUSH_NOT_REQUIRED;
 		return 0;
 	}
@@ -404,7 +404,7 @@ static void vmx_update_fb_clear_dis(struct kvm_vcpu *vcpu, struct vcpu_vmx *vmx)
 	 * and VM-Exit.
 	 */
 	vmx->disable_fb_clear = !cpu_feature_enabled(X86_FEATURE_CLEAR_CPU_BUF) &&
-				(host_arch_capabilities & ARCH_CAP_FB_CLEAR_CTRL) &&
+				(kvm_host.arch_capabilities & ARCH_CAP_FB_CLEAR_CTRL) &&
 				!boot_cpu_has_bug(X86_BUG_MDS) &&
 				!boot_cpu_has_bug(X86_BUG_TAA);
 
@@ -1123,12 +1123,12 @@ static bool update_transition_efer(struct vcpu_vmx *vmx)
 	 * atomically, since it's faster than switching it manually.
 	 */
 	if (cpu_has_load_ia32_efer() ||
-	    (enable_ept && ((vmx->vcpu.arch.efer ^ host_efer) & EFER_NX))) {
+	    (enable_ept && ((vmx->vcpu.arch.efer ^ kvm_host.efer) & EFER_NX))) {
 		if (!(guest_efer & EFER_LMA))
 			guest_efer &= ~EFER_LME;
-		if (guest_efer != host_efer)
+		if (guest_efer != kvm_host.efer)
 			add_atomic_switch_msr(vmx, MSR_EFER,
-					      guest_efer, host_efer, false);
+					      guest_efer, kvm_host.efer, false);
 		else
 			clear_atomic_switch_msr(vmx, MSR_EFER);
 		return false;
@@ -1141,7 +1141,7 @@ static bool update_transition_efer(struct vcpu_vmx *vmx)
 	clear_atomic_switch_msr(vmx, MSR_EFER);
 
 	guest_efer &= ~ignore_bits;
-	guest_efer |= host_efer & ignore_bits;
+	guest_efer |= kvm_host.efer & ignore_bits;
 
 	vmx->guest_uret_msrs[i].data = guest_efer;
 	vmx->guest_uret_msrs[i].mask = ~ignore_bits;
@@ -4357,7 +4357,7 @@ void vmx_set_constant_host_state(struct vcpu_vmx *vmx)
 	}
 
 	if (cpu_has_load_ia32_efer())
-		vmcs_write64(HOST_IA32_EFER, host_efer);
+		vmcs_write64(HOST_IA32_EFER, kvm_host.efer);
 }
 
 void set_cr4_guest_host_mask(struct vcpu_vmx *vmx)

arch/x86/kvm/x86.c

@@ -100,6 +100,9 @@
 struct kvm_caps kvm_caps __read_mostly;
 EXPORT_SYMBOL_GPL(kvm_caps);
 
+struct kvm_host_values kvm_host __read_mostly;
+EXPORT_SYMBOL_GPL(kvm_host);
+
 #define  ERR_PTR_USR(e)  ((void __user *)ERR_PTR(e))
 
 #define emul_to_vcpu(ctxt) \
@@ -229,21 +232,12 @@ static struct kvm_user_return_msrs __percpu *user_return_msrs;
 				| XFEATURE_MASK_BNDCSR | XFEATURE_MASK_AVX512 \
 				| XFEATURE_MASK_PKRU | XFEATURE_MASK_XTILE)
 
-u64 __read_mostly host_efer;
-EXPORT_SYMBOL_GPL(host_efer);
-
 bool __read_mostly allow_smaller_maxphyaddr = 0;
 EXPORT_SYMBOL_GPL(allow_smaller_maxphyaddr);
 
 bool __read_mostly enable_apicv = true;
 EXPORT_SYMBOL_GPL(enable_apicv);
 
-u64 __read_mostly host_xss;
-EXPORT_SYMBOL_GPL(host_xss);
-
-u64 __read_mostly host_arch_capabilities;
-EXPORT_SYMBOL_GPL(host_arch_capabilities);
-
 const struct _kvm_stats_desc kvm_vm_stats_desc[] = {
 	KVM_GENERIC_VM_STATS(),
 	STATS_DESC_COUNTER(VM, mmu_shadow_zapped),
@@ -317,8 +311,6 @@ const struct kvm_stats_header kvm_vcpu_stats_header = {
 		       sizeof(kvm_vcpu_stats_desc),
 };
 
-u64 __read_mostly host_xcr0;
-
 static struct kmem_cache *x86_emulator_cache;
 
 /*
@@ -1025,11 +1017,11 @@ void kvm_load_guest_xsave_state(struct kvm_vcpu *vcpu)
 
 	if (kvm_is_cr4_bit_set(vcpu, X86_CR4_OSXSAVE)) {
 
-		if (vcpu->arch.xcr0 != host_xcr0)
+		if (vcpu->arch.xcr0 != kvm_host.xcr0)
 			xsetbv(XCR_XFEATURE_ENABLED_MASK, vcpu->arch.xcr0);
 
 		if (guest_can_use(vcpu, X86_FEATURE_XSAVES) &&
-		    vcpu->arch.ia32_xss != host_xss)
+		    vcpu->arch.ia32_xss != kvm_host.xss)
 			wrmsrl(MSR_IA32_XSS, vcpu->arch.ia32_xss);
 	}
 
@@ -1056,12 +1048,12 @@ void kvm_load_host_xsave_state(struct kvm_vcpu *vcpu)
 
 	if (kvm_is_cr4_bit_set(vcpu, X86_CR4_OSXSAVE)) {
 
-		if (vcpu->arch.xcr0 != host_xcr0)
-			xsetbv(XCR_XFEATURE_ENABLED_MASK, host_xcr0);
+		if (vcpu->arch.xcr0 != kvm_host.xcr0)
+			xsetbv(XCR_XFEATURE_ENABLED_MASK, kvm_host.xcr0);
 
 		if (guest_can_use(vcpu, X86_FEATURE_XSAVES) &&
-		    vcpu->arch.ia32_xss != host_xss)
-			wrmsrl(MSR_IA32_XSS, host_xss);
+		    vcpu->arch.ia32_xss != kvm_host.xss)
+			wrmsrl(MSR_IA32_XSS, kvm_host.xss);
 	}
 
 }
@@ -1628,7 +1620,7 @@ static bool kvm_is_immutable_feature_msr(u32 msr)
 
 static u64 kvm_get_arch_capabilities(void)
 {
-	u64 data = host_arch_capabilities & KVM_SUPPORTED_ARCH_CAP;
+	u64 data = kvm_host.arch_capabilities & KVM_SUPPORTED_ARCH_CAP;
 
 	/*
 	 * If nx_huge_pages is enabled, KVM's shadow paging will ensure that
@@ -9781,19 +9773,19 @@ int kvm_x86_vendor_init(struct kvm_x86_init_ops *ops)
 	kvm_caps.supported_mce_cap = MCG_CTL_P | MCG_SER_P;
 
 	if (boot_cpu_has(X86_FEATURE_XSAVE)) {
-		host_xcr0 = xgetbv(XCR_XFEATURE_ENABLED_MASK);
-		kvm_caps.supported_xcr0 = host_xcr0 & KVM_SUPPORTED_XCR0;
+		kvm_host.xcr0 = xgetbv(XCR_XFEATURE_ENABLED_MASK);
+		kvm_caps.supported_xcr0 = kvm_host.xcr0 & KVM_SUPPORTED_XCR0;
 	}
 
-	rdmsrl_safe(MSR_EFER, &host_efer);
+	rdmsrl_safe(MSR_EFER, &kvm_host.efer);
 
 	if (boot_cpu_has(X86_FEATURE_XSAVES))
-		rdmsrl(MSR_IA32_XSS, host_xss);
+		rdmsrl(MSR_IA32_XSS, kvm_host.xss);
 
 	kvm_init_pmu_capability(ops->pmu_ops);
 
 	if (boot_cpu_has(X86_FEATURE_ARCH_CAPABILITIES))
-		rdmsrl(MSR_IA32_ARCH_CAPABILITIES, host_arch_capabilities);
+		rdmsrl(MSR_IA32_ARCH_CAPABILITIES, kvm_host.arch_capabilities);
 
 	r = ops->hardware_setup();
 	if (r != 0)

arch/x86/kvm/x86.h

@@ -33,6 +33,13 @@ struct kvm_caps {
 	u64 supported_perf_cap;
 };
 
+struct kvm_host_values {
+	u64 efer;
+	u64 xcr0;
+	u64 xss;
+	u64 arch_capabilities;
+};
+
 void kvm_spurious_fault(void);
 
 #define KVM_NESTED_VMENTER_CONSISTENCY_CHECK(consistency_check)		\
@@ -325,11 +332,8 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
 			    int emulation_type, void *insn, int insn_len);
 fastpath_t handle_fastpath_set_msr_irqoff(struct kvm_vcpu *vcpu);
 
-extern u64 host_xcr0;
-extern u64 host_xss;
-extern u64 host_arch_capabilities;
-
 extern struct kvm_caps kvm_caps;
+extern struct kvm_host_values kvm_host;
 
 extern bool enable_pmu;