KVM: arm64: Convert the SVE guest vcpu flag to a vm flag

The vcpu flag GUEST_HAS_SVE is per-vcpu, but it is based on what
is now a per-vm feature. Make the flag per-vm.

Signed-off-by: Fuad Tabba <tabba@google.com>
Link: https://lore.kernel.org/r/20241216105057.579031-17-tabba@google.com
Signed-off-by: Marc Zyngier <maz@kernel.org>

Author: Fuad Tabba

arch/arm64/include/asm/kvm_emulate.h

@@ -620,7 +620,7 @@ static __always_inline void kvm_write_cptr_el2(u64 val)
 }
 
 /* Resets the value of cptr_el2 when returning to the host. */
-static __always_inline void kvm_reset_cptr_el2(struct kvm_vcpu *vcpu)
+static __always_inline void __kvm_reset_cptr_el2(struct kvm *kvm)
 {
 	u64 val;
 
@@ -631,14 +631,14 @@ static __always_inline void kvm_reset_cptr_el2(struct kvm_vcpu *vcpu)
 	} else if (has_hvhe()) {
 		val = CPACR_ELx_FPEN;
 
-		if (!vcpu_has_sve(vcpu) || !guest_owns_fp_regs())
+		if (!kvm_has_sve(kvm) || !guest_owns_fp_regs())
 			val |= CPACR_ELx_ZEN;
 		if (cpus_have_final_cap(ARM64_SME))
 			val |= CPACR_ELx_SMEN;
 	} else {
 		val = CPTR_NVHE_EL2_RES1;
 
-		if (vcpu_has_sve(vcpu) && guest_owns_fp_regs())
+		if (kvm_has_sve(kvm) && guest_owns_fp_regs())
 			val |= CPTR_EL2_TZ;
 		if (!cpus_have_final_cap(ARM64_SME))
 			val |= CPTR_EL2_TSM;
@@ -647,6 +647,12 @@ static __always_inline void kvm_reset_cptr_el2(struct kvm_vcpu *vcpu)
 	kvm_write_cptr_el2(val);
 }
 
+#ifdef __KVM_NVHE_HYPERVISOR__
+#define kvm_reset_cptr_el2(v)	__kvm_reset_cptr_el2(kern_hyp_va((v)->kvm))
+#else
+#define kvm_reset_cptr_el2(v)	__kvm_reset_cptr_el2((v)->kvm)
+#endif
+
 /*
  * Returns a 'sanitised' view of CPTR_EL2, translating from nVHE to the VHE
  * format if E2H isn't set.

arch/arm64/include/asm/kvm_host.h

@@ -331,6 +331,8 @@ struct kvm_arch {
 #define KVM_ARCH_FLAG_ID_REGS_INITIALIZED		7
 	/* Fine-Grained UNDEF initialised */
 #define KVM_ARCH_FLAG_FGU_INITIALIZED			8
+	/* SVE exposed to guest */
+#define KVM_ARCH_FLAG_GUEST_HAS_SVE			9
 	unsigned long flags;
 
 	/* VM-wide vCPU feature set */
@@ -862,12 +864,10 @@ struct kvm_vcpu_arch {
 #define vcpu_set_flag(v, ...)	__vcpu_set_flag((v), __VA_ARGS__)
 #define vcpu_clear_flag(v, ...)	__vcpu_clear_flag((v), __VA_ARGS__)
 
-/* SVE exposed to guest */
-#define GUEST_HAS_SVE		__vcpu_single_flag(cflags, BIT(0))
+/* KVM_ARM_VCPU_INIT completed */
+#define VCPU_INITIALIZED	__vcpu_single_flag(cflags, BIT(0))
 /* SVE config completed */
 #define VCPU_SVE_FINALIZED	__vcpu_single_flag(cflags, BIT(1))
-/* KVM_ARM_VCPU_INIT completed */
-#define VCPU_INITIALIZED	__vcpu_single_flag(cflags, BIT(2))
 
 /* Exception pending */
 #define PENDING_EXCEPTION	__vcpu_single_flag(iflags, BIT(0))
@@ -956,8 +956,14 @@ struct kvm_vcpu_arch {
 				 KVM_GUESTDBG_USE_HW | \
 				 KVM_GUESTDBG_SINGLESTEP)
 
-#define vcpu_has_sve(vcpu) (system_supports_sve() &&			\
-			    vcpu_get_flag(vcpu, GUEST_HAS_SVE))
+#define kvm_has_sve(kvm)	(system_supports_sve() &&		\
+				 test_bit(KVM_ARCH_FLAG_GUEST_HAS_SVE, &(kvm)->arch.flags))
+
+#ifdef __KVM_NVHE_HYPERVISOR__
+#define vcpu_has_sve(vcpu)	kvm_has_sve(kern_hyp_va((vcpu)->kvm))
+#else
+#define vcpu_has_sve(vcpu)	kvm_has_sve((vcpu)->kvm)
+#endif
 
 #ifdef CONFIG_ARM64_PTR_AUTH
 #define vcpu_has_ptrauth(vcpu)						\

arch/arm64/kvm/hyp/nvhe/pkvm.c

@@ -248,10 +248,13 @@ void pkvm_put_hyp_vcpu(struct pkvm_hyp_vcpu *hyp_vcpu)
 static void pkvm_init_features_from_host(struct pkvm_hyp_vm *hyp_vm, const struct kvm *host_kvm)
 {
 	struct kvm *kvm = &hyp_vm->kvm;
+	unsigned long host_arch_flags = READ_ONCE(host_kvm->arch.flags);
 	DECLARE_BITMAP(allowed_features, KVM_VCPU_MAX_FEATURES);
 
 	/* No restrictions for non-protected VMs. */
 	if (!kvm_vm_is_protected(kvm)) {
+		hyp_vm->kvm.arch.flags = host_arch_flags;
+
 		bitmap_copy(kvm->arch.vcpu_features,
 			    host_kvm->arch.vcpu_features,
 			    KVM_VCPU_MAX_FEATURES);
@@ -271,8 +274,10 @@ static void pkvm_init_features_from_host(struct pkvm_hyp_vm *hyp_vm, const struc
 	if (kvm_pvm_ext_allowed(KVM_CAP_ARM_PTRAUTH_GENERIC))
 		set_bit(KVM_ARM_VCPU_PTRAUTH_GENERIC, allowed_features);
 
-	if (kvm_pvm_ext_allowed(KVM_CAP_ARM_SVE))
+	if (kvm_pvm_ext_allowed(KVM_CAP_ARM_SVE)) {
 		set_bit(KVM_ARM_VCPU_SVE, allowed_features);
+		kvm->arch.flags |= host_arch_flags & BIT(KVM_ARCH_FLAG_GUEST_HAS_SVE);
+	}
 
 	bitmap_and(kvm->arch.vcpu_features, host_kvm->arch.vcpu_features,
 		   allowed_features, KVM_VCPU_MAX_FEATURES);
@@ -308,10 +313,8 @@ static void pkvm_vcpu_init_sve(struct pkvm_hyp_vcpu *hyp_vcpu, struct kvm_vcpu *
 {
 	struct kvm_vcpu *vcpu = &hyp_vcpu->vcpu;
 
-	if (!vcpu_has_feature(vcpu, KVM_ARM_VCPU_SVE)) {
-		vcpu_clear_flag(vcpu, GUEST_HAS_SVE);
+	if (!vcpu_has_feature(vcpu, KVM_ARM_VCPU_SVE))
 		vcpu_clear_flag(vcpu, VCPU_SVE_FINALIZED);
-	}
 }
 
 static int init_pkvm_hyp_vcpu(struct pkvm_hyp_vcpu *hyp_vcpu,

arch/arm64/kvm/reset.c

@@ -85,7 +85,7 @@ static void kvm_vcpu_enable_sve(struct kvm_vcpu *vcpu)
 	 * KVM_REG_ARM64_SVE_VLS.  Allocation is deferred until
 	 * kvm_arm_vcpu_finalize(), which freezes the configuration.
 	 */
-	vcpu_set_flag(vcpu, GUEST_HAS_SVE);
+	set_bit(KVM_ARCH_FLAG_GUEST_HAS_SVE, &vcpu->kvm->arch.flags);
 }
 
 /*