[PATCH kvmtool v4 8/8] arm64: Add SVE support

[Dave Martin <Dave.Martin@arm.com>]

This patch enables the Scalable Vector Extension for the guest when
the host supports it.

This requires use of the new KVM_ARM_VCPU_FINALIZE ioctl before the
vcpu is runnable, so a new hook kvm_cpu__configure_features() is
added to provide an appropriate place to do this work.

Signed-off-by: Dave Martin <Dave.Martin@arm.com>

---

Changes since v3:

 * Drop command-line options and simply default SVE to on where
   supported.
---
 arm/aarch32/include/kvm/kvm-cpu-arch.h |  4 ++++
 arm/aarch64/include/kvm/kvm-cpu-arch.h |  1 +
 arm/aarch64/kvm-cpu.c                  | 18 ++++++++++++++++++
 arm/kvm-cpu.c                          |  3 +++
 4 files changed, 26 insertions(+)

diff --git a/arm/aarch32/include/kvm/kvm-cpu-arch.h b/arm/aarch32/include/kvm/kvm-cpu-arch.h
index 01983f0..780e0e2 100644
--- a/arm/aarch32/include/kvm/kvm-cpu-arch.h
+++ b/arm/aarch32/include/kvm/kvm-cpu-arch.h
@@ -15,5 +15,9 @@
 
 static inline void kvm_cpu__select_features(struct kvm *kvm,
 					    struct kvm_vcpu_init *init) { }
+static inline int kvm_cpu__configure_features(struct kvm_cpu *vcpu)
+{
+	return 0;
+}
 
 #endif /* KVM__KVM_CPU_ARCH_H */
diff --git a/arm/aarch64/include/kvm/kvm-cpu-arch.h b/arm/aarch64/include/kvm/kvm-cpu-arch.h
index e6875fc..8dfb82e 100644
--- a/arm/aarch64/include/kvm/kvm-cpu-arch.h
+++ b/arm/aarch64/include/kvm/kvm-cpu-arch.h
@@ -18,5 +18,6 @@
 #define ARM_CPU_CTRL_SCTLR_EL1	0
 
 void kvm_cpu__select_features(struct kvm *kvm, struct kvm_vcpu_init *init);
+int kvm_cpu__configure_features(struct kvm_cpu *vcpu);
 
 #endif /* KVM__KVM_CPU_ARCH_H */
diff --git a/arm/aarch64/kvm-cpu.c b/arm/aarch64/kvm-cpu.c
index 8c29a21..9f3e858 100644
--- a/arm/aarch64/kvm-cpu.c
+++ b/arm/aarch64/kvm-cpu.c
@@ -136,6 +136,24 @@ void kvm_cpu__select_features(struct kvm *kvm, struct kvm_vcpu_init *init)
 		init->features[0] |= 1UL << KVM_ARM_VCPU_PTRAUTH_ADDRESS;
 		init->features[0] |= 1UL << KVM_ARM_VCPU_PTRAUTH_GENERIC;
 	}
+
+	/* Enable SVE if available */
+	if (kvm__supports_extension(kvm, KVM_CAP_ARM_SVE))
+		init->features[0] |= 1UL << KVM_ARM_VCPU_SVE;
+}
+
+int kvm_cpu__configure_features(struct kvm_cpu *vcpu)
+{
+	if (kvm__supports_extension(vcpu->kvm, KVM_CAP_ARM_SVE)) {
+		int feature = KVM_ARM_VCPU_SVE;
+
+		if (ioctl(vcpu->vcpu_fd, KVM_ARM_VCPU_FINALIZE, &feature)) {
+			pr_err("KVM_ARM_VCPU_FINALIZE: %s", strerror(errno));
+			return -1;
+		}
+	}
+
+	return 0;
 }
 
 void kvm_cpu__reset_vcpu(struct kvm_cpu *vcpu)
diff --git a/arm/kvm-cpu.c b/arm/kvm-cpu.c
index 1652f6f..554414f 100644
--- a/arm/kvm-cpu.c
+++ b/arm/kvm-cpu.c
@@ -124,6 +124,9 @@ struct kvm_cpu *kvm_cpu__arch_init(struct kvm *kvm, unsigned long cpu_id)
 	vcpu->cpu_compatible	= target->compatible;
 	vcpu->is_running	= true;
 
+	if (kvm_cpu__configure_features(vcpu))
+		die("Unable to configure requested vcpu features");
+
 	return vcpu;
 }
 
-- 
2.1.4

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