[PATCH kvmtool v3 8/9] arm64: Add SVE support

Dave Martin
2019-05-30T15:14:25Z

This patch adds --enable-sve/--disable-sve command line options to
allow the user to control whether the Scalable Vector Extension is
made available to the guest.

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.

By default, SVE is enabled for the guest if the host supports it.

Signed-off-by: Dave Martin <Dave.Martin@arm.com>
---
arm/aarch32/include/kvm/kvm-cpu-arch.h | 4 +++
arm/aarch64/include/kvm/kvm-config-arch.h | 6 ++++-
arm/aarch64/include/kvm/kvm-cpu-arch.h | 1 +
arm/aarch64/kvm-cpu.c | 41 +++++++++++++++++++++++++++++++
arm/include/arm-common/kvm-config-arch.h | 2 ++
arm/kvm-cpu.c | 3 +++
6 files changed, 56 insertions(+), 1 deletion(-)

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-config-arch.h b/arm/aarch64/include/kvm/kvm-config-arch.h
index fe1699d..41e9d05 100644
--- a/arm/aarch64/include/kvm/kvm-config-arch.h
+++ b/arm/aarch64/include/kvm/kvm-config-arch.h
@@ -12,7 +12,11 @@
OPT_BOOLEAN('\0', "enable-ptrauth", &(cfg)->enable_ptrauth, \
"Enable pointer authentication for the guest"), \
OPT_BOOLEAN('\0', "disable-ptrauth", &(cfg)->disable_ptrauth, \
- "Disable pointer authentication for the guest"),
+ "Disable pointer authentication for the guest"), \
+ OPT_BOOLEAN('\0', "enable-sve", &(cfg)->enable_sve, \
+ "Enable SVE for the guest"), \
+ OPT_BOOLEAN('\0', "disable-sve", &(cfg)->disable_sve, \
+ "Disable SVE for the guest"),

#include "arm-common/kvm-config-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 08e4fd5..cdfb22e 100644
--- a/arm/aarch64/kvm-cpu.c
+++ b/arm/aarch64/kvm-cpu.c
@@ -152,9 +152,50 @@ static void select_ptrauth_feature(struct kvm *kvm, struct kvm_vcpu_init *init)
}
}

+static void select_sve_feature(struct kvm *kvm, struct kvm_vcpu_init *init)
+{
+ bool supported;
+
+ if (kvm->cfg.arch.enable_sve && kvm->cfg.arch.disable_sve)
+ die("--enable-sve conflicts with --disable-sve");
+
+ supported = kvm__supports_extension(kvm, KVM_CAP_ARM_SVE);
+
+ if (kvm->cfg.arch.enable_sve && !supported)
+ die("--enable-sve not supported on this host");
+
+ /* Default SVE to on if available and not explicitly disabled */
+ if (supported && !kvm->cfg.arch.disable_sve) {
+ kvm->cfg.arch.enable_sve = true;
+ init->features[0] |= 1UL << KVM_ARM_VCPU_SVE;
+ }
+}
+
void kvm_cpu__select_features(struct kvm *kvm, struct kvm_vcpu_init *init)
{
select_ptrauth_feature(kvm, init);
+ select_sve_feature(kvm, init);
+}
+
+static int configure_sve(struct kvm_cpu *vcpu)
+{
+ 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;
+}
+
+int kvm_cpu__configure_features(struct kvm_cpu *vcpu)
+{
+ if (vcpu->kvm->cfg.arch.enable_sve)
+ if (configure_sve(vcpu))
+ return -1;
+
+ return 0;
}

void kvm_cpu__reset_vcpu(struct kvm_cpu *vcpu)
diff --git a/arm/include/arm-common/kvm-config-arch.h b/arm/include/arm-common/kvm-config-arch.h
index 1b4287d..40e3d1f 100644
--- a/arm/include/arm-common/kvm-config-arch.h
+++ b/arm/include/arm-common/kvm-config-arch.h
@@ -10,6 +10,8 @@ struct kvm_config_arch {
bool aarch32_guest;
bool has_pmuv3;
u64 kaslr_seed;
+ bool enable_sve;
+ bool disable_sve;
bool enable_ptrauth;
bool disable_ptrauth;
enum irqchip_type irqchip;
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