From: Christoffer Dall <christoffer.dall@xxxxxxx>
Introduce the feature bit and a primitive that checks if the feature is
set behind a static key check based on the cpus_have_const_cap check.
Checking nested_virt_in_use() on systems without nested virt enabled
should have neglgible overhead.
We don't yet allow userspace to actually set this feature.
Signed-off-by: Christoffer Dall <christoffer.dall@xxxxxxx>
Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
---
arch/arm64/include/asm/kvm_nested.h | 14 ++++++++++++++
arch/arm64/include/uapi/asm/kvm.h | 1 +
2 files changed, 15 insertions(+)
create mode 100644 arch/arm64/include/asm/kvm_nested.h
diff --git a/arch/arm64/include/asm/kvm_nested.h b/arch/arm64/include/asm/kvm_nested.h
new file mode 100644
index 000000000000..1028ac65a897
--- /dev/null
+++ b/arch/arm64/include/asm/kvm_nested.h
@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ARM64_KVM_NESTED_H
+#define __ARM64_KVM_NESTED_H
+
+#include <linux/kvm_host.h>
+
+static inline bool nested_virt_in_use(const struct kvm_vcpu *vcpu)
+{
+ return (!__is_defined(__KVM_NVHE_HYPERVISOR__) &&
+ cpus_have_final_cap(ARM64_HAS_NESTED_VIRT) &&
+ test_bit(KVM_ARM_VCPU_HAS_EL2, vcpu->arch.features));
+}
+
+#endif /* __ARM64_KVM_NESTED_H */
diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
index 24223adae150..fe3cb67f0d26 100644
--- a/arch/arm64/include/uapi/asm/kvm.h
+++ b/arch/arm64/include/uapi/asm/kvm.h
@@ -106,6 +106,7 @@ struct kvm_regs {
#define KVM_ARM_VCPU_SVE 4 /* enable SVE for this CPU */
#define KVM_ARM_VCPU_PTRAUTH_ADDRESS 5 /* VCPU uses address authentication */
#define KVM_ARM_VCPU_PTRAUTH_GENERIC 6 /* VCPU uses generic authentication */
+#define KVM_ARM_VCPU_HAS_EL2 7 /* Support nested virtualization */
struct kvm_vcpu_init {
__u32 target;
--
2.29.2
