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 <marc.zyngier@xxxxxxx>
---
arch/arm/include/asm/kvm_nested.h | 9 +++++++++
arch/arm64/include/asm/kvm_nested.h | 13 +++++++++++++
arch/arm64/include/uapi/asm/kvm.h | 1 +
3 files changed, 23 insertions(+)
create mode 100644 arch/arm/include/asm/kvm_nested.h
create mode 100644 arch/arm64/include/asm/kvm_nested.h
diff --git a/arch/arm/include/asm/kvm_nested.h b/arch/arm/include/asm/kvm_nested.h
new file mode 100644
index 000000000000..124ff6445f8f
--- /dev/null
+++ b/arch/arm/include/asm/kvm_nested.h
@@ -0,0 +1,9 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ARM_KVM_NESTED_H
+#define __ARM_KVM_NESTED_H
+
+#include <linux/kvm_host.h>
+
+static inline bool nested_virt_in_use(const struct kvm_vcpu *vcpu) { return false; }
+
+#endif /* __ARM_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..8a3d121a0b42
--- /dev/null
+++ b/arch/arm64/include/asm/kvm_nested.h
@@ -0,0 +1,13 @@
+/* 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 cpus_have_const_cap(ARM64_HAS_NESTED_VIRT) &&
+ test_bit(KVM_ARM_VCPU_NESTED_VIRT, 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 d819a3e8b552..563e2a8bae93 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_NESTED_VIRT 7 /* Support nested virtualization */
struct kvm_vcpu_init {
__u32 target;
--
2.20.1
