[PATCH v4 1/3] arm64: kvm: support user space to detect RAS extension feature

[Dongjiu Geng]

Handle userspace's detection for RAS extension, because sometimes
the userspace needs to know the CPU's capacity

Signed-off-by: Dongjiu Geng <gengdongjiu@xxxxxxxxxx>
---
 arch/arm64/kvm/reset.c   | 11 +++++++++++
 include/uapi/linux/kvm.h |  1 +
 2 files changed, 12 insertions(+)

diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
index d9e9697..1004039 100644
--- a/arch/arm64/kvm/reset.c
+++ b/arch/arm64/kvm/reset.c
@@ -64,6 +64,14 @@ static bool cpu_has_32bit_el1(void)
 	return !!(pfr0 & 0x20);
 }
 
+static bool kvm_arm_support_ras_extension(void)
+{
+	u64 pfr0;
+
+	pfr0 = read_system_reg(SYS_ID_AA64PFR0_EL1);
+	return !!(pfr0 & 0x10000000);
+}
+
 /**
  * kvm_arch_dev_ioctl_check_extension
  *
@@ -87,6 +95,9 @@ int kvm_arch_dev_ioctl_check_extension(struct kvm *kvm, long ext)
 	case KVM_CAP_ARM_PMU_V3:
 		r = kvm_arm_support_pmu_v3();
 		break;
+	case KVM_CAP_ARM_RAS_EXTENSION:
+		r = kvm_arm_support_ras_extension();
+		break;
 	case KVM_CAP_SET_GUEST_DEBUG:
 	case KVM_CAP_VCPU_ATTRIBUTES:
 		r = 1;
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index f51d508..27fe556 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -883,6 +883,7 @@ struct kvm_ppc_resize_hpt {
 #define KVM_CAP_PPC_MMU_RADIX 134
 #define KVM_CAP_PPC_MMU_HASH_V3 135
 #define KVM_CAP_IMMEDIATE_EXIT 136
+#define KVM_CAP_ARM_RAS_EXTENSION 137
 
 #ifdef KVM_CAP_IRQ_ROUTING
 
-- 
2.10.1