[PATCH v8 2/4] arm64: KVM: export the capability to set guest SError syndrome

[James Morse <james.morse@arm.com>]

From: Dongjiu Geng <gengdongjiu@huawei.com>

For the arm64 RAS Extension, user space can inject a virtual-SError
with specified ESR. So user space needs to know whether KVM support
to inject such SError, this interface adds this query for this capability.

KVM will check whether system support RAS Extension, if supported, KVM
returns true to user space, otherwise returns false.

Signed-off-by: Dongjiu Geng <gengdongjiu@huawei.com>
Reviewed-by: James Morse <james.morse@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
---
 Documentation/virtual/kvm/api.txt | 11 +++++++++++
 arch/arm64/kvm/reset.c            |  3 +++
 include/uapi/linux/kvm.h          |  1 +
 3 files changed, 15 insertions(+)

diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index e3940f8715a5..480fa64eb52a 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -4643,3 +4643,14 @@ This capability indicates that KVM supports paravirtualized Hyper-V TLB Flush
 hypercalls:
 HvFlushVirtualAddressSpace, HvFlushVirtualAddressSpaceEx,
 HvFlushVirtualAddressList, HvFlushVirtualAddressListEx.
+
+8.19 KVM_CAP_ARM_SET_SERROR_ESR
+
+Architectures: arm, arm64
+
+This capability indicates that userspace can specify the syndrome value reported
+to the guest OS when guest takes a virtual SError interrupt exception.
+If KVM has this capability, userspace can only specify the ISS field for the ESR
+syndrome, it can not specify the EC field which is not under control by KVM.
+If this virtual SError is taken to EL1 using AArch64, this value will be reported
+in ISS filed of ESR_EL1.
diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
index a3db01a28062..067c6ba969bd 100644
--- a/arch/arm64/kvm/reset.c
+++ b/arch/arm64/kvm/reset.c
@@ -77,6 +77,9 @@ 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_INJECT_SERROR_ESR:
+		r = cpus_have_const_cap(ARM64_HAS_RAS_EXTN);
+		break;
 	case KVM_CAP_SET_GUEST_DEBUG:
 	case KVM_CAP_VCPU_ATTRIBUTES:
 	case KVM_CAP_VCPU_EVENTS:
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index b6270a3b38e9..a7d9bc4e4068 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -949,6 +949,7 @@ struct kvm_ppc_resize_hpt {
 #define KVM_CAP_GET_MSR_FEATURES 153
 #define KVM_CAP_HYPERV_EVENTFD 154
 #define KVM_CAP_HYPERV_TLBFLUSH 155
+#define KVM_CAP_ARM_INJECT_SERROR_ESR 156
 
 #ifdef KVM_CAP_IRQ_ROUTING
 
-- 
2.18.0