On 02/05/2017 09:56, Christoffer Dall wrote:

Hi Dongjiu,

Please send a cover letter for patch series with more than a single
patch.

The subject and description of these patches are also misleading.
Hopefully this is in no way tied to kvmtool, but to userspace
generically, for example also to be used by QEMU?

Yes, QEMU already has a similar capability on x86.

Does ARM support background scrubbing of memory to detect errors?  If
so, are there any plans to support action-optional SIGBUS on ARM?

Paolo

On Sun, Apr 30, 2017 at 01:37:55PM +0800, Dongjiu Geng wrote:

quoted

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

the APP ?

the CPU's capacity?

quoted

Signed-off-by: Dongjiu Geng <redacted>
---
 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;

You need to document this capability and API in
Documentation/virtual/kvm/api.txt and explain how this works.

quoted

 	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

Thanks,
-Christoffer