On 2018/6/11 21:36, James Morse wrote:

Hi Dongjiu Geng,

On 09/06/18 13:40, Marc Zyngier wrote:

quoted

On Fri, 08 Jun 2018 20:48:40 +0100, Dongjiu Geng wrote:

quoted

For the migrating VMs, user space may need to know the exception
state. For example, in the machine A, KVM make an SError pending,
when migrate to B, KVM also needs to pend an SError.

This new IOCTL exports user-invisible states related to SError.
Together with appropriate user space changes, user space can get/set
the SError exception state to do migrate/snapshot/suspend.

quoted

quoted

diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
index 04b3256..df4faee 100644
--- a/arch/arm64/include/uapi/asm/kvm.h
+++ b/arch/arm64/include/uapi/asm/kvm.h

@@ -153,6 +154,18 @@ struct kvm_sync_regs {
 struct kvm_arch_memory_slot {
 };
 
+/* for KVM_GET/SET_VCPU_EVENTS */
+struct kvm_vcpu_events {
+	struct {
+		__u8 serror_pending;
+		__u8 serror_has_esr;
+		/* Align it to 8 bytes */
+		__u8 pad[6];
+		__u64 serror_esr;
+	} exception;
+	__u32 reserved[12];
+};

quoted

quoted

diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
index 56a0260..4426915 100644
--- a/arch/arm64/kvm/guest.c
+++ b/arch/arm64/kvm/guest.c

quoted

quoted

+int kvm_arm_vcpu_set_events(struct kvm_vcpu *vcpu,
+			struct kvm_vcpu_events *events)
+{
+	bool serror_pending = events->exception.serror_pending;
+	bool has_esr = events->exception.serror_has_esr;
+
+	if (serror_pending && has_esr) {
+		if (!cpus_have_const_cap(ARM64_HAS_RAS_EXTN))
+			return -EINVAL;
+
+		kvm_set_sei_esr(vcpu, events->exception.serror_esr);
+	} else if (serror_pending) {
+		kvm_inject_vabt(vcpu);
+	}
+
+	return 0;

There was an earlier request to check that all the padding is set to
zero. I still think this makes sense.

I agree, not just the exception.padding[], but reserved[] too.

  Ok, thanks for the reminder again.

Thanks,

James

.