Hi James,

On 2017/12/7 14:37, gengdongjiu wrote:

quoted

We need to tackle (1) and (3) separately. For (3) we need some API that lets
Qemu _trigger_ an SError in the guest, with a specified ESR. But, we don't have
a way of migrating pending SError yet... which is where I got stuck last time I
was looking at this.

I understand you most idea.

But In the Qemu one signal type can only correspond to one behavior, can not correspond to two behaviors,
otherwise Qemu will do not know how to do.

For the Qemu, if it receives the SIGBUS_MCEERR_AR signal, it will populate the CPER
records and inject a SEA to guest through KVM IOCTL "KVM_SET_ONE_REG"; if receives the SIGBUS_MCEERR_AO
signal, it will record the CPER and trigger a IRQ to notify guest, as shown below:

SIGBUS_MCEERR_AR trigger Synchronous External Abort.
SIGBUS_MCEERR_AO trigger GPIO IRQ.

For the SIGBUS_MCEERR_AO and SIGBUS_MCEERR_AR, we have already specify trigger method, which all

not involve _trigger_ an SError.

so there is no chance for Qemu to trigger the SError when gets the SIGBUS_MCEERR_A{O,R}.

As I explained above:

If Qemu received SIGBUS_MCEERR_AR, it will record CPER and trigger Synchronous External Abort;
If Qemu received SIGBUS_MCEERR_AO, it will record CPER and trigger GPIO IRQ;
So Qemu does not know when to _trigger_ an SError.

so here I "return a error" to Qemu if ghes_notify_sei() return failure in [1], if you opposed KVM "return error",
do you have a better idea about it? thanks

About the way of migrating pending SError, I think it is a separate case, because Qemu still does not know
how and when to trigger the SError.

[1]:
static int kvm_handle_guest_sei(struct kvm_vcpu *vcpu, struct kvm_run *run)
{
        .......................
+       case ESR_ELx_AET_UER:   /* The error has not been propagated */
+               /*
+                * Userspace only handle the guest SError Interrupt(SEI) if the
+                * error has not been propagated
+                */
+               run->exit_reason = KVM_EXIT_EXCEPTION;
+               run->ex.exception = ESR_ELx_EC_SERROR;
+               run->ex.error_code = KVM_SEI_SEV_RECOVERABLE;
+               return 0;
        .......................
}