Hi Peter,
Thanks for the comments and mail.
>
> On 22 November 2018 at 10:28, Peter Maydell <peter.maydell@xxxxxxxxxx> wrote:
> > On 22 November 2018 at 03:05, gengdongjiu <gengdongjiu@xxxxxxxxxx> wrote:
> >>> >
> >>> Shouldn't there be something in here to say "only report this error to the guest if we are actually reporting RAS errors to the guest" ?
> >>
> >> Yes, We can say something that such as "report this error to the guest", because this error is indeed triggered by guest, which is guest
> error.
> >
> > I'm afraid I don't really understand what you mean. Could you try
> > rephrasing it?
> >
> > My understanding was:
> > * we get this signal if there is a RAS error in the host memory
> > * if we are exposing RAS errors to the guest (ie we have
> > told it that in the ACPI table we passed it at startup)
> > then we should pass on this error to the guest
> >
> > but that these are two different conditions.
> >
> > If the host hardware detects a RAS error in memory used by the guest
> > but the guest is not being told about RAS errors, then we cannot
> > report the error: we have no mechanism to do so, and the guest is not
> > expecting it.
>
> If you look at the x86 version of this function you can see that it tests (env->mcg_cap & MCG_SER_P), which I think is the equivalent x86 "is
> the guest CPU/config one we can report these errors to" test.
MCG_SER_P (software error recovery support present) flag indicates (when set) that the processor supports software error recovery.
env->mcg_cap 's value should be got from KVM as shown in the QEMU code[1], it indicates whether the KVM support software error recovery.
[1]:
-------------------------------------------------------------------------------------------------------------
ret = kvm_get_mce_cap_supported(cs->kvm_state, &mcg_cap, &banks);
if (ret < 0) {
fprintf(stderr, "kvm_get_mce_cap_supported: %s", strerror(-ret));
return ret;
}
-------------------------------------------------------------------------------------------------------------
[2]:
--------------------------------------------------------------------------------------------------------------
void kvm_arch_on_sigbus_vcpu(CPUState *c, int code, void *addr)
{
...........................
if (ram_addr != RAM_ADDR_INVALID &&
kvm_physical_memory_addr_from_host(c->kvm_state, addr, &paddr)) {
If it got to here, it means the host hardware detects a RAS error in memory used by the guest using above two judgments.
Maybe we can test/check whether KVM supports software error recovery in [3]
}
return;
.........................
}
}
---------------------------------------------------------------------------------------------------------------
[3]:
If we check it as x86, we can check that whether KVM supports software recovery though IOCTL, for example.
int r = kvm_ioctl(s, XXXXXX_GET_SER_CAP_SUPPORTED, seg_cap);
--------------
if (seg_cap && addr) {
------------------------
}
>
> thanks
> -- PMM
