On Thu, Nov 02, 2023, Paolo Bonzini wrote:
> On 11/2/23 10:35, Huang, Kai wrote:
> > IIUC KVM can already handle the case of poisoned
> > page by sending signal to user app:
> >
> > static int kvm_handle_error_pfn(struct kvm_vcpu *vcpu, struct
> > kvm_page_fault *fault) {
> > ...
> >
> > if (fault->pfn == KVM_PFN_ERR_HWPOISON) {
> > kvm_send_hwpoison_signal(fault->slot, fault->gfn);
No, this doesn't work, because that signals the host virtual address
unsigned long hva = gfn_to_hva_memslot(slot, gfn);
send_sig_mceerr(BUS_MCEERR_AR, (void __user *)hva, PAGE_SHIFT, current);
which is the *shared* page.
> > return RET_PF_RETRY;
> > }
> > }
>
> EHWPOISON is not implemented by this series, so it should be left out of the
> documentation.
EHWPOISON *is* implemented. kvm_gmem_get_pfn() returns -EWPOISON as appropriate,
and kvm_faultin_pfn() returns that directly without going through kvm_handle_error_pfn().
kvm_faultin_pfn_private()
|
|-> kvm_gmem_get_pfn()
|
|-> if (folio_test_hwpoison(folio)) {
r = -EHWPOISON;
goto out_unlock;
}
|
|-> r = kvm_gmem_get_pfn(vcpu->kvm, fault->slot, fault->gfn, &fault->pfn,
&max_order);
if (r) {
kvm_mmu_prepare_memory_fault_exit(vcpu, fault);
return r;
}
|
|-> ret = __kvm_faultin_pfn(vcpu, fault);
if (ret != RET_PF_CONTINUE)
return ret;
if (unlikely(is_error_pfn(fault->pfn)))
return kvm_handle_error_pfn(vcpu, fault);
