Re: [PATCH v13 09/35] KVM: Add KVM_EXIT_MEMORY_FAULT exit to report faults to userspace
From: Sean Christopherson <seanjc@google.com>
Date: 2023-11-02 15:44:55
Also in:
kvm, kvm-riscv, kvmarm, linux-arm-kernel, linux-fsdevel, linux-mips, linux-mm, linux-riscv, lkml
On Thu, Nov 02, 2023, Paolo Bonzini wrote:
On 11/2/23 10:35, Huang, Kai wrote:quoted
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.
quoted
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);