On 02/07/2018 10:16 PM, Paolo Bonzini wrote:
On 07/02/2018 07:25, Wanpeng Li wrote:
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 786cd00..445e702 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -7458,6 +7458,11 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
goto out;
}
+ if (unlikely(vcpu->run->exit_reason == KVM_EXIT_SHUTDOWN)) {
+ r = -EINVAL;
+ goto out;
+ }
+
if (vcpu->run->kvm_dirty_regs) {
r = sync_regs(vcpu);
if (r != 0)
This most likely breaks triple faults in the usual case where they
should result in resetting the system; the KVM API doesn't say that you
should clear vcpu->run->exit_reason before entering.
What exactly causes the EPT misconfig to reach the WARN? That is, how
does kvm_mmu_page_fault end up returning a negative errno value? If I
read the code correctly only tdp_page_fault can do so, so my guess would
be kvm_handle_bad_page:
if (pfn == KVM_PFN_ERR_RO_FAULT)
return RET_PF_EMULATE;
if (pfn == KVM_PFN_ERR_HWPOISON) {
kvm_send_hwpoison_signal(kvm_vcpu_gfn_to_hva(vcpu, gfn),
current);
return RET_PF_RETRY;
}
/* KVM_PFN_ERR_FAULT */
return -EFAULT;
Maybe it should return RET_PF_EMULATE, which would cause an emulation
failure and then an exit with KVM_EXIT_INTERNAL_ERROR.
So the root cause is that a running vCPU accessing the memory whose memslot
is being updated (met the condition KVM_MEMSLOT_INVALID is set on the its
memslot).
The normal #PF handler breaks KVM_RUN and returns -EFAULT to userspace, we'd
better to make ept-misconfig's handler follow this style as well.
Actually, the WARN_ON in ept-misconfig's handler is unnecessary as
kvm_mmu_page_fault() will warn us if it is the real ept misconfig, so we can
simply return kvm_mmu_page_fault().
