On 21.07.19 13:57, Liran Alon wrote: > > >> On 21 Jul 2019, at 14:52, Jan Kiszka <jan.kiszka@xxxxxx> wrote: >> >> From: Jan Kiszka <jan.kiszka@xxxxxxxxxxx> >> >> Letting this pend may cause nested_get_vmcs12_pages to run against an >> invalid state, corrupting the effective vmcs of L1. >> >> This was triggerable in QEMU after a guest corruption in L2, followed by >> a L1 reset. >> >> Signed-off-by: Jan Kiszka <jan.kiszka@xxxxxxxxxxx> > > Good catch. > Reviewed-by: Liran Alon <liran.alon@xxxxxxxxxx> > > This would have been more easily diagnosed in case free_nested() would NULL cached_vmcs12 and cached_shadow_vmcs12 > after kfree() and add to get_vmcs12() & get_shadow_vmcs12() a relevant BUG_ON() call. The NULL'ifying makes sense, patch follows. But the helpers are too often called unconditionally, thus cause false positives when adding the BUG_ON. Jan > > I would submit such a patch separately. > > -Liran > >> --- >> >> And another gremlin. I'm afraid there is at least one more because >> vmport access from L2 is still failing in QEMU. This is just another >> fallout from that. At least the host seems stable now. >> >> arch/x86/kvm/vmx/nested.c | 2 ++ >> 1 file changed, 2 insertions(+) >> >> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c >> index 0f1378789bd0..4cdab4b4eff1 100644 >> --- a/arch/x86/kvm/vmx/nested.c >> +++ b/arch/x86/kvm/vmx/nested.c >> @@ -220,6 +220,8 @@ static void free_nested(struct kvm_vcpu *vcpu) >> if (!vmx->nested.vmxon && !vmx->nested.smm.vmxon) >> return; >> >> + kvm_clear_request(KVM_REQ_GET_VMCS12_PAGES, vcpu); >> + >> vmx->nested.vmxon = false; >> vmx->nested.smm.vmxon = false; >> free_vpid(vmx->nested.vpid02); >> -- >> 2.16.4
