From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vitaly Kuznetsov Subject: Re: [PATCH] KVM: vmx: hyper-v: don't pass EPT configuration info to vmx_hv_remote_flush_tlb() Date: Thu, 11 Oct 2018 14:18:19 +0200 Message-ID: <87zhvkpth0.fsf@vitty.brq.redhat.com> References: <20181011100312.4083-1-vkuznets@redhat.com> Mime-Version: 1.0 Content-Type: text/plain Cc: kvm , Paolo Bonzini , Radim Krcmar , kys@microsoft.com, haiyangz@microsoft.com, sthemmin@microsoft.com, Michael.H.Kelley@microsoft.com, Tianyu Lan , "linux-kernel\@vger kernel org" To: Tianyu Lan Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org Tianyu Lan writes: > On Thu, Oct 11, 2018 at 6:32 PM Vitaly Kuznetsov wrote: >> >> I'm observing random crashes in multi-vCPU L2 guests running on KVM on >> Hyper-V. I bisected the issue to the commit 877ad952be3d ("KVM: vmx: Add >> tlb_remote_flush callback support"). Hyper-V TLFS states: >> >> "AddressSpace specifies an address space ID (an EPT PML4 table pointer)" >> >> So apparently, Hyper-V doesn't expect us to pass naked EPTP, only PML4 >> pointer should be used. Strip off EPT configuration information before >> calling into vmx_hv_remote_flush_tlb(). > > Hi Vitaly: > : Thanks to fix this. Sorry, I didn't meet the issue.. > I think we may just store EPT PML4 table pointer without EPT > configuration information > in the ept_pointer field for this case. > > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > index 619307b3e6bb..e316058b41a6 100644 > --- a/arch/x86/kvm/vmx.c > +++ b/arch/x86/kvm/vmx.c > @@ -5379,7 +5379,7 @@ static void vmx_set_cr3(struct kvm_vcpu *vcpu, > unsigned long cr3) > > if (kvm_x86_ops->tlb_remote_flush) { > spin_lock(&to_kvm_vmx(kvm)->ept_pointer_lock); > - to_vmx(vcpu)->ept_pointer = eptp; > + to_vmx(vcpu)->ept_pointer = cr3; True, we can do that (and I even had a version of my patch doing so) but 'ept_pointer' will likely need to be renamed as it's not obvious why vcpu->ept_pointer != eptp. Alternatively, we can filter lower 12 bits out in hyperv_flush_guest_mapping() but I would rename 'as' parameter to eptp then. [snip] -- Vitaly