From: Paolo Bonzini <pbonzini@redhat.com> To: Sean Christopherson <sean.j.christopherson@intel.com> Cc: Vitaly Kuznetsov <vkuznets@redhat.com>, kvm@vger.kernel.org, Jim Mattson <jmattson@google.com>, linux-kernel@vger.kernel.org, Liran Alon <liran.alon@oracle.com>, Roman Kagan <rkagan@virtuozzo.com> Subject: Re: [PATCH RFC 2/3] x86/kvm/hyper-v: move VMX controls sanitization out of nested_enable_evmcs() Date: Wed, 22 Jan 2020 15:33:05 +0100 Message-ID: <9c126d75-225b-3b1b-d97a-bcec1f189e02@redhat.com> (raw) In-Reply-To: <20200122054724.GD18513@linux.intel.com> On 22/01/20 06:47, Sean Christopherson wrote: >> Yes, it most likely is and it would be nice if Microsoft fixed it, but I >> guess we're stuck with it for existing Windows versions. Well, for one >> we found a bug in Hyper-V and not the converse. :) >> >> There is a problem with this approach, in that we're stuck with it >> forever due to live migration. But I guess if in the future eVMCS v2 >> adds an apic_address field we can limit the hack to eVMCS v1. Another >> possibility is to use the quirks mechanism but it's overkill for now. >> >> Unless there are objections, I plan to apply these patches. > Doesn't applying this patch contradict your earlier opinion? This patch > would still hide the affected controls from the guest because the host > controls enlightened_vmcs_enabled. It does. Unfortunately the key sentence is "we're stuck with it for existing Windows versions". :( > Rather than update vmx->nested.msrs or filter vmx_get_msr(), what about > manually adding eVMCS consistency checks on the disallowed bits and handle > SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES as a one-off case by simply > clearing it from the eVMCS? Or alternatively, squashing all the disallowed > bits. Hmm, that is also a possibility. It's a very hacky one, but I guess adding APIC virtualization to eVMCS would require bumping the version to 2. Vitaly, what do you think? Paolo
next prev parent reply index Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-01-15 17:10 [PATCH RFC 0/3] x86/kvm/hyper-v: fix enlightened VMCS & QEMU4.2 Vitaly Kuznetsov 2020-01-15 17:10 ` [PATCH RFC 1/3] x86/kvm/hyper-v: remove stale evmcs_already_enabled check from nested_enable_evmcs() Vitaly Kuznetsov 2020-01-15 22:50 ` Liran Alon 2020-01-15 17:10 ` [PATCH RFC 2/3] x86/kvm/hyper-v: move VMX controls sanitization out of nested_enable_evmcs() Vitaly Kuznetsov 2020-01-15 22:49 ` Liran Alon 2020-01-16 8:37 ` Vitaly Kuznetsov 2020-02-03 15:11 ` Vitaly Kuznetsov 2020-01-15 23:27 ` Sean Christopherson 2020-01-15 23:30 ` Liran Alon 2020-01-16 8:51 ` Vitaly Kuznetsov 2020-01-16 16:19 ` Sean Christopherson 2020-01-16 16:57 ` Vitaly Kuznetsov 2020-01-17 6:31 ` Sean Christopherson 2020-01-18 21:42 ` Paolo Bonzini 2020-01-19 8:54 ` Paolo Bonzini 2020-01-22 5:47 ` Sean Christopherson 2020-01-22 9:37 ` Vitaly Kuznetsov 2020-01-22 14:33 ` Paolo Bonzini [this message] 2020-01-22 15:08 ` Vitaly Kuznetsov 2020-01-22 15:51 ` Sean Christopherson 2020-01-22 16:29 ` Vitaly Kuznetsov 2020-01-22 16:40 ` Paolo Bonzini 2020-01-23 9:15 ` Vitaly Kuznetsov 2020-01-23 19:09 ` Vitaly Kuznetsov 2020-01-24 17:25 ` Sean Christopherson 2020-01-27 15:38 ` Vitaly Kuznetsov 2020-01-27 17:53 ` Paolo Bonzini 2020-01-27 21:52 ` Vitaly Kuznetsov 2020-01-27 18:17 ` Sean Christopherson 2020-01-15 17:10 ` [PATCH RFC 3/3] x86/kvm/hyper-v: don't allow to turn on unsupported VMX controls for nested guests Vitaly Kuznetsov 2020-01-15 22:59 ` Liran Alon 2020-01-16 8:55 ` Vitaly Kuznetsov 2020-01-16 16:21 ` Sean Christopherson 2020-01-19 8:57 ` Paolo Bonzini
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