From: Paolo Bonzini <pbonzini@redhat.com>
To: Sean Christopherson <seanjc@google.com>,
Oliver Upton <oupton@google.com>
Cc: kvm@vger.kernel.org, Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
David Dunn <daviddunn@google.com>
Subject: Re: [PATCH v4 1/8] KVM: nVMX: Keep KVM updates to BNDCFGS ctrl bits across MSR write
Date: Thu, 3 Mar 2022 07:29:28 +0100 [thread overview]
Message-ID: <78abcc19-0a79-4f8b-2eaf-c99b96efea42@redhat.com> (raw)
In-Reply-To: <YiAdU+pA/RNeyjRi@google.com>
On 3/3/22 02:43, Sean Christopherson wrote:
>> Maybe I can redirect you to a test case to highlight a possible
>> regression in KVM, as seen by userspace;-)
> Regressions aside, VMCS controls are not tied to CPUID, KVM should not be mucking
> with unrelated things. The original hack was to fix a userspace bug and should
> never have been mreged.
Note that it dates back to:
commit 5f76f6f5ff96587af5acd5930f7d9fea81e0d1a8
Author: Liran Alon <liran.alon@oracle.com>
Date: Fri Sep 14 03:25:52 2018 +0300
KVM: nVMX: Do not expose MPX VMX controls when guest MPX disabled
Before this commit, KVM exposes MPX VMX controls to L1 guest only based
on if KVM and host processor supports MPX virtualization.
However, these controls should be exposed to guest only in case guest
vCPU supports MPX.
It's not to fix a userspace bug, it's to support userspace that doesn't
know about using KVM_SET_MSR for VMX features---which is okay since unlike
KVM_SET_CPUID2 it's not a mandatory call.
Paolo
next prev parent reply other threads:[~2022-03-03 6:29 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-01 6:03 [PATCH v4 0/8] KVM: x86: VMX ctrl MSR + KVM quirk fixes Oliver Upton
2022-03-01 6:03 ` [PATCH v4 1/8] KVM: nVMX: Keep KVM updates to BNDCFGS ctrl bits across MSR write Oliver Upton
2022-03-01 18:00 ` Paolo Bonzini
2022-03-01 18:43 ` Oliver Upton
2022-03-02 12:21 ` Paolo Bonzini
2022-03-02 20:51 ` Oliver Upton
2022-03-02 21:22 ` Paolo Bonzini
2022-03-02 21:54 ` Oliver Upton
2022-03-03 1:43 ` Sean Christopherson
2022-03-03 6:29 ` Paolo Bonzini [this message]
2022-03-03 16:15 ` Sean Christopherson
2022-03-03 21:44 ` Jim Mattson
2022-03-03 23:44 ` Sean Christopherson
2022-03-04 15:50 ` Paolo Bonzini
2022-04-07 0:26 ` Sean Christopherson
2022-04-07 0:29 ` Oliver Upton
2022-04-07 0:32 ` Oliver Upton
2022-04-07 0:34 ` Sean Christopherson
2022-05-27 16:55 ` Sean Christopherson
2022-03-01 6:03 ` [PATCH v4 2/8] KVM: nVMX: Keep KVM updates to PERF_GLOBAL_CTRL " Oliver Upton
2022-03-01 18:01 ` Paolo Bonzini
2022-04-07 0:21 ` Sean Christopherson
2022-03-01 6:03 ` [PATCH v4 3/8] KVM: nVMX: Drop nested_vmx_pmu_refresh() Oliver Upton
2022-03-01 6:03 ` [PATCH v4 4/8] KVM: x86: Introduce KVM_CAP_DISABLE_QUIRKS2 Oliver Upton
2022-03-09 16:01 ` Paolo Bonzini
2022-03-01 6:03 ` [PATCH v4 5/8] KVM: nVMX: Add a quirk for KVM tweaks to VMX control MSRs Oliver Upton
2022-04-07 0:28 ` Sean Christopherson
2022-03-01 6:03 ` [PATCH v4 6/8] selftests: KVM: Separate static alloc from KVM_GET_SUPPORTED_CPUID call Oliver Upton
2022-03-01 6:03 ` [PATCH v4 7/8] selftests: KVM: Add test for PERF_GLOBAL_CTRL VMX control MSR bits Oliver Upton
2022-03-01 16:59 ` David Dunn
2022-03-01 6:03 ` [PATCH v4 8/8] selftests: KVM: Add test for BNDCFGS " Oliver Upton
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=78abcc19-0a79-4f8b-2eaf-c99b96efea42@redhat.com \
--to=pbonzini@redhat.com \
--cc=daviddunn@google.com \
--cc=jmattson@google.com \
--cc=joro@8bytes.org \
--cc=kvm@vger.kernel.org \
--cc=oupton@google.com \
--cc=seanjc@google.com \
--cc=vkuznets@redhat.com \
--cc=wanpengli@tencent.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.