From: Sean Christopherson <seanjc@google.com>
To: Maxim Levitsky <mlevitsk@redhat.com>
Cc: kvm@vger.kernel.org, Paolo Bonzini <pbonzini@redhat.com>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
linux-kernel@vger.kernel.org,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Sandipan Das <sandipan.das@amd.com>,
Daniel Sneddon <daniel.sneddon@linux.intel.com>,
Jing Liu <jing2.liu@intel.com>,
Josh Poimboeuf <jpoimboe@kernel.org>,
Wyes Karny <wyes.karny@amd.com>, Borislav Petkov <bp@alien8.de>,
Babu Moger <babu.moger@amd.com>,
Pawan Gupta <pawan.kumar.gupta@linux.intel.com>,
Jim Mattson <jmattson@google.com>,
x86@kernel.org
Subject: Re: [PATCH 02/13] KVM: nSVM: don't call nested_sync_control_from_vmcb02 on each VM exit
Date: Thu, 17 Nov 2022 20:04:54 +0000 [thread overview]
Message-ID: <Y3aT5qBgOuwsOeS/@google.com> (raw)
In-Reply-To: <20221117143242.102721-3-mlevitsk@redhat.com>
On Thu, Nov 17, 2022, Maxim Levitsky wrote:
> Calling nested_sync_control_from_vmcb02 on each VM exit (nested or not),
> was an attempt to keep the int_ctl field in the vmcb12 cache
> up to date on each VM exit.
This doesn't mesh with the reasoning in commit 2d8a42be0e2b ("KVM: nSVM: synchronize
VMCB controls updated by the processor on every vmexit"), which states that the
goal is to keep svm->nested.ctl.* synchronized, not vmcb12. Or is nested.ctl the
cache you are referring to?
> However all other fields in the vmcb12 cache are not kept up to date,
IIUC, this isn't technically true. They are up-to-date because they're never
modified by hardware.
> therefore for consistency it is better to do this on a nested VM exit only.
Again, IIUC, this actually introduces an inconsistency because it leaves stale
state in svm->nested.ctl, whereas the existing code ensures all state in
svm->nested.ctl is fresh immediately after non-nested VM-Exit.
next prev parent reply other threads:[~2022-11-17 20:05 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-17 14:32 [PATCH 00/13] SVM: vNMI (with my fixes) Maxim Levitsky
2022-11-17 14:32 ` [PATCH 01/13] KVM: nSVM: don't sync back tlb_ctl on nested VM exit Maxim Levitsky
2022-11-17 14:32 ` [PATCH 02/13] KVM: nSVM: don't call nested_sync_control_from_vmcb02 on each " Maxim Levitsky
2022-11-17 20:04 ` Sean Christopherson [this message]
2022-11-21 11:07 ` Maxim Levitsky
2022-11-21 17:51 ` Sean Christopherson
2022-11-17 14:32 ` [PATCH 03/13] KVM: nSVM: rename nested_sync_control_from_vmcb02 to nested_sync_int_ctl_from_vmcb02 Maxim Levitsky
2022-11-17 14:32 ` [PATCH 04/13] KVM: nSVM: clean up copying of int_ctl fields back to vmcb01/vmcb12 Maxim Levitsky
2022-11-17 20:15 ` Sean Christopherson
2022-11-21 11:10 ` Maxim Levitsky
2022-11-17 14:32 ` [PATCH 05/13] x86/cpu: Add CPUID feature bit for VNMI Maxim Levitsky
2022-11-17 14:32 ` [PATCH 06/13] KVM: SVM: Add VNMI bit definition Maxim Levitsky
2022-11-17 14:37 ` Borislav Petkov
2022-11-17 16:42 ` Sean Christopherson
2022-11-17 17:07 ` Borislav Petkov
2022-11-17 20:33 ` Sean Christopherson
2022-11-17 20:27 ` Sean Christopherson
2022-11-17 14:32 ` [PATCH 07/13] KVM: SVM: Add VNMI support in get/set_nmi_mask Maxim Levitsky
2022-11-17 18:54 ` Sean Christopherson
2022-11-21 12:36 ` Maxim Levitsky
2022-11-21 17:18 ` Sean Christopherson
2022-12-04 18:42 ` Maxim Levitsky
2022-12-06 18:27 ` Sean Christopherson
2022-11-17 14:32 ` [PATCH 08/13] KVM: SVM: Report NMI not allowed when Guest busy handling VNMI Maxim Levitsky
2022-11-17 14:32 ` [PATCH 09/13] KVM: SVM: allow NMI window with vNMI Maxim Levitsky
2022-11-17 18:21 ` Sean Christopherson
2022-11-21 13:40 ` Maxim Levitsky
2022-11-17 14:32 ` [PATCH 10/13] KVM: SVM: Add VNMI support in inject_nmi Maxim Levitsky
2022-11-21 17:12 ` Sean Christopherson
2022-11-17 14:32 ` [PATCH 11/13] KVM: nSVM: implement nested VNMI Maxim Levitsky
2022-11-17 14:32 ` [PATCH 12/13] KVM: nSVM: emulate VMEXIT_INVALID case for " Maxim Levitsky
2022-11-17 20:18 ` Sean Christopherson
2022-11-17 14:32 ` [PATCH 13/13] KVM: SVM: Enable VNMI feature Maxim Levitsky
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=Y3aT5qBgOuwsOeS/@google.com \
--to=seanjc@google.com \
--cc=babu.moger@amd.com \
--cc=bp@alien8.de \
--cc=daniel.sneddon@linux.intel.com \
--cc=dave.hansen@linux.intel.com \
--cc=hpa@zytor.com \
--cc=jing2.liu@intel.com \
--cc=jmattson@google.com \
--cc=jpoimboe@kernel.org \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=mlevitsk@redhat.com \
--cc=pawan.kumar.gupta@linux.intel.com \
--cc=pbonzini@redhat.com \
--cc=peterz@infradead.org \
--cc=sandipan.das@amd.com \
--cc=tglx@linutronix.de \
--cc=wyes.karny@amd.com \
--cc=x86@kernel.org \
/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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox