From: Andy Lutomirski <luto@amacapital.net>
To: Andi Kleen <ak@linux.intel.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Lai Jiangshan <jiangshanlai+lkml@gmail.com>,
Sean Christopherson <sean.j.christopherson@intel.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
kvm@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Uros Bizjak <ubizjak@gmail.com>,
Andy Lutomirski <luto@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [PATCH v2 2/2] KVM: VMX: Invoke NMI handler via indirect call instead of INTn
Date: Mon, 26 Apr 2021 08:09:46 -0700 [thread overview]
Message-ID: <E67D7461-68B3-44E5-ADB5-52E5A4D3897D@amacapital.net> (raw)
In-Reply-To: <20210426145104.GW1401198@tassilo.jf.intel.com>
> On Apr 26, 2021, at 7:51 AM, Andi Kleen <ak@linux.intel.com> wrote:
>
>
>>
>>> The original code "int $2" can provide the needed CPU-hidden-NMI-masked
>>> when entering #NMI, but I doubt it about this change.
>>
>> How would "int $2" block NMIs? The hidden effect of this change (and I
>> should have reviewed better the effect on the NMI entry code) is that the
>> call will not use the IST anymore.
>
> My understanding is that int $2 does not block NMIs.
>
> So reentries might have been possible.
>
The C NMI code has its own reentrancy protection and has for years. It should work fine for this use case.
> -Andi
next prev parent reply other threads:[~2021-04-26 15:09 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-15 19:15 [PATCH v2 0/2] KVM: VMX: Clean up IRQ/NMI handling Sean Christopherson
2020-09-15 19:15 ` [PATCH v2 1/2] KVM: VMX: Move IRQ invocation to assembly subroutine Sean Christopherson
2020-09-15 19:27 ` Josh Poimboeuf
2020-09-15 19:38 ` Uros Bizjak
2020-09-15 19:15 ` [PATCH v2 2/2] KVM: VMX: Invoke NMI handler via indirect call instead of INTn Sean Christopherson
2021-04-26 9:33 ` Lai Jiangshan
2021-04-26 10:40 ` Paolo Bonzini
2021-04-26 11:44 ` Maxim Levitsky
2021-04-26 13:59 ` Steven Rostedt
2021-04-26 14:51 ` Andi Kleen
2021-04-26 15:09 ` Andy Lutomirski [this message]
2021-04-27 0:54 ` Lai Jiangshan
2021-04-27 1:00 ` Steven Rostedt
2021-04-27 7:05 ` Paolo Bonzini
2021-04-30 2:56 ` Lai Jiangshan
2020-09-22 13:38 ` [PATCH v2 0/2] KVM: VMX: Clean up IRQ/NMI handling Paolo Bonzini
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=E67D7461-68B3-44E5-ADB5-52E5A4D3897D@amacapital.net \
--to=luto@amacapital.net \
--cc=ak@linux.intel.com \
--cc=jiangshanlai+lkml@gmail.com \
--cc=jmattson@google.com \
--cc=joro@8bytes.org \
--cc=jpoimboe@redhat.com \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=luto@kernel.org \
--cc=pbonzini@redhat.com \
--cc=rostedt@goodmis.org \
--cc=sean.j.christopherson@intel.com \
--cc=ubizjak@gmail.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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).