From: "H. Peter Anvin" <hpa@zytor.com>
To: Sean Christopherson <seanjc@google.com>
Cc: Sohil Mehta <sohil.mehta@intel.com>, Xin Li <xin@zytor.com>,
x86@kernel.org, linux-kernel@vger.kernel.org,
Andy Lutomirski <luto@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
Peter Zijlstra <peterz@infradead.org>,
Adrian Hunter <adrian.hunter@intel.com>,
Kan Liang <kan.liang@linux.intel.com>,
Tony Luck <tony.luck@intel.com>, Zhang Rui <rui.zhang@intel.com>,
Steven Rostedt <rostedt@goodmis.org>,
Andrew Cooper <andrew.cooper3@citrix.com>,
"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
Jacob Pan <jacob.pan@linux.microsoft.com>,
Andi Kleen <ak@linux.intel.com>, Kai Huang <kai.huang@intel.com>,
Sandipan Das <sandipan.das@amd.com>,
linux-perf-users@vger.kernel.org, linux-edac@vger.kernel.org,
kvm@vger.kernel.org, linux-pm@vger.kernel.org,
linux-trace-kernel@vger.kernel.org
Subject: Re: [PATCH v7 02/10] x86/fred: Pass event data to the NMI entry point from KVM
Date: Fri, 20 Jun 2025 16:22:12 -0700 [thread overview]
Message-ID: <1713a225-44e0-4018-bf5f-64ffd7746167@zytor.com> (raw)
In-Reply-To: <aFXsPVIKi6wFUB6x@google.com>
On 2025-06-20 16:18, Sean Christopherson wrote:
>>
>> So I was thinking about this, and wonder: how expensive is it to get the
>> event data exit information out of VMX? If it is not very expensive, it
>> would arguably be a good thing to future-proof by fetching that information,
>> even if it is currently always zero.
>
> It's trivially easy to do in KVM, and the cost of the VMREAD should be less than
> 20 cycles. So quite cheap in the grand scheme. If VMREAD is more costly than
> that, then we have bigger problems :-)
>
LOL. Since it is up to you, Paulo, etc. to decide how to do the
tradeoffs formaintainability, debuggability and performance in KVM I am
guessing this is a vote in favor? (You can always take it out if it is a
performance problem, until such time that the kernel itself starts
consuming this information for reasons currently unknown.)
-hpa
next prev parent reply other threads:[~2025-06-20 23:22 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-06-12 21:48 [PATCH v7 00/10] x86: Add support for NMI-source reporting with FRED Sohil Mehta
2025-06-12 21:48 ` [PATCH v7 01/10] x86/fred: Provide separate IRQ vs. NMI wrappers for entry from KVM Sohil Mehta
2025-06-19 3:53 ` Xin Li
2025-06-19 21:35 ` Sohil Mehta
2025-06-12 21:48 ` [PATCH v7 02/10] x86/fred: Pass event data to the NMI entry point " Sohil Mehta
2025-06-13 0:18 ` Sean Christopherson
2025-06-13 15:20 ` Sohil Mehta
2025-06-19 5:02 ` Xin Li
2025-06-19 22:15 ` Sohil Mehta
2025-06-19 22:45 ` Xin Li
2025-06-19 22:57 ` Sohil Mehta
2025-06-20 22:51 ` H. Peter Anvin
2025-06-20 23:18 ` Sean Christopherson
2025-06-20 23:22 ` H. Peter Anvin [this message]
2025-06-23 15:39 ` Sean Christopherson
2025-06-23 16:10 ` H. Peter Anvin
2025-06-12 21:48 ` [PATCH v7 03/10] x86/cpufeatures: Add the CPUID feature bit for NMI-source reporting Sohil Mehta
2025-06-19 5:06 ` Xin Li
2025-06-12 21:48 ` [PATCH v7 04/10] x86/nmi: Extend the registration interface to include the NMI-source vector Sohil Mehta
2025-06-12 21:48 ` [PATCH v7 05/10] x86/nmi: Assign and register NMI-source vectors Sohil Mehta
2025-07-07 13:21 ` Zhuo, Qiuxu
2025-07-07 20:00 ` Sohil Mehta
2025-07-08 7:30 ` Zhuo, Qiuxu
2025-07-11 0:32 ` Sohil Mehta
2025-06-12 21:48 ` [PATCH v7 06/10] x86/nmi: Add support to handle NMIs with source information Sohil Mehta
2025-07-07 13:50 ` Zhuo, Qiuxu
2025-07-07 20:32 ` Sohil Mehta
2025-06-12 21:48 ` [PATCH v7 07/10] x86/nmi: Prepare for the new NMI-source vector encoding Sohil Mehta
2025-06-19 7:43 ` Chao Gao
2025-06-19 22:23 ` Sohil Mehta
2025-06-19 22:54 ` Sohil Mehta
2025-06-12 21:48 ` [PATCH v7 08/10] x86/nmi: Enable NMI-source for IPIs delivered as NMIs Sohil Mehta
2025-07-08 18:37 ` Sean Christopherson
2025-07-10 22:04 ` Sohil Mehta
2025-07-10 22:40 ` Sean Christopherson
2025-07-24 22:59 ` Sohil Mehta
2025-06-12 21:48 ` [PATCH v7 09/10] perf/x86: Enable NMI-source reporting for perfmon Sohil Mehta
2025-06-12 21:48 ` [PATCH v7 10/10] x86/nmi: Print source information with the unknown NMI console message Sohil Mehta
2025-06-13 7:06 ` [PATCH v7 00/10] x86: Add support for NMI-source reporting with FRED Peter Zijlstra
2025-06-13 15:21 ` Sohil Mehta
2025-07-07 13:56 ` Zhuo, Qiuxu
2025-07-07 20:33 ` Sohil Mehta
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=1713a225-44e0-4018-bf5f-64ffd7746167@zytor.com \
--to=hpa@zytor.com \
--cc=adrian.hunter@intel.com \
--cc=ak@linux.intel.com \
--cc=andrew.cooper3@citrix.com \
--cc=bp@alien8.de \
--cc=dave.hansen@linux.intel.com \
--cc=jacob.pan@linux.microsoft.com \
--cc=kai.huang@intel.com \
--cc=kan.liang@linux.intel.com \
--cc=kirill.shutemov@linux.intel.com \
--cc=kvm@vger.kernel.org \
--cc=linux-edac@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-perf-users@vger.kernel.org \
--cc=linux-pm@vger.kernel.org \
--cc=linux-trace-kernel@vger.kernel.org \
--cc=luto@kernel.org \
--cc=mingo@redhat.com \
--cc=peterz@infradead.org \
--cc=rostedt@goodmis.org \
--cc=rui.zhang@intel.com \
--cc=sandipan.das@amd.com \
--cc=seanjc@google.com \
--cc=sohil.mehta@intel.com \
--cc=tglx@linutronix.de \
--cc=tony.luck@intel.com \
--cc=x86@kernel.org \
--cc=xin@zytor.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).