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From: "David P. Reed" <dpreed@deepplum.com>
To: "Sean Christopherson" <sean.j.christopherson@intel.com>
Cc: "Andy Lutomirski" <luto@amacapital.net>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Ingo Molnar" <mingo@redhat.com>,
	"Borislav Petkov" <bp@alien8.de>, "X86 ML" <x86@kernel.org>,
	"H. Peter Anvin" <hpa@zytor.com>,
	"Allison Randal" <allison@lohutok.net>,
	"Enrico Weigelt" <info@metux.net>,
	"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	"Kate Stewart" <kstewart@linuxfoundation.org>,
	"Peter Zijlstra (Intel)" <peterz@infradead.org>,
	"Randy Dunlap" <rdunlap@infradead.org>,
	"Martin Molnar" <martin.molnar.programming@gmail.com>,
	"Andy Lutomirski" <luto@kernel.org>,
	"Alexandre Chartre" <alexandre.chartre@oracle.com>,
	"Jann Horn" <jannh@google.com>,
	"Dave Hansen" <dave.hansen@linux.intel.com>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2] Fix undefined operation VMXOFF during reboot and crash
Date: Mon, 29 Jun 2020 18:46:41 -0400 (EDT)
Message-ID: <1593470801.608531492@apps.rackspace.com> (raw)
In-Reply-To: <20200629214956.GA12962@linux.intel.com>



On Monday, June 29, 2020 5:49pm, "Sean Christopherson" <sean.j.christopherson@intel.com> said:

> On Mon, Jun 29, 2020 at 02:22:45PM -0700, Andy Lutomirski wrote:
>>
>>
>> > On Jun 29, 2020, at 1:54 PM, David P. Reed <dpreed@deepplum.com> wrote:
>> >
>> > Simple question for those on the To: and CC: list here. Should I
>> > abandon any hope of this patch being accepted? It's been a long time.
>> >
>> > The non-response after I acknowledged that this was discovered by when
>> > working on a personal, non-commercial research project - which is
>> > "out-of-tree" (apparently dirty words on LKML) has me thinking my
>> > contribution is unwanted. That's fine, I suppose. I can maintain this patch
>> > out-of-tree as well.  I did incorporate all the helpful suggestions I
>> > received in this second patch, and given some encouragement, will happily
>> > submit a revised v3 if there is any likelihood of acceptance. I'm wary of
>> > doing more radical changes (like combining emergency and normal paths).
>> >
>>
>> Sorry about being slow and less actively encouraging than we should be. We
>> absolutely welcome personal contributions. The actual problem is that
>> everyone is worked and we’re all slow. Also, you may be hitting a corner
>> case
>> in the process: is this a KVM patch or an x86 patch?
> 
> It's an x86 patch as it's not KVM specific, e.g. this code also helps play
> nice with out of tree hypervisors.
> 
> The code change is mostly good, but it needs to be split up as there are
> three separate fixes:
> 
>   1. Handle #UD on VMXON due to a race.
>   2. Mark memory and flags as clobbered by VMXON.
>   3. Change emergency_vmx_disable_all() to not manually check cpu_vmx_enabled().
> 
> Yes, the changes are tiny, but if for example #3 introduces a bug then we
> don't have to revert #1 and #2.  Or perhaps older kernels are only subject
> to the #1 and #2 and thus dumping all three changes into a single patch makes
> it all harder to backport.  In other words, all the usual "one change per
> patch" reasons.
> 
Thanks. If no one else responds with additional suggestions, I will make it into 3 patches.
I'm happy to learn the nuances of the kernel patch regimen.




  reply index

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-25 14:45 David P. Reed
2020-06-25 14:59 ` David P. Reed
2020-06-29 20:54   ` David P. Reed
2020-06-29 21:22     ` Andy Lutomirski
2020-06-29 21:49       ` Sean Christopherson
2020-06-29 22:46         ` David P. Reed [this message]
2020-07-04 20:38         ` [PATCH v3 0/3] " David P. Reed
2020-07-04 20:38           ` [PATCH v3 1/3] Correct asm VMXOFF side effects David P. Reed
2020-07-05  5:46             ` Randy Dunlap
2020-07-04 20:38           ` [PATCH v3 2/3] Fix undefined operation fault that can hang a cpu on crash or panic David P. Reed
2020-07-05 18:22             ` Andy Lutomirski
2020-07-05 19:52               ` David P. Reed
2020-07-05 20:55                 ` Andy Lutomirski
2020-07-05 22:07                   ` David P. Reed
2020-07-07  5:09             ` Sean Christopherson
2020-07-07 19:09               ` David P. Reed
2020-07-07 19:24                 ` Sean Christopherson
2020-07-07 19:52                   ` David P. Reed
2020-07-04 20:38           ` [PATCH v3 3/3] Force all cpus to exit VMX root operation on crash/panic reliably David P. Reed
2020-07-05 18:26             ` Andy Lutomirski
2020-07-05 20:00               ` David P. Reed
2020-07-05 20:53                 ` Andy Lutomirski
2020-07-07  5:29                   ` Sean Christopherson
  -- strict thread matches above, loose matches on Subject: below --
2020-06-11 17:02 [PATCH] Fix undefined operation VMXOFF during reboot and crash Andy Lutomirski
2020-06-11 19:45 ` [PATCH v2] " David P. Reed
2020-06-11 19:48 ` David P. Reed
2020-06-25  6:06   ` Sean Christopherson

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