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From: "David P. Reed" <dpreed@deepplum.com>
To: "Andy Lutomirski" <luto@kernel.org>
Cc: "Sean Christopherson" <sean.j.christopherson@intel.com>,
	"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 v3 2/3] Fix undefined operation fault that can hang a cpu on crash or panic
Date: Sun, 5 Jul 2020 15:52:08 -0400 (EDT)
Message-ID: <1593978728.059424180@apps.rackspace.com> (raw)
In-Reply-To: <CALCETrVZx4VA9rg-Hn7KdER866ZOtZtmTkR0MSacnj5jGO-Pag@mail.gmail.com>

Thanks, will handle these. 2 questions below.

On Sunday, July 5, 2020 2:22pm, "Andy Lutomirski" <luto@kernel.org> said:

> On Sat, Jul 4, 2020 at 1:38 PM David P. Reed <dpreed@deepplum.com> wrote:
>>
>> Fix: Mask undefined operation fault during emergency VMXOFF that must be
>> attempted to force cpu exit from VMX root operation.
>> Explanation: When a cpu may be in VMX root operation (only possible when
>> CR4.VMXE is set), crash or panic reboot tries to exit VMX root operation
>> using VMXOFF. This is necessary, because any INIT will be masked while cpu
>> is in VMX root operation, but that state cannot be reliably
>> discerned by the state of the cpu.
>> VMXOFF faults if the cpu is not actually in VMX root operation, signalling
>> undefined operation.
>> Discovered while debugging an out-of-tree x-visor with a race. Can happen
>> due to certain kinds of bugs in KVM.
> 
> Can you re-wrap lines to 68 characters?  Also, the Fix: and

I used 'scripts/checkpatch.pl' and it had me wrap to 75 chars:
"WARNING: Possible unwrapped commit description (prefer a maximum 75 chars per line)"

Should I submit a fix to checkpatch.pl to say 68? 

> Explanation: is probably unnecessary.  You could say:
> 
> Ignore a potential #UD failut during emergency VMXOFF ...
> 
> When a cpu may be in VMX ...
> 
>>
>> Fixes: 208067 <https://bugzilla.kernel.org/show_bug.cgi?id=208067>
>> Reported-by: David P. Reed <dpreed@deepplum.com>
> 
> It's not really necessary to say that you, the author, reported the
> problem, but I guess it's harmless.
> 
>> Suggested-by: Thomas Gleixner <tglx@linutronix.de>
>> Suggested-by: Sean Christopherson <sean.j.christopherson@intel.com>
>> Suggested-by: Andy Lutomirski <luto@kernel.org>
>> Signed-off-by: David P. Reed <dpreed@deepplum.com>
>> ---
>>  arch/x86/include/asm/virtext.h | 20 ++++++++++++++------
>>  1 file changed, 14 insertions(+), 6 deletions(-)
>>
>> diff --git a/arch/x86/include/asm/virtext.h b/arch/x86/include/asm/virtext.h
>> index 0ede8d04535a..0e0900eacb9c 100644
>> --- a/arch/x86/include/asm/virtext.h
>> +++ b/arch/x86/include/asm/virtext.h
>> @@ -30,11 +30,11 @@ static inline int cpu_has_vmx(void)
>>  }
>>
>>
>> -/* Disable VMX on the current CPU
>> +/* Exit VMX root mode and isable VMX on the current CPU.
> 
> s/isable/disable/
> 
> 
>>  /* Disable VMX if it is supported and enabled on the current CPU
>> --
>> 2.26.2
>>
> 
> Other than that:
> 
> Reviewed-by: Andy Lutomirski <luto@kernel.org>

As a newbie, I have a process question - should I resend the patch with the 'Reviewed-by' line, as well as correcting the other wording? Thanks!

> 
> --Andy
> 



  reply index

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-25 14:45 [PATCH v2] Fix undefined operation VMXOFF during reboot and crash 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
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 [this message]
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

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