linux-kernel - Re: [PATCH v5 5/9] x86/paravirt: Add _safe to the read_msr and write

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Date:	Sun, 3 Apr 2016 06:23:36 -0700
From:	Andy Lutomirski <luto@...capital.net>
To:	Borislav Petkov <bp@...en8.de>
Cc:	Andy Lutomirski <luto@...nel.org>, X86 ML <x86@...nel.org>,
	Paolo Bonzini <pbonzini@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	KVM list <kvm@...r.kernel.org>,
	Arjan van de Ven <arjan@...ux.intel.com>,
	xen-devel <Xen-devel@...ts.xen.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH v5 5/9] x86/paravirt: Add _safe to the read_msr and
 write_msr PV hooks

On Sun, Apr 3, 2016 at 1:41 AM, Borislav Petkov <bp@...en8.de> wrote:
> On Sat, Apr 02, 2016 at 07:01:36AM -0700, Andy Lutomirski wrote:
>> These hooks match the _safe variants, so name them accordingly.
>> This will make room for unsafe PV hooks.
>>
>> Signed-off-by: Andy Lutomirski <luto@...nel.org>
>> ---
>>  arch/x86/include/asm/paravirt.h       | 33 +++++++++++++++++----------------
>>  arch/x86/include/asm/paravirt_types.h |  8 ++++----
>>  arch/x86/kernel/paravirt.c            |  4 ++--
>>  arch/x86/xen/enlighten.c              |  4 ++--
>>  4 files changed, 25 insertions(+), 24 deletions(-)
>
> ...
>
>> diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h
>> index 77db5616a473..5a06cccd36f0 100644
>> --- a/arch/x86/include/asm/paravirt_types.h
>> +++ b/arch/x86/include/asm/paravirt_types.h
>> @@ -155,10 +155,10 @@ struct pv_cpu_ops {
>>       void (*cpuid)(unsigned int *eax, unsigned int *ebx,
>>                     unsigned int *ecx, unsigned int *edx);
>>
>> -     /* MSR, PMC and TSR operations.
>> -        err = 0/-EFAULT.  wrmsr returns 0/-EFAULT. */
>> -     u64 (*read_msr)(unsigned int msr, int *err);
>> -     int (*write_msr)(unsigned int msr, unsigned low, unsigned high);
>> +     /* MSR operations.
>> +        err = 0/-EIO.  wrmsr returns 0/-EIO. */
>
> Please reformat this comment properly, while you're at it:
>
>         /*
>          * A sentence.
>          * Another sentence.
>          */

You already caught that one.  It's fixed in "x86/paravirt: Add
paravirt_{read,write}_msr".

Congrats on being deterministic :)

--Andy