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From: Roman Bolshakov <r.bolshakov@yadro.com>
To: Richard Henderson <richard.henderson@linaro.org>
Cc: Peter Maydell <peter.maydell@linaro.org>,
	QEMU Developers <qemu-devel@nongnu.org>,
	Cameron Esfahani <dirty@apple.com>,
	John Arbuckle <programmingkidx@gmail.com>,
	Hill Ma <maahiuzeon@gmail.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Richard Henderson <rth@twiddle.net>
Subject: Re: [PATCH] hvf: guard xgetbv call.
Date: Tue, 12 Jan 2021 10:49:07 +0300	[thread overview]
Message-ID: <X/1Uc7Ohb+lqEFsU@SPB-NB-133.local> (raw)
In-Reply-To: <259b9e96-1f69-4e4a-16ef-7034e19ed1ef@linaro.org>

On Mon, Jan 11, 2021 at 07:06:22AM -1000, Richard Henderson wrote:
> On 1/10/21 6:31 PM, Roman Bolshakov wrote:
> >> Also, if we're going to put this some place common, forcing the caller to do
> >> the cpuid that feeds this, then we should probably make all of the startup
> >> cpuid stuff common as well.
> >>
> > 
> > I proposed the version because all callers of xgetbv instruction already
> > call cpuid before invoking inline xgetbv.
> > 
> >> Note that we'd probably have to use constructor priorities to get that right
> >> for util/bufferiszero.c.
> >>
> > 
> > Please correct me if I read this wrong. What you're saying is we should
> > initialize cpuid in constructors and then use cached cpuid ecx in
> > xgetbv() (and drop one argument, respectively)?
> 
> I would have xgetbv and all of the cpuid values cached at startup, and all
> three places would read global variables.
> 

It makes sense, thanks for the clarification.

Do you think it should be part of the change Hill is doing or it might
be a follow-up cleanup patch?

-Roman


  reply	other threads:[~2021-01-12  7:53 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-19  2:13 [PATCH] hvf: guard xgetbv call Hill Ma
2021-01-09  5:48 ` Roman Bolshakov
2021-01-09 11:42   ` Peter Maydell
2021-01-10  1:46     ` Roman Bolshakov
2021-01-10 18:34       ` Richard Henderson
2021-01-10 18:38         ` Richard Henderson
2021-01-11  4:31           ` Roman Bolshakov
2021-01-11 17:06             ` Richard Henderson
2021-01-12  7:49               ` Roman Bolshakov [this message]
2021-01-12 15:28                 ` Richard Henderson

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