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From: Borislav Petkov <bp@suse.de>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Linux Virtualization <virtualization@lists.linux-foundation.org>,
	Ingo Molnar <mingo@redhat.com>,
	David Vrabel <david.vrabel@citrix.com>,
	Andrew Lutomirski <luto@kernel.org>,
	"H. Peter Anvin" <hpa@zytor.com>,
	"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>,
	Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH 1/3] x86/xen: Avoid fast syscall path for Xen PV guests
Date: Thu, 19 Nov 2015 13:08:09 +0100	[thread overview]
Message-ID: <20151119120809.GC5953@pd.tnic> (raw)
In-Reply-To: <CALCETrVUpqQy_EZMe8T5iRkA0FzS0Oz1Kuicr9yz3SwtdF1=9g@mail.gmail.com>

On Wed, Nov 18, 2015 at 12:21:56PM -0800, Andy Lutomirski wrote:
> Could we make this a little less subtle:
> 
> ALTERNATIVE "testl %eax, %eax; lz .Lsyscall_32_done", "jmp
> .Lsyscasll_32_done", X86_FEATURE_XENPV
> 
> Borislav, what do you think?

I don't mind either.

I would've said your version doesn't touch %eax so the result in there
might be useful for callers but all paths do overwrite it, AFAICT.

-- 
Regards/Gruss,
    Boris.

SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
-- 
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  parent reply	other threads:[~2015-11-19 12:08 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <1447877179-2775-1-git-send-email-boris.ostrovsky@oracle.com>
2015-11-18 20:06 ` [PATCH 1/3] x86/xen: Avoid fast syscall path for Xen PV guests Boris Ostrovsky
2015-11-18 20:06 ` [PATCH 2/3] x86: irq_enable_sysexit pv op is no longer needed Boris Ostrovsky
2015-11-18 20:06 ` [PATCH 3/3] x86: usergs_sysret32 " Boris Ostrovsky
     [not found] ` <1447877179-2775-2-git-send-email-boris.ostrovsky@oracle.com>
2015-11-18 20:21   ` [PATCH 1/3] x86/xen: Avoid fast syscall path for Xen PV guests Andy Lutomirski
2015-11-18 20:47     ` Borislav Petkov
2015-11-18 20:50     ` Brian Gerst
     [not found]     ` <CAMzpN2iofkEeYkiZa8FRJ5gbz5smPbV0COOye9wZ9OhV6pBfow@mail.gmail.com>
2015-11-18 20:58       ` Andy Lutomirski
2015-11-18 22:05         ` Boris Ostrovsky
2015-11-19 12:08     ` Borislav Petkov [this message]
     [not found] ` <1447877179-2775-3-git-send-email-boris.ostrovsky@oracle.com>
2015-11-18 20:23   ` [PATCH 2/3] x86: irq_enable_sysexit pv op is no longer needed Andy Lutomirski
     [not found]   ` <20151118201152.GA6094@char.us.oracle.com>
2015-11-18 20:34     ` Boris Ostrovsky
     [not found] ` <1447877179-2775-4-git-send-email-boris.ostrovsky@oracle.com>
2015-11-18 20:26   ` [PATCH 3/3] x86: usergs_sysret32 " Andy Lutomirski
2015-11-19 12:10 ` [PATCH 0/3] Fix and cleanup for 32-bit PV sysexit Borislav Petkov

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