linux-kernel - Re: [PATCH v2 06/12] KVM: MMU: introduce a static table to map guest access to spte access

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 28 Jan 2013 22:07:15 -0200
From:	Marcelo Tosatti <mtosatti@...hat.com>
To:	Xiao Guangrong <xiaoguangrong@...ux.vnet.ibm.com>
Cc:	Avi Kivity <avi.kivity@...il.com>, Gleb Natapov <gleb@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>, KVM <kvm@...r.kernel.org>
Subject: Re: [PATCH v2 06/12] KVM: MMU: introduce a static table to map guest
 access to spte access

On Fri, Jan 25, 2013 at 10:46:31AM +0800, Xiao Guangrong wrote:
> On 01/25/2013 08:15 AM, Marcelo Tosatti wrote:
> > On Wed, Jan 23, 2013 at 06:07:20PM +0800, Xiao Guangrong wrote:
> >> It makes set_spte more clean and reduces branch prediction
> >>
> >> Signed-off-by: Xiao Guangrong <xiaoguangrong@...ux.vnet.ibm.com>
> >> ---
> >>  arch/x86/kvm/mmu.c |   37 ++++++++++++++++++++++++++-----------
> >>  1 files changed, 26 insertions(+), 11 deletions(-)
> > 
> > Don't see set_spte as being a performance problem?
> > IMO the current code is quite simple.
> 
> Yes, this is not a performance problem.
> 
> I just dislike this many continuous "if"-s in the function:
> 
> if (xxx)
> 	xxx
> if (xxx)
> 	xxx
> ....
> 
> Totally, it has 7 "if"-s before this patch.
> 
> Okay, if you think this is unnecessary, i will drop this patch. :)

Yes, please (unless you can show set_spte is a performance problem).


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/