From: Marcelo Tosatti <mtosatti@redhat.com>
To: Gleb Natapov <gleb@redhat.com>
Cc: Andrew Honig <ahonig@google.com>, kvm <kvm@vger.kernel.org>,
Eric Northup <digitaleric@google.com>
Subject: Re: KVM: x86: drop alignment checks from KVM_MSR_SYSTEM_TIME address
Date: Thu, 11 Apr 2013 13:05:45 -0300 [thread overview]
Message-ID: <20130411160544.GA20855@amt.cnet> (raw)
In-Reply-To: <20130323141211.GA26995@redhat.com>
On Sat, Mar 23, 2013 at 04:12:11PM +0200, Gleb Natapov wrote:
> On Fri, Mar 22, 2013 at 05:17:38PM -0700, Andrew Honig wrote:
> > kvm_write_guest would work, but it will hurt performance a bit because
> > it'll be doing the address translation each time the time is updated,
> > which happens on most guest enters.
> >
> Time updates are rare, so this should no be an issue. Marcelo?
Yes, performance is not an issue at this level.
> > Another possibility would be to change kvm_gfn_to_hva_cache_init to
> > accept a size parameter. If the requested range is all on one page
> > then it operates the same as it currently does. If the address range
> > is on more than one page then it falls back to kvm_write_guest. This
> > preserves the good performance for all cases that currently work,
> > while still supporting the unlikely case of page straddling requests.
> > It also makes it harder to write a security bugs for other callers of
> > kvm_gfn_to_hva_cache_init by explicitly requiring a size parameter.
> >
> > I can write a patch if you like the idea.
> Nice idea. Send a patch please.
>
prev parent reply other threads:[~2013-04-11 16:05 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-03-22 19:14 KVM: x86: relax MSR_KVM_SYSTEM_TIME alignment check Marcelo Tosatti
2013-03-22 19:21 ` Gleb Natapov
2013-03-22 19:47 ` Marcelo Tosatti
2013-03-22 21:19 ` KVM: x86: drop alignment checks from KVM_MSR_SYSTEM_TIME address Marcelo Tosatti
2013-03-22 21:57 ` Gleb Natapov
2013-03-23 0:17 ` Andrew Honig
2013-03-23 14:12 ` Gleb Natapov
2013-04-11 16:05 ` Marcelo Tosatti [this message]
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