From: Sasha Levin <levinsasha928@gmail.com>
To: Avi Kivity <avi@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>, kvm@vger.kernel.org
Subject: Re: [PATCH 1/2] KVM: Don't fail KVM_GET_SUPPORTED_CPUID if nent is just right
Date: Thu, 24 Nov 2011 12:37:58 +0200 [thread overview]
Message-ID: <1322131078.4248.15.camel@lappy> (raw)
In-Reply-To: <4ECE1D81.1000702@redhat.com>
On Thu, 2011-11-24 at 12:33 +0200, Avi Kivity wrote:
> On 11/24/2011 12:31 PM, Sasha Levin wrote:
> > >
> > > The protocol goes like "try size x, if it fails with -E2BIG, increase x,
> > > try again". Its awkward.
> >
> > We can set nent to be the amount of entries required like we do in the
> > opposite case where we passed too many entries.
>
> There's no point, since userspace will want to support older kernels.
In the case of old kernels the cpuid->nent value will not be modified,
so userspace can handle both cases easily:
- If KVM_GET_SUPPORTED_CPUID returned -E2BIG, check cpuid->nent
- If zero, do same -E2BIG loop as we do now.
- If not, allocate amount needed and pass it to the ioctl again.
--
Sasha.
next prev parent reply other threads:[~2011-11-24 10:38 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-17 10:18 [PATCH 1/2] KVM: Don't fail KVM_GET_SUPPORTED_CPUID if nent is just right Sasha Levin
2011-11-17 10:18 ` [PATCH 2/2] KVM: Correct documentation of KVM_GET_SUPPORTED_CPUID Sasha Levin
2011-12-04 17:37 ` Sasha Levin
2011-11-24 10:09 ` [PATCH 1/2] KVM: Don't fail KVM_GET_SUPPORTED_CPUID if nent is just right Marcelo Tosatti
2011-11-24 10:31 ` Sasha Levin
2011-11-24 10:33 ` Avi Kivity
2011-11-24 10:37 ` Sasha Levin [this message]
2011-11-24 10:45 ` Avi Kivity
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