From mboxrd@z Thu Jan 1 00:00:00 1970 From: Raghavendra K T Subject: Re: [PATCH V2] Documentation/kvm: Update cpuid documentation for steal time and pv eoi Date: Thu, 12 Sep 2013 12:40:27 +0530 Message-ID: <523168E3.10405@linux.vnet.ibm.com> References: <1378284526-863-1-git-send-email-raghavendra.kt@linux.vnet.ibm.com> <20130912054453.GA13116@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Gleb Natapov , Paolo Bonzini , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Rob Landley , mtosatti@redhat.com To: "Michael S. Tsirkin" Return-path: In-Reply-To: <20130912054453.GA13116@redhat.com> Sender: linux-doc-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On 09/12/2013 11:14 AM, Michael S. Tsirkin wrote: > On Wed, Sep 04, 2013 at 02:18:46PM +0530, Raghavendra K T wrote: [...] >> ------------------------------------------------------------------------------ >> +KVM_FEATURE_STEAL_TIME || 5 || Steal time available at msr >> + || || 0x4b564d03. The feature is enabled >> + || || by guest when host has schedstat >> + || || or task delay accounting support. > > Well I think we really should be documenting the host/guest interface > here. > After all it starts out > A guest running on a kvm host, can check some of its features using > cpuid. > And guests really should not try to guess whether host > has schedstat or task delay accounting support based on this bit. > So I would just say: > "steal time can be enabled by writing to msr 0x4b564d02" > just like async pf. > It makes sense. will stick to the above line. > >> +------------------------------------------------------------------------------ >> +KVM_FEATURE_PV_EOI || 6 || overrides the generic EOI >> + || || implementation with a >> + || || paravirtualized version. Available >> + || || at msr 0x4b564d04. > > Actually there's no override: guest can still use the > standard EOI even if PV EOI MSR is enabled. > > There's a detailed explanation of PV EOI in > Documentation/virtual/kvm/msr.txt > I think the following would be enough: > > "paravirtualized end of interrupt handler can be enabled by writing to msr 0x4b564d04" > Okay. Thanks Michael.