From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gleb Natapov Subject: Re: [PATCH v3 5/5] mips/kvm: Fix ABI by moving manipulation of CP0 registers to KVM_{G,S}ET_MSRS Date: Tue, 21 May 2013 19:28:11 +0300 Message-ID: <20130521162811.GE14287@redhat.com> References: <1369083686-27524-1-git-send-email-ddaney.cavm@gmail.com> <1369083686-27524-6-git-send-email-ddaney.cavm@gmail.com> <20130521153752.GD14287@redhat.com> <519B9EF2.8020107@caviumnetworks.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: David Daney , linux-mips@linux-mips.org, ralf@linux-mips.org, kvm@vger.kernel.org, Sanjay Lal , linux-kernel@vger.kernel.org, David Daney To: David Daney Return-path: Content-Disposition: inline In-Reply-To: <519B9EF2.8020107@caviumnetworks.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On Tue, May 21, 2013 at 09:21:06AM -0700, David Daney wrote: > On 05/21/2013 08:37 AM, Gleb Natapov wrote: > >On Mon, May 20, 2013 at 02:01:26PM -0700, David Daney wrote: > >>From: David Daney > >> > >>Because not all 256 CP0 registers are ever implemented, we need a > >>different method of manipulating them. Use the > >>KVM_GET_MSRS/KVM_SET_MSRS mechanism as x86 does for its MSRs. > >> > >Have you looked at KVM_(GET|SET)_ONE_REG interface (not used by x86, but is > >used bu arm/ppc/s390). It looks like it is more suitable for your case. > >Actually you can use it instead of KVM_(GET|SET)_REGS for all registers. > > Yes, I suppose it could be used. One problem it has is that there > is no way to query the set of supported registers. KVM_GET_REG_LIST > Also you have to > make multiple calls to set multiple registers, which involves > vcpu_{load,put} for each register. > How often this happens on the fast path on mips? On x86 this never happens on the fast path so it uses KVM_(GET|SET)_REGS mostly for historical reasons. > We will definitely implement it for all the FP and General Purpose > registers. > > > > >>Code related to implementing KVM_GET_MSRS/KVM_SET_MSRS is consolidated > -- Gleb.