From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eduardo Habkost Subject: Re: [PATCH 08/16] x86: Emergency virtualization disable function Date: Wed, 5 Nov 2008 15:52:35 -0200 Message-ID: <20081105175235.GJ5247@blackpad> References: <1225810364-8990-1-git-send-email-ehabkost@redhat.com> <1225810364-8990-9-git-send-email-ehabkost@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: Andrew Morton , kvm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, kexec-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, "Rafael J. Wysocki" , Haren Myneni , Simon Horman , Avi Kivity , Ingo Molnar , Andrey Borzenkov , mingo-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, Vivek Goyal To: "Eric W. Biederman" Return-path: Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kexec-bounces-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org Errors-To: kexec-bounces+glkk-kexec=m.gmane.org-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org List-Id: kvm.vger.kernel.org On Wed, Nov 05, 2008 at 09:33:06AM -0800, Eric W. Biederman wrote: > Eduardo Habkost writes: > > > +int set_virt_disable_func(void (*fn)(void)) > > +{ > > + int r = 0; > > + > > + spin_lock(&virt_disable_lock); > > + if (!virt_disable_fn) > > + rcu_assign_pointer(virt_disable_fn, fn); > > + else > > + r = -EEXIST; > > + spin_unlock(&virt_disable_lock); > > + > > + return r; > > +} > > +EXPORT_SYMBOL(set_virt_disable_func); > > EXPORT_SYMBOL_GPL? > > > +EXPORT_SYMBOL(clear_virt_disable_func); > EXPORT_SYMBOL_GPL? > > We are talking a core internal api that should not even > be exported if KVM is compiled into the kernel. > > I have had to tell people NO too many times by that > wanted to shove code on the kexec on panic path that > had no business there. I do not want to give > the least little impression that this is an ok hook > for the to use. The very specific name helps in > that regard thank you for that. Having the symbol > exported GPL would help even more. Agreed. I will change that if nobody else objects. > > Overall I think the code is just barely ok. > > I don't like the fact that to run 2-3 instructions per cpu we are two > function pointers deep. It feels like we have an excess of > abstraction here on the kvm side. > > Is it possible to have the individual kvm modules call > set_virt_disable_func and clear_virt_disable_func? Instead > of going through the x86_kvm_ops? > > It really feels like we have an excess of abstraction here. We could move the set_virt_disable_func() calls to vmx.c and svm.c (on hardware_setup/hardware_unsetup). One could argue that it is sort of a coincidence that we need the code for both vmx and svm. Avi, what do you think? -- Eduardo