From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chris Wright Subject: Re: changing definition of paravirt_ops.iret Date: Mon, 21 May 2007 09:46:36 -0700 Message-ID: <20070521164636.GC3429@sequoia.sous-sol.org> References: <4651C865.9090605@goop.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <4651C865.9090605@goop.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: Jeremy Fitzhardinge Cc: Chris Wright , Virtualization Mailing List List-Id: virtualization@lists.linuxfoundation.org * Jeremy Fitzhardinge (jeremy@goop.org) wrote: > I'm implementing a more efficient version of the Xen iret paravirt_op, > so that it can use the real iret instruction where possible. I really > need to get access to per-cpu variables, so I can set the event mask > state in the vcpu_info structure, but unfortunately at the point where > INTERRUPT_RETURN is used in entry.S, the usermode %fs has already been > restored. > > How would you feel if we changed paravirt_ops.iret to make it also > responsible for restoring %fs? This is definitely ad-hoc semantic change, but I don't see a beter way to do it (other than have iret be restore_regs_and_iret, which isn't really an improvement). thanks, -chris