From mboxrd@z Thu Jan 1 00:00:00 1970 From: Keir Fraser Subject: Re: irq_guest_eoi_timer interaction with MSI Date: Tue, 25 Nov 2008 08:30:40 +0000 Message-ID: References: <492BC215.76E4.0078.0@novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <492BC215.76E4.0078.0@novell.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Jan Beulich Cc: xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org On 25/11/08 08:15, "Jan Beulich" wrote: >> The fixmap stuff is a bit ugly and I would just have done a >> map_domain_page_global() for 32-bit Xen (good enough as far as I'm >> concerned). I'm not dead set against your approach if you like it very much, >> though. > > But just as map_domain_page(), map_domain_page_global() can't be used > out of IRQ context... I would have kept the page mapped from when it was registered until domain death. Same as we do for guest-registered vcpu_info. >> Setting the need-a-hypercall bit looks racey. Don't you need to set the bit, >> then check the guest didn't unmask meanwhile? > > We could, but I don't think it's strictly needed: The bit geting temporarily > set (as opposed to the case where it's being set for the lifetime of the IRQ) > is a performance optimization only anyway, i.e. to prevent the IRQ from > remaining masked for longer than it really needs to be. But yes, I'll see > whether the unmasking case can be taken care of without making the code > much more complicated. Yeah, okay. -- Keir