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[70.112.157.87]) by mx.google.com with ESMTPSA id r41sm30123703yhc.12.2013.06.24.05.24.04 for (version=TLSv1.2 cipher=RC4-SHA bits=128/128); Mon, 24 Jun 2013 05:24:05 -0700 (PDT) From: Anthony Liguori To: Alex Williamson In-Reply-To: <1372049162.30572.172.camel@ul30vt.home> References: <1371737338-25148-1-git-send-email-aik@ozlabs.ru> <874ncshh67.fsf@codemonkey.ws> <51C39578.6020204@ozlabs.ru> <20130623140736.GB20842@redhat.com> <1372023554.3944.111.camel@pasglop> <1372049162.30572.172.camel@ul30vt.home> User-Agent: Notmuch/0.15.2+77~g661dcf8 (http://notmuchmail.org) Emacs/23.3.1 (x86_64-pc-linux-gnu) Date: Mon, 24 Jun 2013 07:24:03 -0500 Message-ID: <87y59zbst8.fsf@codemonkey.ws> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Gm-Message-State: ALoCoQkVys354iKk+XISlJ41Hcdv8gBrDT/tdw4fMV5EfpX0JmX8K9UFr97lquruTXe5NbcyjwVp X-detected-operating-system: by eggs.gnu.org: Error: Malformed IPv6 address (bad octet value). X-Received-From: 2607:f8b0:4002:c05::22c Cc: "Michael S. Tsirkin" , qemu-trivial@nongnu.org, Benjamin Herrenschmidt , qemu-devel , qemu-ppc@nongnu.org, Paolo Bonzini , Paul Mackerras , David Gibson Subject: Re: [Qemu-trivial] [Qemu-ppc] [Qemu-devel] [PATCH] RFC kvm irqfd: add directly mapped MSI IRQ support X-BeenThere: qemu-trivial@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 24 Jun 2013 12:24:10 -0000 Alex Williamson writes: > On Sun, 2013-06-23 at 16:58 -0500, Anthony Liguori wrote: >> Yeah, but none of this is Power specific... so we can do the same for x86, no? >> >> I'm still trying to wrap my head around why we need MSI knowledge at >> all in the kernel for x86. I presume it's to fast-path irqfd when >> doing vhost? > > Or device assignment. Any paths where we want to inject an MSI > interrupt without going through userspace. Thanks, With VFIO, we use irqfd, if we program the irqfd as the underlying IRQ that MSI would route to, isn't that sufficient? That's more or less what Ben is proposing for Power... Regards, Anthony Liguori > > Alex From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43185) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Ur5oW-0003Bh-Lm for qemu-devel@nongnu.org; Mon, 24 Jun 2013 08:24:11 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Ur5oU-0008Li-UN for qemu-devel@nongnu.org; Mon, 24 Jun 2013 08:24:08 -0400 Received: from mail-yh0-x232.google.com ([2607:f8b0:4002:c01::232]:49060) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Ur5oU-0008LV-P1 for qemu-devel@nongnu.org; Mon, 24 Jun 2013 08:24:06 -0400 Received: by mail-yh0-f50.google.com with SMTP id i72so4823726yha.23 for ; Mon, 24 Jun 2013 05:24:06 -0700 (PDT) From: Anthony Liguori In-Reply-To: <1372049162.30572.172.camel@ul30vt.home> References: <1371737338-25148-1-git-send-email-aik@ozlabs.ru> <874ncshh67.fsf@codemonkey.ws> <51C39578.6020204@ozlabs.ru> <20130623140736.GB20842@redhat.com> <1372023554.3944.111.camel@pasglop> <1372049162.30572.172.camel@ul30vt.home> Date: Mon, 24 Jun 2013 07:24:03 -0500 Message-ID: <87y59zbst8.fsf@codemonkey.ws> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Subject: Re: [Qemu-devel] [Qemu-ppc] [PATCH] RFC kvm irqfd: add directly mapped MSI IRQ support List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Alex Williamson Cc: "Michael S. Tsirkin" , qemu-trivial@nongnu.org, qemu-devel , qemu-ppc@nongnu.org, Paolo Bonzini , Paul Mackerras , David Gibson Alex Williamson writes: > On Sun, 2013-06-23 at 16:58 -0500, Anthony Liguori wrote: >> Yeah, but none of this is Power specific... so we can do the same for x86, no? >> >> I'm still trying to wrap my head around why we need MSI knowledge at >> all in the kernel for x86. I presume it's to fast-path irqfd when >> doing vhost? > > Or device assignment. Any paths where we want to inject an MSI > interrupt without going through userspace. Thanks, With VFIO, we use irqfd, if we program the irqfd as the underlying IRQ that MSI would route to, isn't that sufficient? That's more or less what Ben is proposing for Power... Regards, Anthony Liguori > > Alex