From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kiszka Subject: Re: [RFC][PATCH 12/45] msi: Introduce MSIRoutingCache Date: Mon, 17 Oct 2011 13:19:56 +0200 Message-ID: <4E9C0F5C.8000602@siemens.com> References: <4E9C0C42.60201@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Marcelo Tosatti , "kvm@vger.kernel.org" , Alex Williamson , "Michael S. Tsirkin" , "qemu-devel@nongnu.org" To: Avi Kivity Return-path: Received: from goliath.siemens.de ([192.35.17.28]:16285 "EHLO goliath.siemens.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755498Ab1JQLUB (ORCPT ); Mon, 17 Oct 2011 07:20:01 -0400 In-Reply-To: <4E9C0C42.60201@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 2011-10-17 13:06, Avi Kivity wrote: > On 10/17/2011 11:27 AM, Jan Kiszka wrote: >> This cache will help us implementing KVM in-kernel irqchip support >> without spreading hooks all over the place. >> >> KVM requires us to register it first and then deliver it by raising a >> pseudo IRQ line returned on registration. While this could be changed >> for QEMU-originated MSI messages by adding direct MSI injection, we will >> still need this translation for irqfd-originated messages. The >> MSIRoutingCache will allow to track those registrations and update them >> lazily before the actual delivery. This avoid having to track MSI >> vectors at device level (like qemu-kvm currently does). >> >> >> +typedef enum { >> + MSI_ROUTE_NONE = 0, >> + MSI_ROUTE_STATIC, >> +} MSIRouteType; >> + >> +struct MSIRoutingCache { >> + MSIMessage msg; >> + MSIRouteType type; >> + int kvm_gsi; >> + int kvm_irqfd; >> +}; >> + >> diff --git a/hw/pci.h b/hw/pci.h >> index 329ab32..5b5d2fd 100644 >> --- a/hw/pci.h >> +++ b/hw/pci.h >> @@ -197,6 +197,10 @@ struct PCIDevice { >> MemoryRegion rom; >> uint32_t rom_bar; >> >> + /* MSI routing chaches */ >> + MSIRoutingCache *msi_cache; >> + MSIRoutingCache *msix_cache; >> + >> /* MSI entries */ >> int msi_entries_nr; >> struct KVMMsiMessage *msi_irq_entries; > > IMO this needlessly leaks kvm information into core qemu. The cache > should be completely hidden in kvm code. > > I think msi_deliver() can hide the use of the cache completely. For > pre-registered events like kvm's irqfd, you can use something like > > qemu_irq qemu_msi_irq(MSIMessage msg) > > for non-kvm, it simply returns a qemu_irq that triggers a stl_phys(); > for kvm, it allocates an irqfd and a permanent entry in the cache and > returns a qemu_irq that triggers the irqfd. See my previously mail: you want to track the life-cycle of an MSI source to avoid generating routes for identical sources. A messages is not a source. Two identical messages can come from different sources. So we need a separate data structure for that purpose. Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux