From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Jan Beulich" Subject: use of struct hvm_mirq_dpci_mapping.gmsi vs. HVM_IRQ_DPCI_*_MSI flags Date: Thu, 31 Mar 2011 15:15:08 +0100 Message-ID: <4D94A88C0200007800039637@vpn.id2.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable Return-path: Content-Disposition: inline List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: "xen-devel@lists.xensource.com" List-Id: xen-devel@lists.xenproject.org pt_irq_create_bind_vtd() initializes this substructure only when setting .flags to HVM_IRQ_DPCI_MACH_MSI|HVM_IRQ_DPCI_GUEST_MSI (the PT_IRQ_TYPE_MSI case), while the other path will not set HVM_IRQ_DPCI_GUEST_MSI but may also set HVM_IRQ_DPCI_MACH_MSI. Yet hvm_dpci_msi_eoi() and hvm_migrate_pirqs() check for HVM_IRQ_DPCI_MACH_MSI, i.e. may run into an uninitialized .gmsi.* field. What am I missing here? I'm largely asking because I think struct hvm_mirq_dpci_mapping.dom and .digl_list could actually overlay .gmsi, as much as struct hvm_irq_dpci.hvm_timer could actually rather be folded into struct hvm_mirq_dpci_mapping (and then also overlay .gmsi). The overlay distinction bit would, based on initialization, be HVM_IRQ_DPCI_GUEST_MSI, but according to use it wouldn't be clear which of the two HVM_IRQ_DPCI_*_MSI bits is actually the correct one. Having a single structure only would make it a lot easier to convert struct hvm_mirq_dpci_mapping * in struct hvm_irq_dpci to a sparse struct hvm_mirq_dpci_mapping ** (populating slots only as they get used), thus shrinking the currently two d->nr_pirqs sized array allocations in pt_irq_create_bind_vtd() to a single one with only pointer size array elements (allowing up to about 512 domain pirqs rather than currently slightly above 80 without exceeding PAGE_SIZE on allocation). Also I'm wondering why the PT_IRQ_TYPE_MSI path of pt_irq_create_bind_vtd() checks that on re-use of an IRQ the flags are indicating the same kind of interrupt, while the other path doesn't bother doing so. Thanks, Jan