From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53096) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XqKKA-0002rF-Mb for qemu-devel@nongnu.org; Mon, 17 Nov 2014 06:18:31 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XqKK5-0005Wq-KC for qemu-devel@nongnu.org; Mon, 17 Nov 2014 06:18:26 -0500 Received: from mga03.intel.com ([134.134.136.65]:11061) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XqKK5-0005Vf-EB for qemu-devel@nongnu.org; Mon, 17 Nov 2014 06:18:21 -0500 Message-ID: <5469D979.8050404@intel.com> Date: Mon, 17 Nov 2014 19:18:17 +0800 From: "Chen, Tiejun" MIME-Version: 1.0 References: <1415172179-7965-1-git-send-email-tiejun.chen@intel.com> <1415172179-7965-2-git-send-email-tiejun.chen@intel.com> <20141105140906.GA4912@redhat.com> <546961DC.4040300@intel.com> <20141117061010.GB19718@redhat.com> <5469B660.6040107@intel.com> <20141117092501.GA20133@redhat.com> <5469C2F4.4020304@intel.com> <20141117101342.GF20133@redhat.com> In-Reply-To: <20141117101342.GF20133@redhat.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [RFC][PATCH 2/2] xen:i386:pc_piix: create isa bridge specific to IGD passthrough List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Michael S. Tsirkin" Cc: xen-devel@lists.xensource.com, allen.m.kay@intel.com, qemu-devel@nongnu.org, aliguori@amazon.com, pbonzini@redhat.com, rth@twiddle.net On 2014/11/17 18:13, Michael S. Tsirkin wrote: > On Mon, Nov 17, 2014 at 05:42:12PM +0800, Chen, Tiejun wrote: >> On 2014/11/17 17:25, Michael S. Tsirkin wrote: >>> On Mon, Nov 17, 2014 at 04:48:32PM +0800, Chen, Tiejun wrote: >>>> On 2014/11/17 14:10, Michael S. Tsirkin wrote: >>>>> On Mon, Nov 17, 2014 at 10:47:56AM +0800, Chen, Tiejun wrote: >>>>>> On 2014/11/5 22:09, Michael S. Tsirkin wrote: >>>>>>> On Wed, Nov 05, 2014 at 03:22:59PM +0800, Tiejun Chen wrote: >>>>>>>> Currently IGD drivers always need to access PCH by 1f.0, and >>>>>>>> PCH vendor/device id is used to identify the card. >>>>>>>> >>>>>>>> Signed-off-by: Tiejun Chen >>>>>>>> --- >> >> [snip] >> >>> Cleaner: >>> if (!pci_dev) { >>> fprintf >>> return; >>> } >>> pci_config_set_device_id(pci_dev->config, pch_id); >> >> I will address all comments and thanks. >> >>> >>>> + } >>>> +} >>>> + >>>> /* init */ >>>> >>>> static int xen_pt_initfn(PCIDevice *d) >>>> @@ -682,6 +770,9 @@ static int xen_pt_initfn(PCIDevice *d) >>>> return -1; >>>> } >>>> >>>> + /* Register ISA bridge for passthrough GFX. */ >>>> + xen_igd_passthrough_isa_bridge_create(s, &s->real_device); >>>> + >>>> /* reinitialize each config register to be emulated */ >>>> if (xen_pt_config_init(s)) { >>>> XEN_PT_ERR(d, "PCI Config space initialisation failed.\n"); >>>> >>>> Note I will introduce a inline function in another patch, >>>> >>>> +static inline int is_vga_passthrough(XenHostPCIDevice *dev) >>>> +{ >>>> + return (xen_has_gfx_passthru && (dev->vendor_id == PCI_VENDOR_ID_INTEL) >>>> + && ((dev->class_code >> 0x8) == PCI_CLASS_DISPLAY_VGA)); >>>> +} >>>> >>>> Thanks >>>> Tiejun >>> >>> Why bother with all these conditions? >>> Won't it be enough to check dev->vendor_id == PCI_VENDOR_ID_INTEL? >>> >> >> If this is just used for IGD, its always fine without checking vendor_id. > > You need to match device ID to *know* it's IGD. > >> So after remove that check, I guess I need to rename that as >> is_igd_vga_passthrough() to make sense. >> >> Thanks >> Tiejun > > There is no need to check class code or xen_has_gfx_passthru flag. > Device ID + vendor ID identifies each device uniquely. > Yeah. Here I assume vendor ID is always PCI_VENDOR_ID_INTEL so looks you means I also need to check that table to do something like, is_igd_vga_passthugh(dev) { int i; int num = ARRAY_SIZE(xen_igd_combo_id_infos); for (i = 0; i < num; i++) { if (dev->device_id == xen_igd_combo_id_infos[i].gpu_device_id) return 1; return 0; } Then we can simplify the subsequent codes based on this, right? Thanks Tiejun