Ping... Thanks Tiejun
On 2014/9/30 10:43, Chen, Tiejun wrote:
On 2014/9/29 18:01, Michael S. Tsirkin wrote:On Sun, Sep 28, 2014 at 10:59:05AM +0800, Chen, Tiejun wrote:On 2014/9/3 9:40, Kay, Allen M wrote:-----Original Message----- From: Chen, Tiejun Sent: Monday, September 01, 2014 12:50 AM To: Michael S. Tsirkin Cc: xen-de...@lists.xensource.com; Kay, Allen M; qemu-devel@nongnu.org; Konrad Rzeszutek Wilk Subject: Re: [Qemu-devel] [Xen-devel] [PATCH 2/2] xen:i386:pc_piix: create isa bridge specific to IGD passthrough On 2014/9/1 14:05, Michael S. Tsirkin wrote:On Mon, Sep 01, 2014 at 10:50:37AM +0800, Chen, Tiejun wrote:On 2014/8/31 16:58, Michael S. Tsirkin wrote:On Fri, Aug 29, 2014 at 09:28:50AM +0800, Chen, Tiejun wrote:On 2014/8/28 8:56, Chen, Tiejun wrote:+ */ + dev = pci_create_simple(bus, PCI_DEVFN(0x1f, 0), + "xen-igd-passthrough-isa-bridge"); + if (dev) { + r = xen_host_pci_device_get(&hdev, 0, 0, + PCI_DEVFN(0x1f, 0), 0); + if (!r) { + pci_config_set_vendor_id(dev->config,hdev.vendor_id);+ pci_config_set_device_id(dev->config, + hdev.device_id);Can you, instead, implement the reverse logic, probing the card and supplying the correct device id for PCH?Here what is your so-called reverse logic as I already asked you previously? Do you mean I should list all PCHs with a combo illustrated with the vendor/device id in advance? Then look up if we can find aMichael,Ping. Thanks TiejunCould you explain this exactly? Then I can try follow-up your idea ASAP if this is necessary and possible.Michel, Could you give us some explanation for your "reverse logic" when you're free? Thanks TiejunSo future drivers will look at device ID for the card and figure out how things should work from there. Old drivers still poke at device id of the chipset for this, but maybe qemu can do what newer drivers do: look at the card and figure out what guest should do, then present the appropriate chipset id. This is based on what Jesse said: Practically speaking, we could probably assume specific GPU/PCHcombos,as I don't think they're generally mixed across generations, thoughSNBand IVB did have compatible sockets, so there is the possibility of mixing CPT and PPT PCHs, but those are register identical as far as the graphics driver is concerned, so even that should be safe.Michael, Thanks for your explanation.so the idea is to have a reverse table mapping GPU back to PCH. Present to guest the ID that will let it assume the correct GPU.I guess you mean we should create to maintain such a table: [GPU Card: device_id(s), PCH: device_id] Then each time, instead of exposing that real PCH device id directly, qemu first can get the real GPU device id to lookup this table to present a appropriate PCH's device id to the guest. And looks here that appropriate PCH's device id is not always a that real PCH's device id. Right? If I'm wrong please correct me.Exactly: we don't really care what the PCH ID is - we only need it for the guest driver to do the right thing.Agreed. I need to ask Allen to check if one given GPU card device id is always corresponding to one given PCH on both HSW and BDW currently. If yes, I can do this quickly. Otherwise I need some time to establish that sort of connection.Michael, Sorry for this delay response but please keep in mind we really are in this process. You know this involve different GPU components we have to take some time to communicate or even discuss internal. Now I have a draft codes, could you take a look at this? I hope that comment can help us to understand something, but if you have any question, we can further respond inline. --- typedef struct { uint16_t gpu_device_id; uint16_t pch_device_id; } XenIGDDeviceIDInfo; /* In real world different GPU should have different PCH. But actually * the different PCH DIDs likely map to different PCH SKUs. We do the * same thing for the GPU. For PCH, the different SKUs are going to be * all the same silicon design and implementation, just different * features turn on and off with fuses. The SW interfaces should be * consistent across all SKUs in a given family (eg LPT). But just same * features may not be supported. * * Most of these different PCH features probably don't matter to the * Gfx driver, but obviously any difference in display port connections * will so it should be fine with any PCH in case of passthrough. * * So currently use one PCH version, 0x8c4e, to cover all HSW scenarios, * 0x9cc3 for BDW.Pls write Haswell and Broadwell in full in comment.Are you saying I should list all PCH device ids both of HSW and BDW here like this format? HSWGT1D: 0xABCD ...*/ static const XenIGDDeviceIDInfo xen_igd_combo_id_infos[] = { /* HSW Classic */ {0x0402, 0x8c4e}, /* HSWGT1D, HSWD_w7 */ {0x0406, 0x8c4e}, /* HSWGT1M, HSWM_w7 */ {0x0412, 0x8c4e}, /* HSWGT2D, HSWD_w7 */ {0x0416, 0x8c4e}, /* HSWGT2M, HSWM_w7 */ {0x041E, 0x8c4e}, /* HSWGT15D, HSWD_w7 */ /* HSW ULT */ {0x0A06, 0x8c4e}, /* HSWGT1UT, HSWM_w7 */ {0x0A16, 0x8c4e}, /* HSWGT2UT, HSWM_w7 */ {0x0A26, 0x8c4e}, /* HSWGT3UT, HSWM_w7 */ {0x0A2E, 0x8c4e}, /* HSWGT3UT28W, HSWM_w7 */ {0x0A1E, 0x8c4e}, /* HSWGT2UX, HSWM_w7 */ {0x0A0E, 0x8c4e}, /* HSWGT1ULX, HSWM_w7 */ /* HSW CRW */ {0x0D26, 0x8c4e}, /* HSWGT3CW, HSWM_w7 */ {0x0D22, 0x8c4e}, /* HSWGT3CWDT, HSWD_w7 */ /* HSW Server */ {0x041A, 0x8c4e}, /* HSWSVGT2, HSWD_w7 */ /* HSW SRVR */ {0x040A, 0x8c4e}, /* HSWSVGT1, HSWD_w7 */ /* BSW */ {0x1606, 0x9cc3}, /* BDWULTGT1, BDWM_w7 */ {0x1616, 0x9cc3}, /* BDWULTGT2, BDWM_w7 */ {0x1626, 0x9cc3}, /* BDWULTGT3, BDWM_w7 */ {0x160E, 0x9cc3}, /* BDWULXGT1, BDWM_w7 */ {0x161E, 0x9cc3}, /* BDWULXGT2, BDWM_w7 */ {0x1602, 0x9cc3}, /* BDWHALOGT1, BDWM_w7 */ {0x1612, 0x9cc3}, /* BDWHALOGT2, BDWM_w7 */ {0x1622, 0x9cc3}, /* BDWHALOGT3, BDWM_w7 */ {0x162B, 0x9cc3}, /* BDWHALO28W, BDWM_w7 */ {0x162A, 0x9cc3}, /* BDWGT3WRKS, BDWM_w7 */ {0x162D, 0x9cc3}, /* BDWGT3SRVR, BDWM_w7 */ }; static void xen_igd_passthrough_pciisabridge_get_pci_device_id(Object *obj, Visitor *v, void *opaque, const char *name, Error **errp) { uint32_t value = 0; XenHostPCIDevice hdev; int r = 0, num; r = xen_host_pci_device_get(&hdev, 0, 0, 0x02, 0); if (!r) { value = hdev.device_id; num = sizeof(xen_igd_combo_id_infos)/sizeof(uint16_t); for (r = 0; r < num; r++) if (value == xen_igd_combo_id_infos[r].gpu_device_id) value = xen_igd_combo_id_infos[r].pch_device_id;that's messy, I would use different variables for ID of GPU and PCH.for (r = 0; r < num; r++) if (gpu_id == xen_igd_combo_id_infos[r].gpu_device_id) pch_id = xen_igd_combo_id_infos[r].pch_device_id;} visit_type_uint32(v, &value, name, errp);what I was suggesting is to start with the GPU device ID (you can get it e.g. from the config array).I think current codes is doing this: r = xen_host_pci_device_get(&hdev, 0, 0, 0x02, 0); if (!r) { gpu_id = hdev.device_id; Here xen_host_pci_device_get() is a wrapper of reading pci sysfs.Use that to look up the PCH ID in xen_igd_combo_id_infos. If there, override the PCH ID. If not there, this is a new device so its driver will not look at PCH at all, we can make it whatever or skip it completely.I think we should return one initialized value, 0xffff, since often this represents an invalid PCI device.This seems to almost do this, however - Why are you looking at host PCH device ID at all? - Why don't you look at the GPU device ID?We still fix this bridge at 1f.0, and current our implementation can cover our requirement and safe. I means this bridge should not be used for other use cases, so if its still be accessed we mightn't take care of them, right?} static void xen_igd_passthrough_isa_bridge_initfn(Object *obj) { object_property_add(obj, "device-id", "int", xen_igd_passthrough_pciisabridge_get_pci_device_id, NULL, NULL, NULL, NULL); }OK and what reads this property?In sequent patch I will do something like this, @@ -464,6 +464,32 @@ static void pc_xen_hvm_init(MachineState *machine) } } +static void xen_igd_passthrough_isa_bridge_create(PCIBus *bus) +{ + struct PCIDevice *dev; + Error *local_err = NULL; + uint16_t device_id = 0xffff; + + /* Currently IGD drivers always need to access PCH by 1f.0. */ + dev = pci_create_simple(bus, PCI_DEVFN(0x1f, 0), + "xen-igd-passthrough-isa-bridge"); + + /* Identify PCH card with its own real vendor/device ids. + * Here that vendor id is always PCI_VENDOR_ID_INTEL. + */ + if (dev) { + device_id = (uint16_t)object_property_get_int(OBJECT(dev), + "device-id", + &local_err); + if ((!local_err) && (device_id != 0xffff)) { + pci_config_set_device_id(dev->config, device_id); + return; + } + } + + fprintf(stderr, "xen set xen-igd-passthrough-isa-bridge failed\n"); +} + static void xen_igd_passthrough_pc_hvm_init(MachineState *machine) { PCIBus *bus; @@ -473,6 +499,7 @@ static void xen_igd_passthrough_pc_hvm_init(MachineState *machine) bus = pci_find_primary_bus(); if (bus != NULL) { pci_create_simple(bus, -1, "xen-platform"); + xen_igd_passthrough_isa_bridge_create(bus); } } #endif TiejunThanks TiejunIf I understand this correctly, the only difference is instead of reading PCH DevID/RevID from the host hardware, QEMU inserts those values into PCH virtual device by looking at the reverse mapping table it maintains. I agree the downside of doing this is the reverse mapping table may be hard to maintain. What is the advantage of doing this instead of having QEMU reading it from the host? Is it to test to make sure reverse mapping methods works before it is adopted in the new drivers?Thanks Tiejunthe problem with these tables is they are hard to keep up to dateYeah. But I think currently we can just start from some modern CPU such as HSW and BDW, then things could be easy. Allen, Any idea to this suggestion?as new hardware comes out, but as future hardware won't need these hacks, we shall be fine.Yeah. Thanks TiejunThanks Tiejunmatched PCH? If yes, what is that benefit you expect in passthrough case? Shouldn't we pass these info to VM directly inpassthrough case?Thanks TiejunAllen
