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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH v7] xen/pt: reserve PCI slot 2 for Intel igd-passthru
On 1/9/2023 7:05 PM, Chuck Zmudzinski wrote: > On 1/9/23 6:33 PM, Michael S. Tsirkin wrote: > > On Mon, Jan 09, 2023 at 04:55:42PM -0500, Chuck Zmudzinski wrote: > >> Intel specifies that the Intel IGD must occupy slot 2 on the PCI bus, > >> as noted in docs/igd-assign.txt in the Qemu source code. > >> > >> Currently, when the xl toolstack is used to configure a Xen HVM guest with > >> Intel IGD passthrough to the guest with the Qemu upstream device model, > >> a Qemu emulated PCI device will occupy slot 2 and the Intel IGD will occupy > >> a different slot. This problem often prevents the guest from booting. > >> > >> The only available workaround is not good: Configure Xen HVM guests to use > >> the old and no longer maintained Qemu traditional device model available > >> from xenbits.xen.org which does reserve slot 2 for the Intel IGD. > >> > >> To implement this feature in the Qemu upstream device model for Xen HVM > >> guests, introduce the following new functions, types, and macros: > >> > >> * XEN_PT_DEVICE_CLASS declaration, based on the existing TYPE_XEN_PT_DEVICE > >> * XEN_PT_DEVICE_GET_CLASS macro helper function for XEN_PT_DEVICE_CLASS > >> * typedef XenPTQdevRealize function pointer > >> * XEN_PCI_IGD_SLOT_MASK, the value of slot_reserved_mask to reserve slot 2 > >> * xen_igd_reserve_slot and xen_igd_clear_slot functions > >> > >> The new xen_igd_reserve_slot function uses the existing slot_reserved_mask > >> member of PCIBus to reserve PCI slot 2 for Xen HVM guests configured using > >> the xl toolstack with the gfx_passthru option enabled, which sets the > >> igd-passthru=on option to Qemu for the Xen HVM machine type. > >> > >> The new xen_igd_reserve_slot function also needs to be implemented in > >> hw/xen/xen_pt_stub.c to prevent FTBFS during the link stage for the case > >> when Qemu is configured with --enable-xen and > >> --disable-xen-pci-passthrough, > >> in which case it does nothing. > >> > >> The new xen_igd_clear_slot function overrides qdev->realize of the parent > >> PCI device class to enable the Intel IGD to occupy slot 2 on the PCI bus > >> since slot 2 was reserved by xen_igd_reserve_slot when the PCI bus was > >> created in hw/i386/pc_piix.c for the case when igd-passthru=on. > >> > >> Move the call to xen_host_pci_device_get, and the associated error > >> handling, from xen_pt_realize to the new xen_igd_clear_slot function to > >> initialize the device class and vendor values which enables the checks for > >> the Intel IGD to succeed. The verification that the host device is an > >> Intel IGD to be passed through is done by checking the domain, bus, slot, > >> and function values as well as by checking that gfx_passthru is enabled, > >> the device class is VGA, and the device vendor in Intel. > >> > >> Signed-off-by: Chuck Zmudzinski <brchuckz@xxxxxxx> > >> --- > >> Notes that might be helpful to reviewers of patched code in hw/xen: > >> > >> The new functions and types are based on recommendations from Qemu docs: > >> https://qemu.readthedocs.io/en/latest/devel/qom.html > >> > >> Notes that might be helpful to reviewers of patched code in hw/i386: > >> > >> The small patch to hw/i386/pc_piix.c is protected by CONFIG_XEN so it does > >> not affect builds that do not have CONFIG_XEN defined. > > > > I'm not sure how you can claim that. > > I mean the small patch to pc_piix.c in this patch sits > between an "#ifdef CONFIG_XEN" and the corresponding > "#endif" so the preprocessor will exclude it when CONFIG_XEN > is not defined. In other words, my patch is part of the > xen-specific code in pc_piix.c. Or am I missing something? > > > > > > ... > > > >> diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c > >> index b48047f50c..34a9736b5e 100644 > >> --- a/hw/i386/pc_piix.c > >> +++ b/hw/i386/pc_piix.c > >> @@ -32,6 +32,7 @@ > >> #include "hw/i386/pc.h" > >> #include "hw/i386/apic.h" > >> #include "hw/pci-host/i440fx.h" > >> +#include "hw/rtc/mc146818rtc.h" > >> #include "hw/southbridge/piix.h" > >> #include "hw/display/ramfb.h" > >> #include "hw/firmware/smbios.h" > >> @@ -40,16 +41,16 @@ > >> #include "hw/usb.h" > >> #include "net/net.h" > >> #include "hw/ide/pci.h" > >> -#include "hw/ide/piix.h" > >> #include "hw/irq.h" > >> #include "sysemu/kvm.h" > >> #include "hw/kvm/clock.h" > >> #include "hw/sysbus.h" > >> +#include "hw/i2c/i2c.h" > >> #include "hw/i2c/smbus_eeprom.h" > >> #include "hw/xen/xen-x86.h" > >> +#include "hw/xen/xen.h" > >> #include "exec/memory.h" > >> #include "hw/acpi/acpi.h" > >> -#include "hw/acpi/piix4.h" > >> #include "qapi/error.h" > >> #include "qemu/error-report.h" > >> #include "sysemu/xen.h" > >> @@ -66,6 +67,7 @@ > >> #include "kvm/kvm-cpu.h" > >> > >> #define MAX_IDE_BUS 2 > >> +#define XEN_IOAPIC_NUM_PIRQS 128ULL > >> > >> #ifdef CONFIG_IDE_ISA > >> static const int ide_iobase[MAX_IDE_BUS] = { 0x1f0, 0x170 }; > >> @@ -73,6 +75,32 @@ static const int ide_iobase2[MAX_IDE_BUS] = { 0x3f6, > >> 0x376 }; > >> static const int ide_irq[MAX_IDE_BUS] = { 14, 15 }; > >> #endif > >> > >> +/* > >> + * Return the global irq number corresponding to a given device irq > >> + * pin. We could also use the bus number to have a more precise mapping. > >> + */ > >> +static int pci_slot_get_pirq(PCIDevice *pci_dev, int pci_intx) > >> +{ > >> + int slot_addend; > >> + slot_addend = PCI_SLOT(pci_dev->devfn) - 1; > >> + return (pci_intx + slot_addend) & 3; > >> +} > >> + > >> +static void piix_intx_routing_notifier_xen(PCIDevice *dev) > >> +{ > >> + int i; > >> + > >> + /* Scan for updates to PCI link routes (0x60-0x63). */ > >> + for (i = 0; i < PIIX_NUM_PIRQS; i++) { > >> + uint8_t v = dev->config_read(dev, PIIX_PIRQCA + i, 1); > >> + if (v & 0x80) { > >> + v = 0; > >> + } > >> + v &= 0xf; > >> + xen_set_pci_link_route(i, v); > >> + } > >> +} > >> + > >> /* PC hardware initialisation */ > >> static void pc_init1(MachineState *machine, > >> const char *host_type, const char *pci_type) > >> @@ -84,7 +112,7 @@ static void pc_init1(MachineState *machine, > >> MemoryRegion *system_io = get_system_io(); > >> PCIBus *pci_bus; > >> ISABus *isa_bus; > >> - int piix3_devfn = -1; > >> + Object *piix4_pm; > >> qemu_irq smi_irq; > >> GSIState *gsi_state; > >> BusState *idebus[MAX_IDE_BUS]; > >> @@ -205,10 +233,9 @@ static void pc_init1(MachineState *machine, > >> gsi_state = pc_gsi_create(&x86ms->gsi, pcmc->pci_enabled); > >> > >> if (pcmc->pci_enabled) { > >> - PIIX3State *piix3; > >> + DeviceState *dev; > >> PCIDevice *pci_dev; > >> - const char *type = xen_enabled() ? TYPE_PIIX3_XEN_DEVICE > >> - : TYPE_PIIX3_DEVICE; > >> + int i; > >> > >> pci_bus = i440fx_init(pci_type, > >> i440fx_host, > >> @@ -216,21 +243,65 @@ static void pc_init1(MachineState *machine, > >> x86ms->below_4g_mem_size, > >> x86ms->above_4g_mem_size, > >> pci_memory, ram_memory); > >> + pci_bus_map_irqs(pci_bus, > >> + xen_enabled() ? xen_pci_slot_get_pirq > >> + : pci_slot_get_pirq); > >> pcms->bus = pci_bus; > >> > >> - pci_dev = pci_create_simple_multifunction(pci_bus, -1, true, > >> type); > >> - piix3 = PIIX3_PCI_DEVICE(pci_dev); > >> - piix3->pic = x86ms->gsi; > >> - piix3_devfn = piix3->dev.devfn; > >> - isa_bus = ISA_BUS(qdev_get_child_bus(DEVICE(piix3), "isa.0")); > >> + pci_dev = pci_new_multifunction(-1, true, TYPE_PIIX3_DEVICE); > >> + object_property_set_bool(OBJECT(pci_dev), "has-usb", > >> + machine_usb(machine), &error_abort); > >> + object_property_set_bool(OBJECT(pci_dev), "has-acpi", > >> + x86_machine_is_acpi_enabled(x86ms), > >> + &error_abort); > >> + qdev_prop_set_uint32(DEVICE(pci_dev), "smb_io_base", 0xb100); > >> + object_property_set_bool(OBJECT(pci_dev), "smm-enabled", > >> + x86_machine_is_smm_enabled(x86ms), > >> + &error_abort); > >> + pci_realize_and_unref(pci_dev, pci_bus, &error_fatal); > >> + > >> + if (xen_enabled()) { > >> + pci_device_set_intx_routing_notifier( > >> + pci_dev, piix_intx_routing_notifier_xen); > >> + > >> + /* > >> + * Xen supports additional interrupt routes from the PCI > >> devices to > >> + * the IOAPIC: the four pins of each PCI device on the bus > >> are also > >> + * connected to the IOAPIC directly. > >> + * These additional routes can be discovered through ACPI. > >> + */ > >> + pci_bus_irqs(pci_bus, xen_intx_set_irq, pci_dev, > >> + XEN_IOAPIC_NUM_PIRQS); > >> + } > >> + > >> + dev = DEVICE(object_resolve_path_component(OBJECT(pci_dev), > >> "pic")); > >> + for (i = 0; i < ISA_NUM_IRQS; i++) { > >> + qdev_connect_gpio_out(dev, i, x86ms->gsi[i]); > >> + } > >> + isa_bus = ISA_BUS(qdev_get_child_bus(DEVICE(pci_dev), "isa.0")); > >> + rtc_state = > >> ISA_DEVICE(object_resolve_path_component(OBJECT(pci_dev), > >> + "rtc")); > >> + piix4_pm = object_resolve_path_component(OBJECT(pci_dev), "pm"); > >> + dev = DEVICE(object_resolve_path_component(OBJECT(pci_dev), > >> "ide")); > >> + pci_ide_create_devs(PCI_DEVICE(dev)); > >> + idebus[0] = qdev_get_child_bus(dev, "ide.0"); > >> + idebus[1] = qdev_get_child_bus(dev, "ide.1"); > >> } else { > >> pci_bus = NULL; > >> + piix4_pm = NULL; > >> isa_bus = isa_bus_new(NULL, get_system_memory(), system_io, > >> &error_abort); > >> + isa_bus_irqs(isa_bus, x86ms->gsi); > >> + > >> + rtc_state = isa_new(TYPE_MC146818_RTC); > >> + qdev_prop_set_int32(DEVICE(rtc_state), "base_year", 2000); > >> + isa_realize_and_unref(rtc_state, isa_bus, &error_fatal); > >> + > >> i8257_dma_init(isa_bus, 0); > >> pcms->hpet_enabled = false; > >> + idebus[0] = NULL; > >> + idebus[1] = NULL; > >> } > >> - isa_bus_irqs(isa_bus, x86ms->gsi); > >> > >> if (x86ms->pic == ON_OFF_AUTO_ON || x86ms->pic == ON_OFF_AUTO_AUTO) { > >> pc_i8259_create(isa_bus, gsi_state->i8259_irq); > >> @@ -252,18 +323,12 @@ static void pc_init1(MachineState *machine, > >> } > >> > >> /* init basic PC hardware */ > >> - pc_basic_device_init(pcms, isa_bus, x86ms->gsi, &rtc_state, true, > >> + pc_basic_device_init(pcms, isa_bus, x86ms->gsi, rtc_state, true, > >> 0x4); > >> > >> pc_nic_init(pcmc, isa_bus, pci_bus); > >> > >> if (pcmc->pci_enabled) { > >> - PCIDevice *dev; > >> - > >> - dev = pci_create_simple(pci_bus, piix3_devfn + 1, TYPE_PIIX3_IDE); > >> - pci_ide_create_devs(dev); > >> - idebus[0] = qdev_get_child_bus(&dev->qdev, "ide.0"); > >> - idebus[1] = qdev_get_child_bus(&dev->qdev, "ide.1"); > >> pc_cmos_init(pcms, idebus[0], idebus[1], rtc_state); > >> } > >> #ifdef CONFIG_IDE_ISA > >> @@ -289,21 +354,9 @@ static void pc_init1(MachineState *machine, > >> } > >> #endif > >> > >> - if (pcmc->pci_enabled && machine_usb(machine)) { > >> - pci_create_simple(pci_bus, piix3_devfn + 2, "piix3-usb-uhci"); > >> - } > >> - > >> - if (pcmc->pci_enabled && > >> x86_machine_is_acpi_enabled(X86_MACHINE(pcms))) { > >> - PCIDevice *piix4_pm; > >> - > >> + if (piix4_pm) { > >> smi_irq = qemu_allocate_irq(pc_acpi_smi_interrupt, first_cpu, 0); > >> - piix4_pm = pci_new(piix3_devfn + 3, TYPE_PIIX4_PM); > >> - qdev_prop_set_uint32(DEVICE(piix4_pm), "smb_io_base", 0xb100); > >> - qdev_prop_set_bit(DEVICE(piix4_pm), "smm-enabled", > >> - x86_machine_is_smm_enabled(x86ms)); > >> - pci_realize_and_unref(piix4_pm, pci_bus, &error_fatal); > >> > >> - qdev_connect_gpio_out(DEVICE(piix4_pm), 0, x86ms->gsi[9]); > >> qdev_connect_gpio_out_named(DEVICE(piix4_pm), "smi-irq", 0, > >> smi_irq); > >> pcms->smbus = I2C_BUS(qdev_get_child_bus(DEVICE(piix4_pm), > >> "i2c")); > >> /* TODO: Populate SPD eeprom data. */ > >> @@ -315,7 +368,7 @@ static void pc_init1(MachineState *machine, > >> object_property_allow_set_link, > >> OBJ_PROP_LINK_STRONG); > >> object_property_set_link(OBJECT(machine), > >> PC_MACHINE_ACPI_DEVICE_PROP, > >> - OBJECT(piix4_pm), &error_abort); > >> + piix4_pm, &error_abort); > >> } > >> > >> if (machine->nvdimms_state->is_enabled) { > >> @@ -405,6 +458,9 @@ static void pc_xen_hvm_init(MachineState *machine) > >> } > >> > >> pc_xen_hvm_init_pci(machine); > >> + if (xen_igd_gfx_pt_enabled()) { > >> + xen_igd_reserve_slot(pcms->bus); > >> + } These are the three lines from my patch that are added to pc_piix.c. IIUC, this diff is showing the differences in pc_piix.c without and with CONFIG_XEN defined. If so, then the fact that the lines in my patch are added when CONFIG_XEN is defined means they are not included as part of the build when CONFIG_XEN is not defined. That is how I can claim that my small patch to pc_piix.c does not affect builds without CONFIG_XEN defined. I also think the rest of the files touched by my patch are only included by the meson build system with the --enable-xen an option to configure. So the entire patch is xen-specific and can easily be eliminated from any build with the --disable-xen configure option. Kind regards, Chuck > >> pci_create_simple(pcms->bus, -1, "xen-platform"); > >> } > >> #endif > >> @@ -441,6 +497,11 @@ static void > >> pc_i440fx_8_0_machine_options(MachineClass *m) > >> pc_i440fx_machine_options(m); > >> m->alias = "pc"; > >> m->is_default = true; > >> +#ifdef CONFIG_MICROVM_DEFAULT > >> + m->is_default = false; > >> +#else > >> + m->is_default = true; > >> +#endif > >> } > >> > >> DEFINE_I440FX_MACHINE(v8_0, "pc-i440fx-8.0", NULL, > > > > > > Lots of changes here not guarded by CONFIG_XEN. > > > > What diff is this? How is my patch related to it? >
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