Re: [PATCH 0/4] xen/arm: Unbreak ACPI

["Alex Bennée" <alex.bennee@linaro.org>]

André Przywara <andre.przywara@arm.com> writes:

> On 29/09/2020 22:11, Alex Bennée wrote:
>
> Hi,
>
>> Julien Grall <julien@xen.org> writes:
>> 
>>> Hi Alex,
>>>
>>> On 29/09/2020 16:29, Alex Bennée wrote:
>>>>
>>>> Julien Grall <julien@xen.org> writes:
>>>>
>>>>> From: Julien Grall <jgrall@amazon.com>
>>>>>
>>>>> Hi all,
>>>>>
>>>>> Xen on ARM has been broken for quite a while on ACPI systems. This
>>>>> series aims to fix it.
>>>>>
>>>>> Unfortunately I don't have a system with ACPI v6.0 or later (QEMU seems
>>>>> to only support 5.1).
>
> Does QEMU provide ACPI tables? Or is this actually EDK2 generating
> them?

It certainly does - whether EDK2 mangles them afterwards is another
question. For the -M virt machine we currently generate:

  /* FADT */
  static void build_fadt_rev5(GArray *table_data, BIOSLinker *linker,
                              VirtMachineState *vms, unsigned dsdt_tbl_offset)
  {
      /* ACPI v5.1 */
      AcpiFadtData fadt = {
          .rev = 5,
          .minor_ver = 1,
          .flags = 1 << ACPI_FADT_F_HW_REDUCED_ACPI,
          .xdsdt_tbl_offset = &dsdt_tbl_offset,
      };

      switch (vms->psci_conduit) {
      case QEMU_PSCI_CONDUIT_DISABLED:
          fadt.arm_boot_arch = 0;
          break;
      case QEMU_PSCI_CONDUIT_HVC:
          fadt.arm_boot_arch = ACPI_FADT_ARM_PSCI_COMPLIANT |
                               ACPI_FADT_ARM_PSCI_USE_HVC;
          break;
      case QEMU_PSCI_CONDUIT_SMC:
          fadt.arm_boot_arch = ACPI_FADT_ARM_PSCI_COMPLIANT;
          break;
      default:
          g_assert_not_reached();
      }

      build_fadt(table_data, linker, &fadt, NULL, NULL);
  }

Looking through the code it seems we stop around 5.0 - even the new
fancy x86 microvm ACPI tables are described as /* ACPI 5.0: 4.1
Hardware-Reduced ACPI */.

>
>> So I did only some light testing.
>
> So about that v6.0 or later: it seems like the requirement comes from:
> commit 1c9bd43019cd "arm/acpi: Parse FADT table and get PSCI flags":
> "Since STAO table and the GIC version are introduced by ACPI 6.0, we
> will check the version and only parse FADT table with version >= 6.0. If
> firmware provides ACPI tables with ACPI version less than 6.0, OS will
> be messed up with those information, so disable ACPI if we get an FADT
> table with version less than 6.0."
>
> STAO (and XENV) have indeed been introduced by ACPI v6.0, but those
> tables are supposed to be *generated* by Xen and handed down to Dom0,
> they will never be provided by firmware (or parsed) by the Xen
> hypervisor. Checking the Linux code it seems to actually not (yet?)
> support the STAO named list, and currently finds and uses the STAO (UART
> block bit) regardless of the FADT version number.
>
> I can't find anything GIC related in the FADT, the whole GIC information
> is described in MADT.

I think we are generating full data for both GIC2 and GIC3:

  /* MADT */
  static void
  build_madt(GArray *table_data, BIOSLinker *linker, VirtMachineState *vms)
  {
      VirtMachineClass *vmc = VIRT_MACHINE_GET_CLASS(vms);
      int madt_start = table_data->len;
      const MemMapEntry *memmap = vms->memmap;
      const int *irqmap = vms->irqmap;
      AcpiMadtGenericDistributor *gicd;
      AcpiMadtGenericMsiFrame *gic_msi;
      int i;

      acpi_data_push(table_data, sizeof(AcpiMultipleApicTable));

      gicd = acpi_data_push(table_data, sizeof *gicd);
      gicd->type = ACPI_APIC_GENERIC_DISTRIBUTOR;
      gicd->length = sizeof(*gicd);
      gicd->base_address = cpu_to_le64(memmap[VIRT_GIC_DIST].base);
      gicd->version = vms->gic_version;

      for (i = 0; i < vms->smp_cpus; i++) {
          AcpiMadtGenericCpuInterface *gicc = acpi_data_push(table_data,
                                                             sizeof(*gicc));
          ARMCPU *armcpu = ARM_CPU(qemu_get_cpu(i));

          gicc->type = ACPI_APIC_GENERIC_CPU_INTERFACE;
          gicc->length = sizeof(*gicc);
          if (vms->gic_version == 2) {
              gicc->base_address = cpu_to_le64(memmap[VIRT_GIC_CPU].base);
              gicc->gich_base_address = cpu_to_le64(memmap[VIRT_GIC_HYP].base);
              gicc->gicv_base_address = cpu_to_le64(memmap[VIRT_GIC_VCPU].base);
          }
          gicc->cpu_interface_number = cpu_to_le32(i);
          gicc->arm_mpidr = cpu_to_le64(armcpu->mp_affinity);
          gicc->uid = cpu_to_le32(i);
          gicc->flags = cpu_to_le32(ACPI_MADT_GICC_ENABLED);

          if (arm_feature(&armcpu->env, ARM_FEATURE_PMU)) {
              gicc->performance_interrupt = cpu_to_le32(PPI(VIRTUAL_PMU_IRQ));
          }
          if (vms->virt) {
              gicc->vgic_interrupt = cpu_to_le32(PPI(ARCH_GIC_MAINT_IRQ));
          }
      }

      if (vms->gic_version == 3) {
          AcpiMadtGenericTranslator *gic_its;
          int nb_redist_regions = virt_gicv3_redist_region_count(vms);
          AcpiMadtGenericRedistributor *gicr = acpi_data_push(table_data,
                                                           sizeof *gicr);

          gicr->type = ACPI_APIC_GENERIC_REDISTRIBUTOR;
          gicr->length = sizeof(*gicr);
          gicr->base_address = cpu_to_le64(memmap[VIRT_GIC_REDIST].base);
          gicr->range_length = cpu_to_le32(memmap[VIRT_GIC_REDIST].size);

          if (nb_redist_regions == 2) {
              gicr = acpi_data_push(table_data, sizeof(*gicr));
              gicr->type = ACPI_APIC_GENERIC_REDISTRIBUTOR;
              gicr->length = sizeof(*gicr);
              gicr->base_address =
                  cpu_to_le64(memmap[VIRT_HIGH_GIC_REDIST2].base);
              gicr->range_length =
                  cpu_to_le32(memmap[VIRT_HIGH_GIC_REDIST2].size);
          }

          if (its_class_name() && !vmc->no_its) {
              gic_its = acpi_data_push(table_data, sizeof *gic_its);
              gic_its->type = ACPI_APIC_GENERIC_TRANSLATOR;
              gic_its->length = sizeof(*gic_its);
              gic_its->translation_id = 0;
              gic_its->base_address = cpu_to_le64(memmap[VIRT_GIC_ITS].base);
          }
      } else {
          gic_msi = acpi_data_push(table_data, sizeof *gic_msi);
          gic_msi->type = ACPI_APIC_GENERIC_MSI_FRAME;
          gic_msi->length = sizeof(*gic_msi);
          gic_msi->gic_msi_frame_id = 0;
          gic_msi->base_address = cpu_to_le64(memmap[VIRT_GIC_V2M].base);
          gic_msi->flags = cpu_to_le32(1);
          gic_msi->spi_count = cpu_to_le16(NUM_GICV2M_SPIS);
          gic_msi->spi_base = cpu_to_le16(irqmap[VIRT_GIC_V2M] + ARM_SPI_BASE);
      }

      build_header(linker, table_data,
                   (void *)(table_data->data + madt_start), "APIC",
                   table_data->len - madt_start, 3, NULL, NULL);
  }


>
> Linux/arm64 seems to be happy with ACPI >= v5.1:
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm64/kernel/acpi.c#n148
>
> So can we relax the v6.0 requirement, to be actually >= v5.1? That is
> among the first to support ARM anyway, IIRC.
>
> I have only a smattering about ACPI, so happy to stand corrected.

I'd certainly be happy with that as reduces the number of components
that need to be uprevved to get support.

>
> Cheers,
> Andre
>
>>>>
>>>> I was hoping to get more diagnostics out to get it working under QEMU
>>>> TCG so I think must of missed a step:
>>>>
>>>>    Loading Xen 4.15-unstable ...
>>>>    Loading Linux 4.19.0-11-arm64 ...
>>>>    Loading initial ramdisk ...
>>>>    Using modules provided by bootloader in FDT
>>>>    Xen 4.15-unstable (c/s Sat Sep 26 21:55:42 2020 +0100 git:72f3d495d0) EFI loader
>>>>    ...silence...
>>>>
>>>> I have a grub installed from testing on a buster base:
>>>>
>>>>    dpkg --status grub-arm64-efi
>>>>    Version: 2.04-8
>>>>
>>>> With:
>>>>
>>>>    GRUB_CMDLINE_LINUX_DEFAULT=""
>>>>    GRUB_CMDLINE_LINUX="console=ttyAMA0"
>>>>    GRUB_CMDLINE_LINUX_XEN_REPLACE="console=hvc0 earlyprintk=xen"
>>>>    GRUB_CMDLINE_XEN="loglvl=all guest_loglvl=all com1=115200,8n1,0x3e8,5console=com1,vg"
>>>>
>>>> And I built Xen with --enable-systemd and tweaked the hypervisor .config:
>>>>
>>>>    CONFIG_EXPERT=y
>>>>    CONFIG_ACPI=y
>>>>
>>>> So any pointers to make it more verbose would be helpful.
>>>
>>> The error is hapenning before Xen setup the console. You can get early 
>>> output on QEMU if you rebuild Xen with the following .config options:
>>>
>>> CONFIG_DEBUG=y
>>> CONFIG_EARLY_UART_CHOICE_PL011=y
>>> CONFIG_EARLY_UART_PL011=y
>>> CONFIG_EARLY_PRINTK=y
>>> CONFIG_EARLY_UART_BASE_ADDRESS=0x09000000
>>> CONFIG_EARLY_UART_PL011_BAUD_RATE=0
>>> CONFIG_EARLY_PRINTK_INC="debug-pl011.inc"
>> 
>> OK I can see it fails on the ACPI and then tries to fall back to FDT and
>> then fails to find the GIC:
>> 
>>   (XEN) CMDLINE[00000000f7bbe000]:chosen placeholder root=UUID=cf00cd3a-066b-4146-bedf-f811d3343077 ro console=hvc0 earlyprintk=xen
>>   (XEN)
>>   (XEN) Command line: placeholder loglvl=all guest_loglvl=all com1=115200,8n1,0x3e8,5console=com1,vg no-real-mode edd=off
>>   (XEN) parameter "placeholder" unknown!
>>   (XEN) parameter "no-real-mode" unknown!
>>   (XEN) parameter "edd" unknown!
>>   (XEN) ACPI: RSDP 138560000, 0024 (r2 BOCHS )
>>   (XEN) ACPI: XSDT 138550000, 004C (r1 BOCHS  BXPCFACP        1       1000013)
>>   (XEN) ACPI: FACP 138510000, 010C (r5 BOCHS  BXPCFACP        1 BXPC        1)
>>   (XEN) ACPI: DSDT 138520000, 14A6 (r2 BOCHS  BXPCDSDT        1 BXPC        1)
>>   (XEN) ACPI: APIC 138500000, 018C (r3 BOCHS  BXPCAPIC        1 BXPC        1)
>>   (XEN) ACPI: GTDT 1384F0000, 0060 (r2 BOCHS  BXPCGTDT        1 BXPC        1)
>>   (XEN) ACPI: MCFG 1384E0000, 003C (r1 BOCHS  BXPCMCFG        1 BXPC        1)
>>   (XEN) ACPI: SPCR 1384D0000, 0050 (r2 BOCHS  BXPCSPCR        1 BXPC        1)
>>   (XEN) Unsupported FADT revision 5.1, should be 6.0+, will disable ACPI
>>   (XEN) acpi_boot_table_init: FADT not found (-22)
>>   (XEN) Domain heap initialised
>>   (XEN) Booting using Device Tree
>>   (XEN) Platform: Generic System
>>   (XEN)
>>   (XEN) ****************************************
>>   (XEN) Panic on CPU 0:
>>   (XEN) Unable to find compatible GIC in the device tree
>>   (XEN) ****************************************
>>   (XEN)
>>   (XEN) Reboot in five seconds...
>> 
>> Despite saying it is going to reboot it never manages to. Any idea how
>> it is trying to reset the system?
>> 


-- 
Alex Bennée