Re: [PATCH v3 18/35] acpi: build_dmar_q35: use acpi_table_begin()/acpi_table_end() instead of build_header()

[Eric Auger]

On 9/7/21 4:47 PM, Igor Mammedov wrote:
> it replaces error-prone pointer arithmetic for build_header() API,
> with 2 calls to start and finish table creation,
> which hides offsets magic from API user.
> 
> While at it switch to build_append_int_noprefix() to build
> table entries tables.
> 
> Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> ---
> v3:
>   - rebase on top 26863366b29 (hw/i386/acpi-build: Add DMAR support to bypass 
> iommu)
>   - s/acpi_init_table|acpi_table_composed/acpi_table_begin|acpi_table_end/
> 
> CC: wangxingang5@huawei.com
> CC: marcel.apfelbaum@gmail.com
> ---
>  include/hw/acpi/acpi-defs.h | 68 --------------------------
>  hw/i386/acpi-build.c        | 97 ++++++++++++++++++++-----------------
>  2 files changed, 53 insertions(+), 112 deletions(-)
> 
> diff --git a/include/hw/acpi/acpi-defs.h b/include/hw/acpi/acpi-defs.h
> index d293304f9c..c4f0a202e8 100644
> --- a/include/hw/acpi/acpi-defs.h
> +++ b/include/hw/acpi/acpi-defs.h
> @@ -358,74 +358,6 @@ struct AcpiGenericTimerTable {
>  } QEMU_PACKED;
>  typedef struct AcpiGenericTimerTable AcpiGenericTimerTable;
>  
> -/* DMAR - DMA Remapping table r2.2 */
> -struct AcpiTableDmar {
> -    ACPI_TABLE_HEADER_DEF
> -    uint8_t host_address_width; /* Maximum DMA physical addressability */
> -    uint8_t flags;
> -    uint8_t reserved[10];
> -} QEMU_PACKED;
> -typedef struct AcpiTableDmar AcpiTableDmar;
> -
> -/* Masks for Flags field above */
> -#define ACPI_DMAR_INTR_REMAP        1
> -#define ACPI_DMAR_X2APIC_OPT_OUT    (1 << 1)
> -
> -/* Values for sub-structure type for DMAR */
> -enum {
> -    ACPI_DMAR_TYPE_HARDWARE_UNIT = 0,       /* DRHD */
> -    ACPI_DMAR_TYPE_RESERVED_MEMORY = 1,     /* RMRR */
> -    ACPI_DMAR_TYPE_ATSR = 2,                /* ATSR */
> -    ACPI_DMAR_TYPE_HARDWARE_AFFINITY = 3,   /* RHSR */
> -    ACPI_DMAR_TYPE_ANDD = 4,                /* ANDD */
> -    ACPI_DMAR_TYPE_RESERVED = 5             /* Reserved for furture use */
> -};
> -
> -/*
> - * Sub-structures for DMAR
> - */
> -
> -/* Device scope structure for DRHD. */
> -struct AcpiDmarDeviceScope {
> -    uint8_t entry_type;
> -    uint8_t length;
> -    uint16_t reserved;
> -    uint8_t enumeration_id;
> -    uint8_t bus;
> -    struct {
> -        uint8_t device;
> -        uint8_t function;
> -    } path[];
> -} QEMU_PACKED;
> -typedef struct AcpiDmarDeviceScope AcpiDmarDeviceScope;
> -
> -/* Type 0: Hardware Unit Definition */
> -struct AcpiDmarHardwareUnit {
> -    uint16_t type;
> -    uint16_t length;
> -    uint8_t flags;
> -    uint8_t reserved;
> -    uint16_t pci_segment;   /* The PCI Segment associated with this unit */
> -    uint64_t address;   /* Base address of remapping hardware register-set */
> -    AcpiDmarDeviceScope scope[];
> -} QEMU_PACKED;
> -typedef struct AcpiDmarHardwareUnit AcpiDmarHardwareUnit;
> -
> -/* Type 2: Root Port ATS Capability Reporting Structure */
> -struct AcpiDmarRootPortATS {
> -    uint16_t type;
> -    uint16_t length;
> -    uint8_t flags;
> -    uint8_t reserved;
> -    uint16_t pci_segment;
> -    AcpiDmarDeviceScope scope[];
> -} QEMU_PACKED;
> -typedef struct AcpiDmarRootPortATS AcpiDmarRootPortATS;
> -
> -/* Masks for Flags field above */
> -#define ACPI_DMAR_INCLUDE_PCI_ALL   1
> -#define ACPI_DMAR_ATSR_ALL_PORTS    1
> -
>  /*
>   * Input Output Remapping Table (IORT)
>   * Conforms to "IO Remapping Table System Software on ARM Platforms",
> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> index 51e0ba07b6..2875c4f393 100644
> --- a/hw/i386/acpi-build.c
> +++ b/hw/i386/acpi-build.c
> @@ -2064,8 +2064,9 @@ build_srat(GArray *table_data, BIOSLinker *linker, 
> MachineState *machine)
>  static void
>  insert_scope(PCIBus *bus, PCIDevice *dev, void *opaque)
>  {
> +    const size_t device_scope_size = 6 /* device scope structure */ +
> +                                     2 /* 1 path entry */;
>      GArray *scope_blob = opaque;
> -    AcpiDmarDeviceScope *scope = NULL;
>  
>      if (object_dynamic_cast(OBJECT(dev), TYPE_PCI_BRIDGE)) {
>          /* Dmar Scope Type: 0x02 for PCI Bridge */
> @@ -2076,8 +2077,7 @@ insert_scope(PCIBus *bus, PCIDevice *dev, void *opaque)
>      }
>  
>      /* length */
> -    build_append_int_noprefix(scope_blob,
> -                              sizeof(*scope) + sizeof(scope->path[0]), 1);
> +    build_append_int_noprefix(scope_blob, device_scope_size, 1);
>      /* reserved */
>      build_append_int_noprefix(scope_blob, 0, 2);
>      /* enumeration_id */
> @@ -2109,26 +2109,31 @@ dmar_host_bridges(Object *obj, void *opaque)
>  }
>  
>  /*
> - * VT-d spec 8.1 DMA Remapping Reporting Structure
> - * (version Oct. 2014 or later)
> + * Intel ® Virtualization Technology for Directed I/O
> + * Architecture Specification. Revision 3.3
> + * 8.1 DMA Remapping Reporting Structure
>   */
>  static void
>  build_dmar_q35(GArray *table_data, BIOSLinker *linker, const char *oem_id,
>                 const char *oem_table_id)
>  {
> -    int dmar_start = table_data->len;
> -
> -    AcpiTableDmar *dmar;
> -    AcpiDmarHardwareUnit *drhd;
> -    AcpiDmarRootPortATS *atsr;
>      uint8_t dmar_flags = 0;
> +    uint8_t rsvd10[10] = {};
> +    /* Root complex IOAPIC uses one path only */
> +    const size_t ioapic_scope_size = 6 /* device scope structure */ +
> +                                     2 /* 1 path entry */;
>      X86IOMMUState *iommu = x86_iommu_get_default();
> -    AcpiDmarDeviceScope *scope = NULL;
> -    /* Root complex IOAPIC use one path[0] only */
> -    size_t ioapic_scope_size = sizeof(*scope) + sizeof(scope->path[0]);
>      IntelIOMMUState *intel_iommu = INTEL_IOMMU_DEVICE(iommu);
>      GArray *scope_blob = g_array_new(false, true, 1);
>  
> +    AcpiTable table = { .sig = "DMAR", .rev = 1, .oem_id = oem_id,
> +                        .oem_table_id = oem_table_id };
> +
> +    assert(iommu);
> +    if (x86_iommu_ir_supported(iommu)) {
> +        dmar_flags |= 0x1;      /* Flags: 0x1: INT_REMAP */
> +    }
> +
>      /*
>       * A PCI bus walk, for each PCI host bridge.
>       * Insert scope for each PCI bridge and endpoint device which
> @@ -2137,48 +2142,52 @@ build_dmar_q35(GArray *table_data, BIOSLinker 
> *linker, const char *oem_id,
>      object_child_foreach_recursive(object_get_root(),
>                                     dmar_host_bridges, scope_blob);
>  
> -    assert(iommu);
> -    if (x86_iommu_ir_supported(iommu)) {
> -        dmar_flags |= 0x1;      /* Flags: 0x1: INT_REMAP */
> -    }
why this move?
> -
> -    dmar = acpi_data_push(table_data, sizeof(*dmar));
> -    dmar->host_address_width = intel_iommu->aw_bits - 1;
> -    dmar->flags = dmar_flags;
> -
> -    /* DMAR Remapping Hardware Unit Definition structure */
> -    drhd = acpi_data_push(table_data, sizeof(*drhd) + ioapic_scope_size);
> -    drhd->type = cpu_to_le16(ACPI_DMAR_TYPE_HARDWARE_UNIT);
> -    drhd->length =
> -        cpu_to_le16(sizeof(*drhd) + ioapic_scope_size + scope_blob->len);
> -    drhd->flags = 0;            /* Don't include all pci device */
> -    drhd->pci_segment = cpu_to_le16(0);
> -    drhd->address = cpu_to_le64(Q35_HOST_BRIDGE_IOMMU_ADDR);
> +    acpi_table_begin(&table, table_data);
> +    /* Host Address Width */
> +    build_append_int_noprefix(table_data, intel_iommu->aw_bits - 1, 1);
> +    build_append_int_noprefix(table_data, dmar_flags, 1); /* Flags */
> +    g_array_append_vals(table_data, rsvd10, sizeof(rsvd10)); /* Reserved */
> +
> +    /* 8.3 DMAR Remapping Hardware Unit Definition structure */
> +    build_append_int_noprefix(table_data, 0, 2); /* Type */
> +    /* Length */
> +    build_append_int_noprefix(table_data,
> +                              16 + ioapic_scope_size + scope_blob->len, 2);
> +    /* Flags */
> +    build_append_int_noprefix(table_data, 0 /* Don't include all pci device 
> */ ,
> +                              1);
> +    build_append_int_noprefix(table_data, 0 , 1); /* Reserved */
> +    build_append_int_noprefix(table_data, 0 , 2); /* Segment Number */
> +    /* Register Base Address */
> +    build_append_int_noprefix(table_data, Q35_HOST_BRIDGE_IOMMU_ADDR , 8);
>  
>      /* Scope definition for the root-complex IOAPIC. See VT-d spec
>       * 8.3.1 (version Oct. 2014 or later). */
> -    scope = &drhd->scope[0];
> -    scope->entry_type = 0x03;   /* Type: 0x03 for IOAPIC */
> -    scope->length = ioapic_scope_size;
> -    scope->enumeration_id = ACPI_BUILD_IOAPIC_ID;
> -    scope->bus = Q35_PSEUDO_BUS_PLATFORM;
> -    scope->path[0].device = PCI_SLOT(Q35_PSEUDO_DEVFN_IOAPIC);
> -    scope->path[0].function = PCI_FUNC(Q35_PSEUDO_DEVFN_IOAPIC);
> +    build_append_int_noprefix(table_data, 0x03 /* IOAPIC */, 1); /* Type */
> +    build_append_int_noprefix(table_data, ioapic_scope_size, 1); /* Length */
> +    build_append_int_noprefix(table_data, 0, 2); /* Reserved */
> +    /* Enumeration ID */
> +    build_append_int_noprefix(table_data, ACPI_BUILD_IOAPIC_ID, 1);
> +    /* Start Bus Number */
> +    build_append_int_noprefix(table_data, Q35_PSEUDO_BUS_PLATFORM, 1);
> +    /* Path, {Device, Function} pair */
> +    build_append_int_noprefix(table_data, PCI_SLOT(Q35_PSEUDO_DEVFN_IOAPIC), 
> 1);
> +    build_append_int_noprefix(table_data, PCI_FUNC(Q35_PSEUDO_DEVFN_IOAPIC), 
> 1);
>  
>      /* Add scope found above */
>      g_array_append_vals(table_data, scope_blob->data, scope_blob->len);
>      g_array_free(scope_blob, true);
>  
>      if (iommu->dt_supported) {
> -        atsr = acpi_data_push(table_data, sizeof(*atsr));
> -        atsr->type = cpu_to_le16(ACPI_DMAR_TYPE_ATSR);
> -        atsr->length = cpu_to_le16(sizeof(*atsr));
> -        atsr->flags = ACPI_DMAR_ATSR_ALL_PORTS;
> -        atsr->pci_segment = cpu_to_le16(0);
> +        /* 8.5 Root Port ATS Capability Reporting Structure */
> +        build_append_int_noprefix(table_data, 2, 2); /* Type */
> +        build_append_int_noprefix(table_data, 8, 2); /* Length */
8 + no device scope
> +        build_append_int_noprefix(table_data, 1 /* ALL_PORTS */, 1); /* 
> Flags */
> +        build_append_int_noprefix(table_data, 0, 1); /* Reserved */
> +        build_append_int_noprefix(table_data, 0, 2); /* Segment Number */
>      }
>  
> -    build_header(linker, table_data, (void *)(table_data->data + dmar_start),
> -                 "DMAR", table_data->len - dmar_start, 1, oem_id, 
> oem_table_id);
> +    acpi_table_end(linker, &table);
>  }
>  
>  /*
> 
Besides
Reviewed-by: Eric Auger <eric.auger@redhat.com>

Eric