acpi: add ATSR for q35

This patch provides ATSR which was a requirement for software that
wants to enable ATS on endpoint devices behind a Root Port. This is
done simply by setting ALL_PORTS which indicates all PCI-Express Root
Ports support ATS transactions.
Signed-off-by: NJason Wang <jasowang@redhat.com>
Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>

hw/i386/acpi-build.c

@@ -2575,6 +2575,7 @@ build_dmar_q35(GArray *table_data, BIOSLinker *linker)
 
     AcpiTableDmar *dmar;
     AcpiDmarHardwareUnit *drhd;
+    AcpiDmarRootPortATS *atsr;
     uint8_t dmar_flags = 0;
     X86IOMMUState *iommu = x86_iommu_get_default();
     AcpiDmarDeviceScope *scope = NULL;
@@ -2608,6 +2609,14 @@ build_dmar_q35(GArray *table_data, BIOSLinker *linker)
     scope->path[0].device = PCI_SLOT(Q35_PSEUDO_DEVFN_IOAPIC);
     scope->path[0].function = PCI_FUNC(Q35_PSEUDO_DEVFN_IOAPIC);
 
+    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);
+    }
+
     build_header(linker, table_data, (void *)(table_data->data + dmar_start),
                  "DMAR", table_data->len - dmar_start, 1, NULL, NULL);
 }

include/hw/acpi/acpi-defs.h

@@ -627,8 +627,20 @@ struct AcpiDmarHardwareUnit {
 } 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[0];
+} 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)