acpi: add DMAR scope definition for root IOAPIC

To enable interrupt remapping for intel IOMMU device, each IOAPIC device
in the system reported via ACPI MADT must be explicitly enumerated under
one specific remapping hardware unit. This patch adds the root-complex
IOAPIC into the default DMAR device.

Please refer to VT-d spec 8.3.1.1 for more information.

Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 17 insertions, 3 deletions

diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
index 06682f13fc..77c40d92e2 100644
--- a/hw/i386/acpi-build.c
+++ b/hw/i386/acpi-build.c
@@ -81,6 +81,9 @@
 #define ACPI_BUILD_DPRINTF(fmt, ...)
 #endif
 
+/* Default IOAPIC ID */
+#define ACPI_BUILD_IOAPIC_ID 0x0
+
 typedef struct AcpiMcfgInfo {
     uint64_t mcfg_base;
     uint32_t mcfg_size;
@@ -384,7 +387,6 @@ build_madt(GArray *table_data, BIOSLinker *linker, PCMachineState *pcms)
     io_apic = acpi_data_push(table_data, sizeof *io_apic);
     io_apic->type = ACPI_APIC_IO;
     io_apic->length = sizeof(*io_apic);
-#define ACPI_BUILD_IOAPIC_ID 0x0
     io_apic->io_apic_id = ACPI_BUILD_IOAPIC_ID;
     io_apic->address = cpu_to_le32(IO_APIC_DEFAULT_ADDRESS);
     io_apic->interrupt = cpu_to_le32(0);
@@ -2468,6 +2470,9 @@ build_dmar_q35(GArray *table_data, BIOSLinker *linker)
     AcpiDmarHardwareUnit *drhd;
     uint8_t dmar_flags = 0;
     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]);
 
     assert(iommu);
     if (iommu->intr_supported) {
@@ -2479,13 +2484,22 @@ build_dmar_q35(GArray *table_data, BIOSLinker *linker)
     dmar->flags = dmar_flags;
 
     /* DMAR Remapping Hardware Unit Definition structure */
-    drhd = acpi_data_push(table_data, sizeof(*drhd));
+    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));   /* No device scope now */
+    drhd->length = cpu_to_le16(sizeof(*drhd) + ioapic_scope_size);
     drhd->flags = ACPI_DMAR_INCLUDE_PCI_ALL;
     drhd->pci_segment = cpu_to_le16(0);
     drhd->address = cpu_to_le64(Q35_HOST_BRIDGE_IOMMU_ADDR);
 
+    /* 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] = cpu_to_le16(Q35_PSEUDO_DEVFN_IOAPIC);
+
     build_header(linker, table_data, (void *)(table_data->data + dmar_start),
                  "DMAR", table_data->len - dmar_start, 1, NULL, NULL);
 }