drm/amdkfd: add ACPI SRAT parsing for topology

In NPS4 BIOS we need to find the closest numa node when creating
topology io link between cpu and gpu, if PCI driver doesn't set
it.
Signed-off-by: Eric Huang <jinhuieric.huang@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdkfd/kfd_crat.c

@@ -1749,6 +1749,92 @@ static int kfd_fill_gpu_memory_affinity(int *avail_size,
 	return 0;
 }
 
+#ifdef CONFIG_ACPI_NUMA
+static void kfd_find_numa_node_in_srat(struct kfd_dev *kdev)
+{
+	struct acpi_table_header *table_header = NULL;
+	struct acpi_subtable_header *sub_header = NULL;
+	unsigned long table_end, subtable_len;
+	u32 pci_id = pci_domain_nr(kdev->pdev->bus) << 16 |
+			pci_dev_id(kdev->pdev);
+	u32 bdf;
+	acpi_status status;
+	struct acpi_srat_cpu_affinity *cpu;
+	struct acpi_srat_generic_affinity *gpu;
+	int pxm = 0, max_pxm = 0;
+	int numa_node = NUMA_NO_NODE;
+	bool found = false;
+
+	/* Fetch the SRAT table from ACPI */
+	status = acpi_get_table(ACPI_SIG_SRAT, 0, &table_header);
+	if (status == AE_NOT_FOUND) {
+		pr_warn("SRAT table not found\n");
+		return;
+	} else if (ACPI_FAILURE(status)) {
+		const char *err = acpi_format_exception(status);
+		pr_err("SRAT table error: %s\n", err);
+		return;
+	}
+
+	table_end = (unsigned long)table_header + table_header->length;
+
+	/* Parse all entries looking for a match. */
+	sub_header = (struct acpi_subtable_header *)
+			((unsigned long)table_header +
+			sizeof(struct acpi_table_srat));
+	subtable_len = sub_header->length;
+
+	while (((unsigned long)sub_header) + subtable_len  < table_end) {
+		/*
+		 * If length is 0, break from this loop to avoid
+		 * infinite loop.
+		 */
+		if (subtable_len == 0) {
+			pr_err("SRAT invalid zero length\n");
+			break;
+		}
+
+		switch (sub_header->type) {
+		case ACPI_SRAT_TYPE_CPU_AFFINITY:
+			cpu = (struct acpi_srat_cpu_affinity *)sub_header;
+			pxm = *((u32 *)cpu->proximity_domain_hi) << 8 |
+					cpu->proximity_domain_lo;
+			if (pxm > max_pxm)
+				max_pxm = pxm;
+			break;
+		case ACPI_SRAT_TYPE_GENERIC_AFFINITY:
+			gpu = (struct acpi_srat_generic_affinity *)sub_header;
+			bdf = *((u16 *)(&gpu->device_handle[0])) << 16 |
+					*((u16 *)(&gpu->device_handle[2]));
+			if (bdf == pci_id) {
+				found = true;
+				numa_node = pxm_to_node(gpu->proximity_domain);
+			}
+			break;
+		default:
+			break;
+		}
+
+		if (found)
+			break;
+
+		sub_header = (struct acpi_subtable_header *)
+				((unsigned long)sub_header + subtable_len);
+		subtable_len = sub_header->length;
+	}
+
+	acpi_put_table(table_header);
+
+	/* Workaround bad cpu-gpu binding case */
+	if (found && (numa_node < 0 ||
+			numa_node > pxm_to_node(max_pxm)))
+		numa_node = 0;
+
+	if (numa_node != NUMA_NO_NODE)
+		set_dev_node(&kdev->pdev->dev, numa_node);
+}
+#endif
+
 /* kfd_fill_gpu_direct_io_link - Fill in direct io link from GPU
  * to its NUMA node
  *	@avail_size: Available size in the memory
@@ -1795,6 +1881,11 @@ static int kfd_fill_gpu_direct_io_link_to_cpu(int *avail_size,
 	}
 
 	sub_type_hdr->proximity_domain_from = proximity_domain;
+
+#ifdef CONFIG_ACPI_NUMA
+	if (kdev->pdev->dev.numa_node == NUMA_NO_NODE)
+		kfd_find_numa_node_in_srat(kdev);
+#endif
 #ifdef CONFIG_NUMA
 	if (kdev->pdev->dev.numa_node == NUMA_NO_NODE)
 		sub_type_hdr->proximity_domain_to = 0;