[PATCH] drm/amdkfd: add ACPI SRAT parsing for topology

[Eric Huang]

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 at amd.com>
---
 drivers/gpu/drm/amd/amdkfd/kfd_crat.c | 91 +++++++++++++++++++++++++++
 1 file changed, 91 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_crat.c b/drivers/gpu/drm/amd/amdkfd/kfd_crat.c
index 38d45711675f..0972b1014d6f 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_crat.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_crat.c
@@ -1759,6 +1759,92 @@ 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
@@ -1804,6 +1890,11 @@ 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;
-- 
2.17.1