[PATCH v2 i-g-t 2/3] lib/xe/xe_sriov_provisioning: Refactor range handling and logging

[Marcin Bernatowicz]

Introduce an append_range helper to reduce code duplication in handling
provisioned PTE ranges. Limit debug logs to the first 70 entries for
clarity and improved reasoning. Enhance error handling by propagating
realloc failures.

v2: Update range-checking logic to iterate only within valid PTE offsets
    based on MAX_WOPCM_SIZE and GUC_GGTT_TOP.

Signed-off-by: Marcin Bernatowicz <marcin.bernatowicz at linux.intel.com>
Cc: Adam Miszczak <adam.miszczak at linux.intel.com>
Cc: C V Narasimha <narasimha.c.v at intel.com>
Cc: Jakub Kolakowski <jakub1.kolakowski at intel.com>
Cc: K V P Satyanarayana <satyanarayana.k.v.p at intel.com>
Cc: Lukasz Laguna <lukasz.laguna at intel.com>
Cc: Michał Wajdeczko <michal.wajdeczko at intel.com>
Cc: Michał Winiarski <michal.winiarski at intel.com>
Cc: Piotr Piórkowski <piotr.piorkowski at intel.com>
Cc: Tomasz Lis <tomasz.lis at intel.com>
---
 lib/xe/xe_sriov_provisioning.c | 78 +++++++++++++++++++++++-----------
 1 file changed, 53 insertions(+), 25 deletions(-)

diff --git a/lib/xe/xe_sriov_provisioning.c b/lib/xe/xe_sriov_provisioning.c
index 7cde2c240..8e2ec41e1 100644
--- a/lib/xe/xe_sriov_provisioning.c
+++ b/lib/xe/xe_sriov_provisioning.c
@@ -3,7 +3,7 @@
  * Copyright(c) 2024 Intel Corporation. All rights reserved.
  */
 
-#include <stdlib.h>
+#include <errno.h>
 
 #include "igt_core.h"
 #include "intel_chipset.h"
@@ -39,6 +39,10 @@ const char *xe_sriov_shared_res_to_string(enum xe_sriov_shared_res res)
 #define PRE_1250_IP_VER_GGTT_PTE_VFID_MASK	GENMASK_ULL(4, 2)
 #define GGTT_PTE_VFID_MASK			GENMASK_ULL(11, 2)
 #define GGTT_PTE_VFID_SHIFT			2
+#define GUC_GGTT_TOP				0xFEE00000
+#define MAX_WOPCM_SIZE				SZ_8M
+#define START_PTE_OFFSET			(MAX_WOPCM_SIZE / SZ_4K * sizeof(xe_ggtt_pte_t))
+#define MAX_PTE_OFFSET				(GUC_GGTT_TOP / SZ_4K * sizeof(xe_ggtt_pte_t))
 
 static uint64_t get_vfid_mask(int fd)
 {
@@ -48,6 +52,37 @@ static uint64_t get_vfid_mask(int fd)
 		GGTT_PTE_VFID_MASK : PRE_1250_IP_VER_GGTT_PTE_VFID_MASK;
 }
 
+#define MAX_DEBUG_ENTRIES 70
+
+static int append_range(struct xe_sriov_provisioned_range **ranges,
+			unsigned int *nr_ranges, unsigned int vf_id,
+			uint32_t start, uint32_t end)
+{
+	struct xe_sriov_provisioned_range *new_ranges;
+
+	new_ranges = realloc(*ranges,
+			     (*nr_ranges + 1) * sizeof(struct xe_sriov_provisioned_range));
+	if (!new_ranges) {
+		free(*ranges);
+		*ranges = NULL;
+		*nr_ranges = 0;
+		return -ENOMEM;
+	}
+
+	*ranges = new_ranges;
+	if (*nr_ranges < MAX_DEBUG_ENTRIES)
+		igt_debug("Found VF%u GGTT range [%#x-%#x] num_ptes=%ld\n",
+			  vf_id, start, end,
+			  (end - start + sizeof(xe_ggtt_pte_t)) /
+			  sizeof(xe_ggtt_pte_t));
+	(*ranges)[*nr_ranges].vf_id = vf_id;
+	(*ranges)[*nr_ranges].start = start;
+	(*ranges)[*nr_ranges].end = end;
+	(*nr_ranges)++;
+
+	return 0;
+}
+
 /**
  * xe_sriov_find_ggtt_provisioned_pte_offsets - Find GGTT provisioned PTE offsets
  * @pf_fd: File descriptor for the Physical Function
@@ -76,28 +111,23 @@ int xe_sriov_find_ggtt_provisioned_pte_offsets(int pf_fd, int gt, struct xe_mmio
 	uint32_t current_start = 0;
 	uint32_t current_end = 0;
 	xe_ggtt_pte_t pte;
+	int ret;
 
 	*ranges = NULL;
 	*nr_ranges = 0;
 
-	for (uint32_t offset = 0; offset < SZ_8M; offset += sizeof(xe_ggtt_pte_t)) {
+	for (uint32_t offset = START_PTE_OFFSET; offset < MAX_PTE_OFFSET;
+	     offset += sizeof(xe_ggtt_pte_t)) {
 		pte = xe_mmio_ggtt_read(mmio, gt, offset);
 		vf_id = (pte & vfid_mask) >> GGTT_PTE_VFID_SHIFT;
 
 		if (vf_id != current_vf_id) {
 			if (current_vf_id != -1) {
-				/* End the current range */
-				*ranges = realloc(*ranges, (*nr_ranges + 1) *
-						  sizeof(struct xe_sriov_provisioned_range));
-				igt_assert(*ranges);
-				igt_debug("Found VF%u ggtt range [%#x-%#x] num_ptes=%ld\n",
-					  current_vf_id, current_start, current_end,
-					  (current_end - current_start + sizeof(xe_ggtt_pte_t)) /
-					  sizeof(xe_ggtt_pte_t));
-				(*ranges)[*nr_ranges].vf_id = current_vf_id;
-				(*ranges)[*nr_ranges].start = current_start;
-				(*ranges)[*nr_ranges].end = current_end;
-				(*nr_ranges)++;
+				/* End the current range and append it */
+				ret = append_range(ranges, nr_ranges, current_vf_id,
+						   current_start, current_end);
+				if (ret < 0)
+					return ret;
 			}
 			/* Start a new range */
 			current_vf_id = vf_id;
@@ -107,18 +137,16 @@ int xe_sriov_find_ggtt_provisioned_pte_offsets(int pf_fd, int gt, struct xe_mmio
 	}
 
 	if (current_vf_id != -1) {
-		*ranges = realloc(*ranges, (*nr_ranges + 1) *
-				  sizeof(struct xe_sriov_provisioned_range));
-		igt_assert(*ranges);
-		igt_debug("Found VF%u ggtt range [%#x-%#x] num_ptes=%ld\n",
-			  current_vf_id, current_start, current_end,
-			  (current_end - current_start + sizeof(xe_ggtt_pte_t)) /
-			  sizeof(xe_ggtt_pte_t));
-		(*ranges)[*nr_ranges].vf_id = current_vf_id;
-		(*ranges)[*nr_ranges].start = current_start;
-		(*ranges)[*nr_ranges].end = current_end;
-		(*nr_ranges)++;
+		/* Append the last range */
+		ret = append_range(ranges, nr_ranges, current_vf_id,
+				   current_start, current_end);
+		if (ret < 0)
+			return ret;
 	}
 
+	if (*nr_ranges > MAX_DEBUG_ENTRIES)
+		igt_debug("Ranges output trimmed to first %u entries out of %u",
+			  MAX_DEBUG_ENTRIES, *nr_ranges);
+
 	return 0;
 }
-- 
2.31.1