[PATCH v8 12/13] cxl: Check if ULLONG_MAX was returned from translation functions

[Robert Richter <rrichter@amd.com>]

The return address of translation functions is not consistently
checked for a valid address. Check if ULLONG_MAX was returned.

Signed-off-by: Robert Richter <rrichter@amd.com>
---
 drivers/cxl/core/hdm.c                 |  2 +-
 drivers/cxl/core/region.c              | 36 +++++++++++++++++++-------
 tools/testing/cxl/test/cxl_translate.c |  4 +--
 3 files changed, 29 insertions(+), 13 deletions(-)

diff --git a/drivers/cxl/core/hdm.c b/drivers/cxl/core/hdm.c
index 1c5d2022c87a..8b50cdce4b29 100644
--- a/drivers/cxl/core/hdm.c
+++ b/drivers/cxl/core/hdm.c
@@ -530,7 +530,7 @@ resource_size_t cxl_dpa_size(struct cxl_endpoint_decoder *cxled)
 
 resource_size_t cxl_dpa_resource_start(struct cxl_endpoint_decoder *cxled)
 {
-	resource_size_t base = -1;
+	resource_size_t base = ULLONG_MAX;
 
 	lockdep_assert_held(&cxl_rwsem.dpa);
 	if (cxled->dpa_res)
diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
index c7ac78f1b644..2c070c7c7bfe 100644
--- a/drivers/cxl/core/region.c
+++ b/drivers/cxl/core/region.c
@@ -3124,7 +3124,7 @@ u64 cxl_dpa_to_hpa(struct cxl_region *cxlr, const struct cxl_memdev *cxlmd,
 	struct cxl_root_decoder *cxlrd = cxlr->cxlrd;
 	struct cxl_region_params *p = &cxlr->params;
 	struct cxl_endpoint_decoder *cxled = NULL;
-	u64 dpa_offset, hpa_offset, hpa;
+	u64 base, dpa_offset, hpa_offset, hpa;
 	u16 eig = 0;
 	u8 eiw = 0;
 	int pos;
@@ -3142,8 +3142,14 @@ u64 cxl_dpa_to_hpa(struct cxl_region *cxlr, const struct cxl_memdev *cxlmd,
 	ways_to_eiw(p->interleave_ways, &eiw);
 	granularity_to_eig(p->interleave_granularity, &eig);
 
-	dpa_offset = dpa - cxl_dpa_resource_start(cxled);
+	base = cxl_dpa_resource_start(cxled);
+	if (base == ULLONG_MAX)
+		return ULLONG_MAX;
+
+	dpa_offset = dpa - base;
 	hpa_offset = cxl_calculate_hpa_offset(dpa_offset, pos, eiw, eig);
+	if (hpa_offset == ULLONG_MAX)
+		return ULLONG_MAX;
 
 	/* Apply the hpa_offset to the region base address */
 	hpa = hpa_offset + p->res->start + p->cache_size;
@@ -3152,6 +3158,9 @@ u64 cxl_dpa_to_hpa(struct cxl_region *cxlr, const struct cxl_memdev *cxlmd,
 	if (cxlrd->ops.hpa_to_spa)
 		hpa = cxlrd->ops.hpa_to_spa(cxlrd, hpa);
 
+	if (hpa == ULLONG_MAX)
+		return ULLONG_MAX;
+
 	if (!cxl_resource_contains_addr(p->res, hpa)) {
 		dev_dbg(&cxlr->dev,
 			"Addr trans fail: hpa 0x%llx not in region\n", hpa);
@@ -3176,10 +3185,11 @@ static int region_offset_to_dpa_result(struct cxl_region *cxlr, u64 offset,
 	struct cxl_region_params *p = &cxlr->params;
 	struct cxl_root_decoder *cxlrd = cxlr->cxlrd;
 	struct cxl_endpoint_decoder *cxled;
-	u64 hpa, hpa_offset, dpa_offset;
+	u64 hpa_offset = offset;
+	u64 dpa_base, dpa_offset;
 	u16 eig = 0;
 	u8 eiw = 0;
-	int pos;
+	int pos = -1;
 
 	lockdep_assert_held(&cxl_rwsem.region);
 	lockdep_assert_held(&cxl_rwsem.dpa);
@@ -3193,13 +3203,14 @@ static int region_offset_to_dpa_result(struct cxl_region *cxlr, u64 offset,
 	 * CXL HPA is assumed to equal SPA.
 	 */
 	if (cxlrd->ops.spa_to_hpa) {
-		hpa = cxlrd->ops.spa_to_hpa(cxlrd, p->res->start + offset);
-		hpa_offset = hpa - p->res->start;
-	} else {
-		hpa_offset = offset;
+		hpa_offset = cxlrd->ops.spa_to_hpa(cxlrd, p->res->start + offset);
+		if (hpa_offset != ULLONG_MAX)
+			hpa_offset -= p->res->start;
 	}
 
-	pos = cxl_calculate_position(hpa_offset, eiw, eig);
+	if (hpa_offset != ULLONG_MAX)
+		pos = cxl_calculate_position(hpa_offset, eiw, eig);
+
 	if (pos < 0 || pos >= p->nr_targets) {
 		dev_dbg(&cxlr->dev, "Invalid position %d for %d targets\n",
 			pos, p->nr_targets);
@@ -3213,8 +3224,13 @@ static int region_offset_to_dpa_result(struct cxl_region *cxlr, u64 offset,
 		cxled = p->targets[i];
 		if (cxled->pos != pos)
 			continue;
+
+		dpa_base = cxl_dpa_resource_start(cxled);
+		if (dpa_base == ULLONG_MAX)
+			continue;
+
 		result->cxlmd = cxled_to_memdev(cxled);
-		result->dpa = cxl_dpa_resource_start(cxled) + dpa_offset;
+		result->dpa = dpa_base + dpa_offset;
 
 		return 0;
 	}
diff --git a/tools/testing/cxl/test/cxl_translate.c b/tools/testing/cxl/test/cxl_translate.c
index 2200ae21795c..66f8270aacd8 100644
--- a/tools/testing/cxl/test/cxl_translate.c
+++ b/tools/testing/cxl/test/cxl_translate.c
@@ -69,7 +69,7 @@ static u64 to_hpa(u64 dpa_offset, int pos, u8 r_eiw, u16 r_eig, u8 hb_ways,
 	/* Calculate base HPA offset from DPA and position */
 	hpa_offset = cxl_calculate_hpa_offset(dpa_offset, pos, r_eiw, r_eig);
 
-	if (math == XOR_MATH) {
+	if (hpa_offset != ULLONG_MAX && math == XOR_MATH) {
 		cximsd->nr_maps = hbiw_to_nr_maps[hb_ways];
 		if (cximsd->nr_maps)
 			return cxl_do_xormap_calc(cximsd, hpa_offset, hb_ways);
@@ -262,7 +262,7 @@ static int test_random_params(void)
 		reverse_dpa = cxl_calculate_dpa_offset(hpa, eiw, eig);
 		reverse_pos = cxl_calculate_position(hpa, eiw, eig);
 
-		if (reverse_dpa != dpa || reverse_pos != pos) {
+		if (hpa == ULLONG_MAX || reverse_dpa != dpa || reverse_pos != pos) {
 			pr_err("test random iter %d FAIL hpa=%llu, dpa=%llu reverse_dpa=%llu, pos=%d reverse_pos=%d eiw=%u eig=%u\n",
 			       i, hpa, dpa, reverse_dpa, pos, reverse_pos, eiw,
 			       eig);
-- 
2.47.3