Merge branch 'for-6.11/xor_fixes' into cxl-for-next

Series to fix XOR math for DPA to SPA translation
- Refactor and fold cxl_trace_hpa() into cxl_dpa_to_hpa()
- Complete DPA->HPA->SPA translation and correct XOR translation issue
- Add new method to verify a CXL target position
- Remove old method of CXL target position verifiation

7 files changed, 76 insertions, 112 deletions

diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
index 574918a9ae3a..82b78e331d8e 100644
--- a/drivers/cxl/acpi.c
+++ b/drivers/cxl/acpi.c
@@ -22,56 +22,42 @@ static const guid_t acpi_cxl_qtg_id_guid =
 	GUID_INIT(0xF365F9A6, 0xA7DE, 0x4071,
 		  0xA6, 0x6A, 0xB4, 0x0C, 0x0B, 0x4F, 0x8E, 0x52);
 
-/*
- * Find a targets entry (n) in the host bridge interleave list.
- * CXL Specification 3.0 Table 9-22
- */
-static int cxl_xor_calc_n(u64 hpa, struct cxl_cxims_data *cximsd, int iw,
-			  int ig)
-{
-	int i = 0, n = 0;
-	u8 eiw;
-
-	/* IW: 2,4,6,8,12,16 begin building 'n' using xormaps */
-	if (iw != 3) {
-		for (i = 0; i < cximsd->nr_maps; i++)
-			n |= (hweight64(hpa & cximsd->xormaps[i]) & 1) << i;
-	}
-	/* IW: 3,6,12 add a modulo calculation to 'n' */
-	if (!is_power_of_2(iw)) {
-		if (ways_to_eiw(iw, &eiw))
-			return -1;
-		hpa &= GENMASK_ULL(51, eiw + ig);
-		n |= do_div(hpa, 3) << i;
-	}
-	return n;
-}
 
-static struct cxl_dport *cxl_hb_xor(struct cxl_root_decoder *cxlrd, int pos)
+static u64 cxl_xor_hpa_to_spa(struct cxl_root_decoder *cxlrd, u64 hpa)
 {
 	struct cxl_cxims_data *cximsd = cxlrd->platform_data;
-	struct cxl_switch_decoder *cxlsd = &cxlrd->cxlsd;
-	struct cxl_decoder *cxld = &cxlsd->cxld;
-	int ig = cxld->interleave_granularity;
-	int iw = cxld->interleave_ways;
-	int n = 0;
-	u64 hpa;
-
-	if (dev_WARN_ONCE(&cxld->dev,
-			  cxld->interleave_ways != cxlsd->nr_targets,
-			  "misconfigured root decoder\n"))
-		return NULL;
+	int hbiw = cxlrd->cxlsd.nr_targets;
+	u64 val;
+	int pos;
 
-	hpa = cxlrd->res->start + pos * ig;
+	/* No xormaps for host bridge interleave ways of 1 or 3 */
+	if (hbiw == 1 || hbiw == 3)
+		return hpa;
 
-	/* Entry (n) is 0 for no interleave (iw == 1) */
-	if (iw != 1)
-		n = cxl_xor_calc_n(hpa, cximsd, iw, ig);
+	/*
+	 * For root decoders using xormaps (hbiw: 2,4,6,8,12,16) restore
+	 * the position bit to its value before the xormap was applied at
+	 * HPA->DPA translation.
+	 *
+	 * pos is the lowest set bit in an XORMAP
+	 * val is the XORALLBITS(HPA & XORMAP)
+	 *
+	 * XORALLBITS: The CXL spec (3.1 Table 9-22) defines XORALLBITS
+	 * as an operation that outputs a single bit by XORing all the
+	 * bits in the input (hpa & xormap). Implement XORALLBITS using
+	 * hweight64(). If the hamming weight is even the XOR of those
+	 * bits results in val==0, if odd the XOR result is val==1.
+	 */
 
-	if (n < 0)
-		return NULL;
+	for (int i = 0; i < cximsd->nr_maps; i++) {
+		if (!cximsd->xormaps[i])
+			continue;
+		pos = __ffs(cximsd->xormaps[i]);
+		val = (hweight64(hpa & cximsd->xormaps[i]) & 1);
+		hpa = (hpa & ~(1ULL << pos)) | (val << pos);
+	}
 
-	return cxlrd->cxlsd.target[n];
+	return hpa;
 }
 
 struct cxl_cxims_context {
@@ -361,7 +347,6 @@ static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
 	struct cxl_port *root_port = ctx->root_port;
 	struct cxl_cxims_context cxims_ctx;
 	struct device *dev = ctx->dev;
-	cxl_calc_hb_fn cxl_calc_hb;
 	struct cxl_decoder *cxld;
 	unsigned int ways, i, ig;
 	int rc;
@@ -389,13 +374,9 @@ static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
 	if (rc)
 		return rc;
 
-	if (cfmws->interleave_arithmetic == ACPI_CEDT_CFMWS_ARITHMETIC_MODULO)
-		cxl_calc_hb = cxl_hb_modulo;
-	else
-		cxl_calc_hb = cxl_hb_xor;
-
 	struct cxl_root_decoder *cxlrd __free(put_cxlrd) =
-		cxl_root_decoder_alloc(root_port, ways, cxl_calc_hb);
+		cxl_root_decoder_alloc(root_port, ways);
+
 	if (IS_ERR(cxlrd))
 		return PTR_ERR(cxlrd);
 
@@ -434,6 +415,9 @@ static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
 
 	cxlrd->qos_class = cfmws->qtg_id;
 
+	if (cfmws->interleave_arithmetic == ACPI_CEDT_CFMWS_ARITHMETIC_XOR)
+		cxlrd->hpa_to_spa = cxl_xor_hpa_to_spa;
+
 	rc = cxl_decoder_add(cxld, target_map);
 	if (rc)
 		return rc;
diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h
index 625394486459..72a506c9dbd0 100644
--- a/drivers/cxl/core/core.h
+++ b/drivers/cxl/core/core.h
@@ -28,12 +28,12 @@ int cxl_region_init(void);
 void cxl_region_exit(void);
 int cxl_get_poison_by_endpoint(struct cxl_port *port);
 struct cxl_region *cxl_dpa_to_region(const struct cxl_memdev *cxlmd, u64 dpa);
-u64 cxl_trace_hpa(struct cxl_region *cxlr, const struct cxl_memdev *cxlmd,
-		  u64 dpa);
+u64 cxl_dpa_to_hpa(struct cxl_region *cxlr, const struct cxl_memdev *cxlmd,
+		   u64 dpa);
 
 #else
-static inline u64
-cxl_trace_hpa(struct cxl_region *cxlr, const struct cxl_memdev *cxlmd, u64 dpa)
+static inline u64 cxl_dpa_to_hpa(struct cxl_region *cxlr,
+				 const struct cxl_memdev *cxlmd, u64 dpa)
 {
 	return ULLONG_MAX;
 }
diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c
index a08f050cc1ca..e5cdeafdf76e 100644
--- a/drivers/cxl/core/mbox.c
+++ b/drivers/cxl/core/mbox.c
@@ -878,7 +878,7 @@ void cxl_event_trace_record(const struct cxl_memdev *cxlmd,
 		dpa = le64_to_cpu(evt->media_hdr.phys_addr) & CXL_DPA_MASK;
 		cxlr = cxl_dpa_to_region(cxlmd, dpa);
 		if (cxlr)
-			hpa = cxl_trace_hpa(cxlr, cxlmd, dpa);
+			hpa = cxl_dpa_to_hpa(cxlr, cxlmd, dpa);
 
 		if (event_type == CXL_CPER_EVENT_GEN_MEDIA)
 			trace_cxl_general_media(cxlmd, type, cxlr, hpa,
diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
index e31c5fcd9bf8..82b14b39289d 100644
--- a/drivers/cxl/core/port.c
+++ b/drivers/cxl/core/port.c
@@ -1733,21 +1733,6 @@ static int decoder_populate_targets(struct cxl_switch_decoder *cxlsd,
 	return 0;
 }
 
-struct cxl_dport *cxl_hb_modulo(struct cxl_root_decoder *cxlrd, int pos)
-{
-	struct cxl_switch_decoder *cxlsd = &cxlrd->cxlsd;
-	struct cxl_decoder *cxld = &cxlsd->cxld;
-	int iw;
-
-	iw = cxld->interleave_ways;
-	if (dev_WARN_ONCE(&cxld->dev, iw != cxlsd->nr_targets,
-			  "misconfigured root decoder\n"))
-		return NULL;
-
-	return cxlrd->cxlsd.target[pos % iw];
-}
-EXPORT_SYMBOL_NS_GPL(cxl_hb_modulo, CXL);
-
 static struct lock_class_key cxl_decoder_key;
 
 /**
@@ -1807,7 +1792,6 @@ static int cxl_switch_decoder_init(struct cxl_port *port,
  * cxl_root_decoder_alloc - Allocate a root level decoder
  * @port: owning CXL root of this decoder
  * @nr_targets: static number of downstream targets
- * @calc_hb: which host bridge covers the n'th position by granularity
  *
  * Return: A new cxl decoder to be registered by cxl_decoder_add(). A
  * 'CXL root' decoder is one that decodes from a top-level / static platform
@@ -1815,8 +1799,7 @@ static int cxl_switch_decoder_init(struct cxl_port *port,
  * topology.
  */
 struct cxl_root_decoder *cxl_root_decoder_alloc(struct cxl_port *port,
-						unsigned int nr_targets,
-						cxl_calc_hb_fn calc_hb)
+						unsigned int nr_targets)
 {
 	struct cxl_root_decoder *cxlrd;
 	struct cxl_switch_decoder *cxlsd;
@@ -1838,7 +1821,6 @@ struct cxl_root_decoder *cxl_root_decoder_alloc(struct cxl_port *port,
 		return ERR_PTR(rc);
 	}
 
-	cxlrd->calc_hb = calc_hb;
 	mutex_init(&cxlrd->range_lock);
 
 	cxld = &cxlsd->cxld;
diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
index 32473fddce03..24cb74b70b66 100644
--- a/drivers/cxl/core/region.c
+++ b/drivers/cxl/core/region.c
@@ -1560,10 +1560,13 @@ static int cxl_region_attach_position(struct cxl_region *cxlr,
 				      const struct cxl_dport *dport, int pos)
 {
 	struct cxl_memdev *cxlmd = cxled_to_memdev(cxled);
+	struct cxl_switch_decoder *cxlsd = &cxlrd->cxlsd;
+	struct cxl_decoder *cxld = &cxlsd->cxld;
+	int iw = cxld->interleave_ways;
 	struct cxl_port *iter;
 	int rc;
 
-	if (cxlrd->calc_hb(cxlrd, pos) != dport) {
+	if (dport != cxlrd->cxlsd.target[pos % iw]) {
 		dev_dbg(&cxlr->dev, "%s:%s invalid target position for %s\n",
 			dev_name(&cxlmd->dev), dev_name(&cxled->cxld.dev),
 			dev_name(&cxlrd->cxlsd.cxld.dev));
@@ -2759,20 +2762,13 @@ struct cxl_region *cxl_dpa_to_region(const struct cxl_memdev *cxlmd, u64 dpa)
 	return ctx.cxlr;
 }
 
-static bool cxl_is_hpa_in_range(u64 hpa, struct cxl_region *cxlr, int pos)
+static bool cxl_is_hpa_in_chunk(u64 hpa, struct cxl_region *cxlr, int pos)
 {
 	struct cxl_region_params *p = &cxlr->params;
 	int gran = p->interleave_granularity;
 	int ways = p->interleave_ways;
 	u64 offset;
 
-	/* Is the hpa within this region at all */
-	if (hpa < p->res->start || hpa > p->res->end) {
-		dev_dbg(&cxlr->dev,
-			"Addr trans fail: hpa 0x%llx not in region\n", hpa);
-		return false;
-	}
-
 	/* Is the hpa in an expected chunk for its pos(-ition) */
 	offset = hpa - p->res->start;
 	offset = do_div(offset, gran * ways);
@@ -2785,15 +2781,26 @@ static bool cxl_is_hpa_in_range(u64 hpa, struct cxl_region *cxlr, int pos)
 	return false;
 }
 
-static u64 cxl_dpa_to_hpa(u64 dpa,  struct cxl_region *cxlr,
-			  struct cxl_endpoint_decoder *cxled)
+u64 cxl_dpa_to_hpa(struct cxl_region *cxlr, const struct cxl_memdev *cxlmd,
+		   u64 dpa)
 {
+	struct cxl_root_decoder *cxlrd = to_cxl_root_decoder(cxlr->dev.parent);
 	u64 dpa_offset, hpa_offset, bits_upper, mask_upper, hpa;
 	struct cxl_region_params *p = &cxlr->params;
-	int pos = cxled->pos;
+	struct cxl_endpoint_decoder *cxled = NULL;
 	u16 eig = 0;
 	u8 eiw = 0;
+	int pos;
 
+	for (int i = 0; i < p->nr_targets; i++) {
+		cxled = p->targets[i];
+		if (cxlmd == cxled_to_memdev(cxled))
+			break;
+	}
+	if (!cxled || cxlmd != cxled_to_memdev(cxled))
+		return ULLONG_MAX;
+
+	pos = cxled->pos;
 	ways_to_eiw(p->interleave_ways, &eiw);
 	granularity_to_eig(p->interleave_granularity, &eig);
 
@@ -2827,27 +2834,21 @@ static u64 cxl_dpa_to_hpa(u64 dpa,  struct cxl_region *cxlr,
 	/* Apply the hpa_offset to the region base address */
 	hpa = hpa_offset + p->res->start;
 
-	if (!cxl_is_hpa_in_range(hpa, cxlr, cxled->pos))
-		return ULLONG_MAX;
+	/* Root decoder translation overrides typical modulo decode */
+	if (cxlrd->hpa_to_spa)
+		hpa = cxlrd->hpa_to_spa(cxlrd, hpa);
 
-	return hpa;
-}
-
-u64 cxl_trace_hpa(struct cxl_region *cxlr, const struct cxl_memdev *cxlmd,
-		  u64 dpa)
-{
-	struct cxl_region_params *p = &cxlr->params;
-	struct cxl_endpoint_decoder *cxled = NULL;
-
-	for (int i = 0; i <  p->nr_targets; i++) {
-		cxled = p->targets[i];
-		if (cxlmd == cxled_to_memdev(cxled))
-			break;
+	if (hpa < p->res->start || hpa > p->res->end) {
+		dev_dbg(&cxlr->dev,
+			"Addr trans fail: hpa 0x%llx not in region\n", hpa);
+		return ULLONG_MAX;
 	}
-	if (!cxled || cxlmd != cxled_to_memdev(cxled))
+
+	/* Simple chunk check, by pos & gran, only applies to modulo decodes */
+	if (!cxlrd->hpa_to_spa && (!cxl_is_hpa_in_chunk(hpa, cxlr, pos)))
 		return ULLONG_MAX;
 
-	return cxl_dpa_to_hpa(dpa, cxlr, cxled);
+	return hpa;
 }
 
 static struct lock_class_key cxl_pmem_region_key;
diff --git a/drivers/cxl/core/trace.h b/drivers/cxl/core/trace.h
index 6d8b71d8f6c4..9167cfba7f59 100644
--- a/drivers/cxl/core/trace.h
+++ b/drivers/cxl/core/trace.h
@@ -704,8 +704,8 @@ TRACE_EVENT(cxl_poison,
 		if (cxlr) {
 			__assign_str(region);
 			memcpy(__entry->uuid, &cxlr->params.uuid, 16);
-			__entry->hpa = cxl_trace_hpa(cxlr, cxlmd,
-						     __entry->dpa);
+			__entry->hpa = cxl_dpa_to_hpa(cxlr, cxlmd,
+						      __entry->dpa);
 		} else {
 			__assign_str(region);
 			memset(__entry->uuid, 0, 16);
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index f46252373159..270014c0ab5c 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -432,14 +432,13 @@ struct cxl_switch_decoder {
 };
 
 struct cxl_root_decoder;
-typedef struct cxl_dport *(*cxl_calc_hb_fn)(struct cxl_root_decoder *cxlrd,
-					    int pos);
+typedef u64 (*cxl_hpa_to_spa_fn)(struct cxl_root_decoder *cxlrd, u64 hpa);
 
 /**
  * struct cxl_root_decoder - Static platform CXL address decoder
  * @res: host / parent resource for region allocations
  * @region_id: region id for next region provisioning event
- * @calc_hb: which host bridge covers the n'th position by granularity
+ * @hpa_to_spa: translate CXL host-physical-address to Platform system-physical-address
  * @platform_data: platform specific configuration data
  * @range_lock: sync region autodiscovery by address range
  * @qos_class: QoS performance class cookie
@@ -448,7 +447,7 @@ typedef struct cxl_dport *(*cxl_calc_hb_fn)(struct cxl_root_decoder *cxlrd,
 struct cxl_root_decoder {
 	struct resource *res;
 	atomic_t region_id;
-	cxl_calc_hb_fn calc_hb;
+	cxl_hpa_to_spa_fn hpa_to_spa;
 	void *platform_data;
 	struct mutex range_lock;
 	int qos_class;
@@ -774,9 +773,7 @@ bool is_root_decoder(struct device *dev);
 bool is_switch_decoder(struct device *dev);
 bool is_endpoint_decoder(struct device *dev);
 struct cxl_root_decoder *cxl_root_decoder_alloc(struct cxl_port *port,
-						unsigned int nr_targets,
-						cxl_calc_hb_fn calc_hb);
-struct cxl_dport *cxl_hb_modulo(struct cxl_root_decoder *cxlrd, int pos);
+						unsigned int nr_targets);
 struct cxl_switch_decoder *cxl_switch_decoder_alloc(struct cxl_port *port,
 						    unsigned int nr_targets);
 int cxl_decoder_add(struct cxl_decoder *cxld, int *target_map);