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charset="utf-8" CXL r3.2 8.2.4.20.12 and 14.13.10 permit committing on HDM decoder with size 0. BIOS commits and locks such decoders to burn slots for a Type 3 device in a TSP-established TCB. init_hdm_decoder() rejected them with -ENXIO and aborted port enumeration, so "cxl list" showed nothing. Enumerate the decoder with its HW LOCK state instead. Skip the DPA reservation it does not need, but advance port->hdm_end so a following committed decoder still passes the in-order check in __cxl_dpa_reserve(). commit_end can now point at a decoder with no DPA resource, so poison_by_decoder() must still scan the unmapped DPA tail. Signed-off-by: Vishal Aslot Signed-off-by: Richard Cheng --- Changelog: v2->v3: - Advance port->hdm_end for the committed zero-size decoder so a following committed decoder still passes the in-order check in __cxl_dpa_reserve() . - commit_end may now reference a zero-size decoder with no DPA resource, so poison_by_decoder() falls through to run cxl_get_poison_unmapped() and scan the unmapped DPA tail. v1->v2: - Add zero-size committed decoders to the topology instead of skipping them. Drop v1's -ENOSPC sentinel and the matching "continue" in devm_cxl_enumerate_decoders(); fall through so add_hdm_decoder() registers the decoder. - Set port->commit_end unconditionally for any committed decoder, not only non-zero-size ones, so subsequent decoders satisfy the out-of-order check. - Add an explicit early-return before devm_cxl_dpa_reserve() in the endpoint-decoder path. __cxl_dpa_reserve() rejects zero-size decoders. - Spell out TSP and TCB and cite spec sections in commit message. - Reorder series, implementation first. --- drivers/cxl/core/hdm.c | 25 +++++++++++++++++------ drivers/cxl/core/region.c | 42 +++++++++++++++++++-------------------- 2 files changed, 40 insertions(+), 27 deletions(-) diff --git a/drivers/cxl/core/hdm.c b/drivers/cxl/core/hdm.c index 0c80b76a5f9b..b5fe2b053bc2 100644 --- a/drivers/cxl/core/hdm.c +++ b/drivers/cxl/core/hdm.c @@ -1031,13 +1031,17 @@ static int init_hdm_decoder(struct cxl_port *port, = struct cxl_decoder *cxld, return -ENXIO; } =20 - if (size =3D=3D 0) { - dev_warn(&port->dev, - "decoder%d.%d: Committed with zero size\n", - port->id, cxld->id); - return -ENXIO; - } port->commit_end =3D cxld->id; + + /* + * CXL r3.2 8.2.4.20.12 permits committing an HDM decoder with + * size 0. Enumerate it into the topology with its HW-reported + * LOCK state instead of aborting the port. + */ + if (size =3D=3D 0) + dev_dbg(&port->dev, + "decoder%d.%d: Committed with zero size\n", + port->id, cxld->id); } else { if (cxled) { struct cxl_memdev *cxlmd =3D cxled_to_memdev(cxled); @@ -1096,6 +1100,15 @@ static int init_hdm_decoder(struct cxl_port *port, s= truct cxl_decoder *cxld, if (!committed) return 0; =20 + /* + * A committed zero-size decoder reserves no DPA, but still advance + * the port's DPA watermark. + */ + if (size =3D=3D 0) { + port->hdm_end =3D cxld->id; + return 0; + } + dpa_size =3D div_u64_rem(size, cxld->interleave_ways, &remainder); if (remainder) { dev_err(&port->dev, diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c index e50dc716d4e8..a353d8e7489d 100644 --- a/drivers/cxl/core/region.c +++ b/drivers/cxl/core/region.c @@ -2907,38 +2907,38 @@ static int poison_by_decoder(struct device *dev, vo= id *arg) return rc; =20 cxled =3D to_cxl_endpoint_decoder(dev); - if (!cxled->dpa_res) - return rc; =20 - cxlmd =3D cxled_to_memdev(cxled); - cxlds =3D cxlmd->cxlds; - mode =3D cxlds->part[cxled->part].mode; + if (cxled->dpa_res) { + cxlmd =3D cxled_to_memdev(cxled); + cxlds =3D cxlmd->cxlds; + mode =3D cxlds->part[cxled->part].mode; + + if (cxled->skip) { + offset =3D cxled->dpa_res->start - cxled->skip; + length =3D cxled->skip; + rc =3D cxl_mem_get_poison(cxlmd, offset, length, NULL); + if (rc =3D=3D -EFAULT && mode =3D=3D CXL_PARTMODE_RAM) + rc =3D 0; + if (rc) + return rc; + } =20 - if (cxled->skip) { - offset =3D cxled->dpa_res->start - cxled->skip; - length =3D cxled->skip; - rc =3D cxl_mem_get_poison(cxlmd, offset, length, NULL); + offset =3D cxled->dpa_res->start; + length =3D cxled->dpa_res->end - offset + 1; + rc =3D cxl_mem_get_poison(cxlmd, offset, length, cxled->cxld.region); if (rc =3D=3D -EFAULT && mode =3D=3D CXL_PARTMODE_RAM) rc =3D 0; if (rc) return rc; - } =20 - offset =3D cxled->dpa_res->start; - length =3D cxled->dpa_res->end - offset + 1; 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charset="utf-8" The kernel now allows committed HDM decoders of zero size so BIOS can burn slots with LOCK, cxl_test needs to exercise the patch. Add a mock_zero_size_decoders module param, When set, the special endpoint under host-bridge0 (cxl_mem.0 and cxl_mem.4) commit decoders 1 and 2 as zero-size + locked above the decoder[0] auto-region, mirrored on the parent switch and host bridge. commit_end then lands on a decoder with no DPA resource, exercising the new enumeration and poison-by-endpoint paths. Signed-off-by: Vishal Aslot Signed-off-by: Richard Cheng --- v2->v3: - Gate the zero-size + locked decoder injection behind a new mock_zero_size_decoders module parameter (default off). v2 applied it unconditionally on the host-bridge0 auto-region endpoints, which the region test suite reuses, regressing 7 of 17 cxl unit tests; defaulting off leaves the shared topology untouched. v1->v2: - Replace second_decoder(), third_decoder() with a single match_decoder_by_index() helper, so all lookups share one matcher. - Use DEFINE_RANGE() for the empty range instead of an open-coded struct. - Set cxled->state =3D CXL_DECODER_STATE_MANUAL rather than STATE_AUT= O. - Set CXL_DECODER_F_LOCK on the mock zero-size decoders to model the BIOS-burns-slots case. --- tools/testing/cxl/test/cxl.c | 83 +++++++++++++++++++++++++++++++++--- 1 file changed, 77 insertions(+), 6 deletions(-) diff --git a/tools/testing/cxl/test/cxl.c b/tools/testing/cxl/test/cxl.c index 296516eecfd6..190cb18d6932 100644 --- a/tools/testing/cxl/test/cxl.c +++ b/tools/testing/cxl/test/cxl.c @@ -17,6 +17,7 @@ static int interleave_arithmetic; static bool extended_linear_cache; static bool fail_autoassemble; +static bool mock_zero_size_decoders; =20 #define FAKE_QTG_ID 42 =20 @@ -1041,16 +1042,47 @@ static void default_mock_decoder(struct cxl_decoder= *cxld) WARN_ON_ONCE(!cxld_registry_new(cxld)); } =20 -static int first_decoder(struct device *dev, const void *data) +static int match_decoder_by_index(struct device *dev, const void *data) { + int target_id =3D *(const int *)data; struct cxl_decoder *cxld; =20 if (!is_switch_decoder(dev)) return 0; cxld =3D to_cxl_decoder(dev); - if (cxld->id =3D=3D 0) - return 1; - return 0; + return cxld->id =3D=3D target_id; +} + +/* + * Mock a BIOS-burnt slot: a committed, locked, zero-size decoder + * (CXL r3.2 8.2.4.20.12). Gated by the mock_zero_size_decoders module + * param so the default cxl_test topology, shared by the region test + * suite, is left undisturbed. + */ +static void size_zero_mock_decoder_ep(struct cxl_decoder *cxld, u64 base) +{ + struct cxl_endpoint_decoder *cxled =3D to_cxl_endpoint_decoder(&cxld->dev= ); + + cxld->hpa_range =3D DEFINE_RANGE(base, base - 1); + cxld->interleave_ways =3D 2; + cxld->interleave_granularity =3D 4096; + cxld->target_type =3D CXL_DECODER_HOSTONLYMEM; + cxld->flags =3D CXL_DECODER_F_ENABLE | CXL_DECODER_F_LOCK; + cxled->state =3D CXL_DECODER_STATE_MANUAL; + cxld->commit =3D mock_decoder_commit; + cxld->reset =3D mock_decoder_reset; +} + +static void size_zero_mock_decoder_sw(struct cxl_decoder *cxld, u64 base, + int level) +{ + cxld->flags =3D CXL_DECODER_F_ENABLE | CXL_DECODER_F_LOCK; + cxld->target_type =3D CXL_DECODER_HOSTONLYMEM; + cxld->interleave_ways =3D level =3D=3D 0 ? 2 : 1; + cxld->interleave_granularity =3D 4096; + cxld->hpa_range =3D DEFINE_RANGE(base, base - 1); + cxld->commit =3D mock_decoder_commit; + cxld->reset =3D mock_decoder_reset; } =20 /* @@ -1131,7 +1163,7 @@ static bool mock_init_hdm_decoder(struct cxl_decoder = *cxld) * See 'cxl list -BMPu -m cxl_mem.0,cxl_mem.4' */ if (!is_endpoint_decoder(&cxld->dev) || !hb0 || pdev->id % 4 || - pdev->id > 4 || cxld->id > 0) { + pdev->id > 4 || cxld->id > (mock_zero_size_decoders ? 2 : 0)) { default_mock_decoder(cxld); return false; } @@ -1145,6 +1177,20 @@ static bool mock_init_hdm_decoder(struct cxl_decoder= *cxld) base =3D window->base_hpa; if (extended_linear_cache) base +=3D mock_auto_region_size; + + /* + * With mock_zero_size_decoders, decoders 1 and 2 of the special + * endpoints mock BIOS-burnt zero-size + locked slots above the + * decoder[0] auto-region (CXL r3.2 8.2.4.20.12). commit_end then + * points at a decoder with no DPA resource, exercising the + * zero-size enumeration and poison-by-endpoint code paths. + */ + if (cxld->id =3D=3D 1 || cxld->id =3D=3D 2) { + size_zero_mock_decoder_ep(cxld, base); + port->commit_end =3D cxld->id; + WARN_ON_ONCE(!cxld_registry_new(cxld)); + return false; + } cxld->hpa_range =3D (struct range) { .start =3D base, .end =3D base + mock_auto_region_size - 1, @@ -1168,9 +1214,11 @@ static bool mock_init_hdm_decoder(struct cxl_decoder= *cxld) */ iter =3D port; for (i =3D 0; i < 2; i++) { + int id =3D 0; + dport =3D iter->parent_dport; iter =3D dport->port; - dev =3D device_find_child(&iter->dev, NULL, first_decoder); + dev =3D device_find_child(&iter->dev, &id, match_decoder_by_index); /* * Ancestor ports are guaranteed to be enumerated before * @port, and all ports have at least one decoder. @@ -1214,6 +1262,26 @@ static bool mock_init_hdm_decoder(struct cxl_decoder= *cxld) =20 cxld_registry_update(cxld); put_device(dev); + + if (!mock_zero_size_decoders) + continue; + + /* + * Mirror the endpoint: commit the next two switch decoders + * as zero-size + locked so the burnt-slot layout extends + * end-to-end through the switch and host bridge. + */ + for (id =3D 1; id <=3D 2; id++) { + dev =3D device_find_child(&iter->dev, &id, + match_decoder_by_index); + if (WARN_ON(!dev)) + continue; + cxld =3D to_cxl_decoder(dev); + size_zero_mock_decoder_sw(cxld, base, i); + iter->commit_end =3D id; + cxld_registry_update(cxld); + put_device(dev); + } } =20 return false; @@ -2030,6 +2098,9 @@ module_param(extended_linear_cache, bool, 0444); MODULE_PARM_DESC(extended_linear_cache, "Enable extended linear cache supp= ort"); module_param(fail_autoassemble, bool, 0444); MODULE_PARM_DESC(fail_autoassemble, "Simulate missing member of an auto-re= gion"); +module_param(mock_zero_size_decoders, bool, 0444); +MODULE_PARM_DESC(mock_zero_size_decoders, + "Mock BIOS-burnt committed zero-size locked decoders under host-bridge0= "); module_init(cxl_test_init); module_exit(cxl_test_exit); MODULE_LICENSE("GPL v2"); --=20 2.43.0