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envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=2607:f8b0:4864:20::741; envelope-from=gourry.memverge@gmail.com; helo=mail-qk1-x741.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Qemu-devel" Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @gmail.com) X-ZM-MESSAGEID: 1666818300936100003 Content-Type: text/plain; charset="utf-8" Early-boot e820 records will be inserted by the bios/efi/early boot software and be reported to the kernel via insert_resource. Later, when CXL drivers iterate through the regions again, they will insert another resource and make the RESERVED memory area a child. This RESERVED memory area causes the memory region to become unusable, and as a result attempting to create memory regions with `cxl create-region ...` Will fail due to the RESERVED area intersecting with the CXL window. During boot the following traceback is observed: 0xffffffff81101650 in insert_resource_expand_to_fit () 0xffffffff83d964c5 in e820__reserve_resources_late () 0xffffffff83e03210 in pcibios_resource_survey () 0xffffffff83e04f4a in pcibios_init () Which produces a call to reserve the CFMWS area: (gdb) p *new $54 =3D {start =3D 0x290000000, end =3D 0x2cfffffff, name =3D "Reserved", flags =3D 0x200, desc =3D 0x7, parent =3D 0x0, sibling =3D 0x0, child =3D 0x0} Later the Kernel parses ACPI tables and reserves the exact same area as the CXL Fixed Memory Window: 0xffffffff811016a4 in insert_resource_conflict () insert_resource () 0xffffffff81a81389 in cxl_parse_cfmws () 0xffffffff818c4a81 in call_handler () acpi_parse_entries_array () (gdb) p/x *new $59 =3D {start =3D 0x290000000, end =3D 0x2cfffffff, name =3D "CXL Window 0= ", flags =3D 0x200, desc =3D 0x0, parent =3D 0x0, sibling =3D 0x0, child =3D 0x0} This produces the following output in /proc/iomem: 590000000-68fffffff : CXL Window 0 590000000-68fffffff : Reserved This reserved area causes `get_free_mem_region()` to fail due to a check against `__region_intersects()`. Due to this reserved area, the intersect check will only ever return REGION_INTERSECTS, which causes `cxl create-region` to always fail. Signed-off-by: Gregory Price Acked-by: Jonathan Cameron --- hw/i386/pc.c | 2 -- 1 file changed, 2 deletions(-) diff --git a/hw/i386/pc.c b/hw/i386/pc.c index 768982ae9a..203c90fedb 100644 --- a/hw/i386/pc.c +++ b/hw/i386/pc.c @@ -1062,7 +1062,6 @@ void pc_memory_init(PCMachineState *pcms, hwaddr cxl_size =3D MiB; =20 cxl_base =3D pc_get_cxl_range_start(pcms); - e820_add_entry(cxl_base, cxl_size, E820_RESERVED); memory_region_init(mr, OBJECT(machine), "cxl_host_reg", cxl_size); memory_region_add_subregion(system_memory, cxl_base, mr); cxl_resv_end =3D cxl_base + cxl_size; @@ -1078,7 +1077,6 @@ void pc_memory_init(PCMachineState *pcms, memory_region_init_io(&fw->mr, OBJECT(machine), &cfmws_ops= , fw, "cxl-fixed-memory-region", fw->size); memory_region_add_subregion(system_memory, fw->base, &fw->= mr); - e820_add_entry(fw->base, fw->size, E820_RESERVED); cxl_fmw_base +=3D fw->size; cxl_resv_end =3D cxl_fmw_base; } --=20 2.37.3