On Mon, Oct 25, 2021 at 07:47:32PM -0700, Dan Williams wrote: > On Mon, Oct 18, 2021 at 10:01 PM <alison.schofield@xxxxxxxxx> wrote: > > > > From: Alison Schofield <alison.schofield@xxxxxxxxx> > > > > During NUMA init, CXL memory defined in the SRAT Memory Affinity > > subtable may be assigned to a NUMA node. Since there is no > > requirement that the SRAT be comprehensive for CXL memory another > > mechanism is needed to assign NUMA nodes to CXL memory not identified > > in the SRAT. > > > > Use the CXL Fixed Memory Window Structure (CFMWS) of the ACPI CXL > > Early Discovery Table (CEDT) to find all CXL memory ranges. > > Create a NUMA node for each CFMWS that is not already assigned to > > a NUMA node. Add a memblk attaching its host physical address > > range to the node. > > > > Note that these ranges may not actually map any memory at boot time. > > They may describe persistent capacity or may be present to enable > > hot-plug. > > > > Consumers can use phys_to_target_node() to discover the NUMA node. > > > > Signed-off-by: Alison Schofield <alison.schofield@xxxxxxxxx> > > --- The next version of this patch is now included in this patchset that adds helpers for parsing the CEDT subtables: https://lore.kernel.org/linux-cxl/163553711933.2509508.2203471175679990.stgit@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/T/#mf40d84e1ad4c01f69f794d591b07774255993185 It addresses Dan's comments below. >> snip > > +{ > > + struct acpi_cedt_cfmws *cfmws; > > + acpi_size len, cur = 0; > > + int i, node, pxm = 0; > > Shouldn't this be -1, on the idea that the first numa node to assign > if none are set is zero? > > I don't think the way you have it is a problem in practice because > SRAT should always be there in a NUMA system. However, the first CFMWS > pxm should start after the last SRAT entry, or 0 if no SRAT entries. > > > + void *cedt_subtable; > > + u64 start, end; > > + > > + /* Find the max PXM defined in the SRAT */ > > + for (i = 0; i < MAX_NUMNODES - 1; i++) { > > How about: > > for (i = 0, pxm = -1; i < MAX_NUMNODES -1; i++) > > ...just to keep the initialization close to the use, but that's just a > personal style preference. Done. > > > + if (node_to_pxm_map[i] > pxm) > > + pxm = node_to_pxm_map[i]; > > + } > > + /* Start assigning fake PXM values after the SRAT max PXM */ > > + pxm++; > > + > > + len = acpi_cedt->length - sizeof(*acpi_cedt); > > + cedt_subtable = acpi_cedt + 1; > > + > > + while (cur < len) { > > Similarly to above I wonder if this would be cleaner as a for loop > then you could use typical "continue" statements rather than goto. I > took a stab at creating a for_each_cedt() helper which ended up a > decent cleanup for drivers/cxl/ > > drivers/cxl/acpi.c | 48 +++++++++++++++--------------------------------- > 1 file changed, 15 insertions(+), 33 deletions(-) > > ...however, I just realized this NUMA code is running at init time, so > it can just use the acpi_table_parse_entries_array() helper to walk > the CFMWS like the othe subtable walkers in acpi_numa_init(). You > would need to update the subtable helpers (acpi_get_subtable_type() et > al) to recognize the CEDT case. > > [ Side note for the implications of acpi_table_parse_entries_array() > for drivers/cxl/acpi.c ] > > Rafael, both the NFIT driver and now the CXL ACPI driver have open > coded subtable parsing. Any philosophical reason to keep the subtable > parsing code as __init? It can still be __init and thrown away if > those drivers are not build-time enabled. > The updated patch (in the greater patchset) now uses the new helpers. > snip > > + node = acpi_map_pxm_to_node(pxm); > > + if (node == NUMA_NO_NODE) { > > + pr_err("ACPI NUMA: Too many proximity domains.\n"); > > I would add "while processing CFMWS" to make it clear that the BIOS > technically did not declare too many PXMs; it was the Linux heuristic > for opportunistically emulating more PXMs. > Done. > > snip > > } > > diff --git a/include/linux/acpi.h b/include/linux/acpi.h > > index 974d497a897d..f837fd715440 100644 > > --- a/include/linux/acpi.h > > +++ b/include/linux/acpi.h > > @@ -426,6 +426,7 @@ extern bool acpi_osi_is_win8(void); > > #ifdef CONFIG_ACPI_NUMA > > int acpi_map_pxm_to_node(int pxm); > > int acpi_get_node(acpi_handle handle); > > +int __init numa_add_memblk(int nodeid, u64 start, u64 end); > > This doesn't belong here. > > There is already a declaration for this in > arch/x86/include/asm/numa.h. I think what you are missing is that your > new code needs to be within the same ifdef guards as the other helpers > in srat.c that call numa_add_memblk(). See the line that has: > > #if defined(CONFIG_X86) || defined(CONFIG_ARM64) || defined(CONFIG_LOONGARCH) > > ...above acpi_numa_slit_init() Done.
