On Wed, Oct 20, 2021 at 5:26 PM Rafael J. Wysocki <rafael@xxxxxxxxxx> wrote:
>
> On Tue, Oct 19, 2021 at 7:01 AM <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>
>
> Dan, this seems to fall into your territory.
>
> > ---
> > Changes in v3:
> > - Initial variable pxm (Ben)
> >
> > Changes in v2:
> > - Use MAX_NUMNODES as max value when searching node_to_pxm_map() (0-day)
> > - Add braces around single statement for loop (coding style)
> > - Rename acpi_parse_cfmws() to acpi_cxl_cfmws_init to be more like other
> > functions in this file doing similar work.
> > - Comments: remove superflous and state importance of the init order,
> > CFMWS after SRAT, (Ira, Dan)
> > - Add prototype for numa_add_memblk() (0-day)
> >
> > drivers/acpi/numa/srat.c | 70 ++++++++++++++++++++++++++++++++++++++++
> > drivers/cxl/acpi.c | 8 +++--
> > include/linux/acpi.h | 1 +
> > 3 files changed, 76 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/acpi/numa/srat.c b/drivers/acpi/numa/srat.c
> > index b8795fc49097..daaaef58f1e6 100644
> > --- a/drivers/acpi/numa/srat.c
> > +++ b/drivers/acpi/numa/srat.c
> > @@ -300,6 +300,67 @@ acpi_numa_memory_affinity_init(struct acpi_srat_mem_affinity *ma)
> > }
> > #endif /* defined(CONFIG_X86) || defined (CONFIG_ARM64) */
> >
> > +static int __init acpi_cxl_cfmws_init(struct acpi_table_header *acpi_cedt)
> > +{
> > + struct acpi_cedt_cfmws *cfmws;
> > + acpi_size len, cur = 0;
> > + int i, node, pxm = 0;
> > + void *cedt_subtable;
> > + u64 start, end;
> > +
> > + /* Find the max PXM defined in the SRAT */
> > + for (i = 0; i < MAX_NUMNODES - 1; i++) {
> > + 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) {
> > + struct acpi_cedt_header *c = cedt_subtable + cur;
> > +
> > + if (c->type != ACPI_CEDT_TYPE_CFMWS)
> > + goto next;
> > +
> > + cfmws = cedt_subtable + cur;
> > + if (cfmws->header.length < sizeof(*cfmws)) {
> > + pr_warn_once("CFMWS entry skipped:invalid length:%u\n",
> > + cfmws->header.length);
> > + goto next;
> > + }
> > +
> > + start = cfmws->base_hpa;
> > + end = cfmws->base_hpa + cfmws->window_size;
> > +
> > + /*
> > + * Skip if the SRAT already described
> > + * the NUMA details for this HPA.
> > + */
> > + node = phys_to_target_node(start);
> > + if (node != NUMA_NO_NODE)
> > + goto next;
> > +
> > + node = acpi_map_pxm_to_node(pxm);
> > + if (node == NUMA_NO_NODE) {
> > + pr_err("ACPI NUMA: Too many proximity domains.\n");
> > + return -EINVAL;
> > + }
> > +
> > + if (numa_add_memblk(node, start, end) < 0) {
> > + /* CXL driver must handle the NUMA_NO_NODE case */
> > + pr_warn("ACPI NUMA: Failed to add memblk for CFMWS node %d [mem %#llx-%#llx]\n",
> > + node, start, end);
> > + }
> > + pxm++;
> > +next:
> > + cur += c->length;
> > + }
> > + return 0;
> > +}
> > +
> > static int __init acpi_parse_slit(struct acpi_table_header *table)
> > {
> > struct acpi_table_slit *slit = (struct acpi_table_slit *)table;
> > @@ -478,6 +539,15 @@ int __init acpi_numa_init(void)
> > /* SLIT: System Locality Information Table */
> > acpi_table_parse(ACPI_SIG_SLIT, acpi_parse_slit);
> >
> > + /*
> > + * CEDT: CXL Fixed Memory Window Structures (CFMWS)
> > + * must be parsed after the SRAT. It creates NUMA
> > + * Nodes for CXL memory ranges not already defined
> > + * in the SRAT and it assigns PXMs after the max PXM
> > + * defined in the SRAT.
> > + */
> > + acpi_table_parse(ACPI_SIG_CEDT, acpi_cxl_cfmws_init);
>
> acpi_table_parse() creates a memory mapping for accessing the table.
> so it usually is good to call acpi_put_table() when you are done with
> it to let that mapping go away.
Sorry, this isn't right. acpi_table_parse() calls acpi_put_table() by
itself, so scratch the above.
