On Thu, Mar 13, 2025 at 02:09:07PM +0800, Yuquan Wang wrote:
> The absence of SRAT would cause the fake_pxm to be -1 and increment
> to 0, then send to acpi_parse_cfmws(). If there exists CXL memory
> ranges that are defined in the CFMWS and not already defined in the
> SRAT, the new node (node0) for the CXL memory would be invalid, as
> node0 is already in "used".
>
> This utilizes disable_srat() & srat_disabled() to fail CXL init.
Seems like this fixup has drifted from adjusting the fake_pxm to
shutting down CXL parsing. More below -
>
> Signed-off-by: Yuquan Wang <wangyuquan1236@xxxxxxxxxxxxxx>
> ---
>
> Changes in v2:
> - Add disable_srat() when fake_pxm is invalid
> - Add srat_disabled() check in cxl_acpi_probe() and acpi_parse_cfmws()
>
>
> drivers/acpi/numa/srat.c | 10 ++++++++++
> drivers/cxl/acpi.c | 4 ++++
> 2 files changed, 14 insertions(+)
>
> diff --git a/drivers/acpi/numa/srat.c b/drivers/acpi/numa/srat.c
> index 00ac0d7bb8c9..2dac25c9258a 100644
> --- a/drivers/acpi/numa/srat.c
> +++ b/drivers/acpi/numa/srat.c
> @@ -441,6 +441,11 @@ static int __init acpi_parse_cfmws(union acpi_subtable_headers *header,
> start = cfmws->base_hpa;
> end = cfmws->base_hpa + cfmws->window_size;
>
> + if (srat_disabled()) {
> + pr_err("SRAT is missing or bad while processing CFMWS.\n");
> + return -EINVAL;
> + }
> +
This goes too far by shutting down cfmws parsing for lack of SRAT.
> /*
> * The SRAT may have already described NUMA details for all,
> * or a portion of, this CFMWS HPA range. Extend the memblks
> @@ -646,6 +651,11 @@ int __init acpi_numa_init(void)
> if (node_to_pxm_map[i] > fake_pxm)
> fake_pxm = node_to_pxm_map[i];
> }
> +
> + /* Make sure CFMWs fake nodes start at node[1] */
> + if (fake_pxm < 0)
> + disable_srat();
> +
How does the code above make sure fake node starts at node[1]?
Would an explicit adjustment like this work?
- last_real_pxm = fake_pxm;
- fake_pxm++;
+ fake_pxm = max(fake_pxm, 1);
+ last_real_pxm = fake_pxm--;
> last_real_pxm = fake_pxm;
> fake_pxm++;
> acpi_table_parse_cedt(ACPI_CEDT_TYPE_CFMWS, acpi_parse_cfmws,
> diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
> index cb14829bb9be..e75a8ead99f6 100644
> --- a/drivers/cxl/acpi.c
> +++ b/drivers/cxl/acpi.c
> @@ -829,6 +829,10 @@ static int cxl_acpi_probe(struct platform_device *pdev)
> if (rc)
> return rc;
>
> + /* CXL must be in a NUMA system */
> + if (srat_disabled())
> + return -EINVAL;
> +
> cxl_res = devm_kzalloc(host, sizeof(*cxl_res), GFP_KERNEL);
> if (!cxl_res)
> return -ENOMEM;
> --
> 2.34.1
>
