From: Alison Schofield <alison.schofield@intel.com>

Commit fd49f99c1809 ("ACPI: NUMA: Add a node and memblk for each
CFMWS not in SRAT") did not account for the case where the BIOS
only partially describes a CFMWS Window in the SRAT. That means
the omitted address ranges, of a partially described CFMWS Window,
do not get assigned to a NUMA node.

Replace the call to phys_to_target_node() with numa_add_memblks().
Numa_add_memblks() searches an HPA range for existing memblk(s)
and extends those memblk(s) to fill the entire CFMWS Window.

Extending the existing memblks is a simple strategy that reuses
SRAT defined proximity domains from part of a window to fill out
the entire window, based on the knowledge* that all of a CFMWS
window is of a similar performance class.

*Note that this heuristic will evolve when CFMWS Windows present
a wider range of characteristics. The extension of the proximity
domain, implemented here, is likely a step in developing a more
sophisticated performance profile in the future.

There is no change in behavior when the SRAT does not describe
the CFMWS Window at all. In that case, a new NUMA node with a
single memblk covering the entire CFMWS Window is created.

Fixes: fd49f99c1809 ("ACPI: NUMA: Add a node and memblk for each CFMWS not in SRAT")
Reported-by: Derick Marks <derick.w.marks@intel.com>
Suggested-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Alison Schofield <alison.schofield@intel.com>
Tested-by: Derick Marks <derick.w.marks@intel.com>
---
 drivers/acpi/numa/srat.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/acpi/numa/srat.c b/drivers/acpi/numa/srat.c
index 1f4fc5f8a819..12f330b0eac0 100644
--- a/drivers/acpi/numa/srat.c
+++ b/drivers/acpi/numa/srat.c
@@ -310,11 +310,16 @@ static int __init acpi_parse_cfmws(union acpi_subtable_headers *header,
 	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)
+	/*
+	 * The SRAT may have already described NUMA details for all,
+	 * or a portion of, this CFMWS HPA range. Extend the memblks
+	 * found for any portion of the window to cover the entire
+	 * window.
+	 */
+	if (!numa_fill_memblks(start, end))
 		return 0;
 
+	/* No SRAT description. Create a new node. */
 	node = acpi_map_pxm_to_node(*fake_pxm);
 
 	if (node == NUMA_NO_NODE) {
-- 
2.37.3

alison.schofield@ wrote:
> From: Alison Schofield <alison.schofield@intel.com>
> 
> Commit fd49f99c1809 ("ACPI: NUMA: Add a node and memblk for each
> CFMWS not in SRAT") did not account for the case where the BIOS
> only partially describes a CFMWS Window in the SRAT. That means
> the omitted address ranges, of a partially described CFMWS Window,
> do not get assigned to a NUMA node.
> 
> Replace the call to phys_to_target_node() with numa_add_memblks().
> Numa_add_memblks() searches an HPA range for existing memblk(s)
> and extends those memblk(s) to fill the entire CFMWS Window.
> 
> Extending the existing memblks is a simple strategy that reuses
> SRAT defined proximity domains from part of a window to fill out
> the entire window, based on the knowledge* that all of a CFMWS
> window is of a similar performance class.
> 
> *Note that this heuristic will evolve when CFMWS Windows present
> a wider range of characteristics. The extension of the proximity
> domain, implemented here, is likely a step in developing a more
> sophisticated performance profile in the future.
> 
> There is no change in behavior when the SRAT does not describe
> the CFMWS Window at all. In that case, a new NUMA node with a
> single memblk covering the entire CFMWS Window is created.
> 
> Fixes: fd49f99c1809 ("ACPI: NUMA: Add a node and memblk for each CFMWS not in SRAT")
> Reported-by: Derick Marks <derick.w.marks@intel.com>
> Suggested-by: Dan Williams <dan.j.williams@intel.com>
> Signed-off-by: Alison Schofield <alison.schofield@intel.com>
> Tested-by: Derick Marks <derick.w.marks@intel.com>

Reviewed-by: Dan Williams <dan.j.williams@intel.com>

On 7/10/23 13:02, alison.schofield@intel.com wrote:
> +	/*
> +	 * The SRAT may have already described NUMA details for all,
> +	 * or a portion of, this CFMWS HPA range. Extend the memblks
> +	 * found for any portion of the window to cover the entire
> +	 * window.
> +	 */
> +	if (!numa_fill_memblks(start, end))
>  		return 0;

FWIW, the pieces didn't really fit together for me for this pair of
patches until I read *this* comment.

Either way:

Acked-by: Dave Hansen <dave.hansen@linux.intel.com>