linux-kernel - Re: [PATCH v5 3/3] acpi,srat: give memory block size advice based on CFMWS alignment

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Message-ID: <ZyT7ttLG-_eGMDmx@kernel.org>
Date: Fri, 1 Nov 2024 18:03:02 +0200
From: Mike Rapoport <rppt@...nel.org>
To: Gregory Price <gourry@...rry.net>
Cc: x86@...nel.org, linux-kernel@...r.kernel.org,
	linux-acpi@...r.kernel.org, linux-mm@...ck.org,
	linux-cxl@...r.kernel.org, Jonathan.Cameron@...wei.com,
	dan.j.williams@...el.com, rrichter@....com, Terry.Bowman@....com,
	dave.jiang@...el.com, ira.weiny@...el.com,
	alison.schofield@...el.com, dave.hansen@...ux.intel.com,
	luto@...nel.org, peterz@...radead.org, tglx@...utronix.de,
	mingo@...hat.com, bp@...en8.de, hpa@...or.com, rafael@...nel.org,
	lenb@...nel.org, david@...hat.com, osalvador@...e.de,
	gregkh@...uxfoundation.org, akpm@...ux-foundation.org
Subject: Re: [PATCH v5 3/3] acpi,srat: give memory block size advice based on
 CFMWS alignment

On Fri, Nov 01, 2024 at 09:47:05AM -0400, Gregory Price wrote:
> Capacity is stranded when CFMWS regions are not aligned to block size.
> On x86, block size increases with capacity (2G blocks @ 64G capacity).
> 
> Use CFMWS base/size to report memory block size alignment advice.
> 
> Suggested-by: Dan Williams <dan.j.williams@...el.com>
> Signed-off-by: Gregory Price <gourry@...rry.net>

Acked-by: Mike Rapoport (Microsoft) <rppt@...nel.org>

> ---
>  drivers/acpi/numa/srat.c | 12 +++++++++++-
>  1 file changed, 11 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/acpi/numa/srat.c b/drivers/acpi/numa/srat.c
> index 44f91f2c6c5d..34b6993e7d6c 100644
> --- a/drivers/acpi/numa/srat.c
> +++ b/drivers/acpi/numa/srat.c
> @@ -14,6 +14,7 @@
>  #include <linux/errno.h>
>  #include <linux/acpi.h>
>  #include <linux/memblock.h>
> +#include <linux/memory.h>
>  #include <linux/numa.h>
>  #include <linux/nodemask.h>
>  #include <linux/topology.h>
> @@ -338,13 +339,22 @@ static int __init acpi_parse_cfmws(union acpi_subtable_headers *header,
>  {
>  	struct acpi_cedt_cfmws *cfmws;
>  	int *fake_pxm = arg;
> -	u64 start, end;
> +	u64 start, end, align;
>  	int node;
>  
>  	cfmws = (struct acpi_cedt_cfmws *)header;
>  	start = cfmws->base_hpa;
>  	end = cfmws->base_hpa + cfmws->window_size;
>  
> +	/* Align memblock size to CFMW regions if possible */
> +	align = 1UL << __ffs(start | end);
> +	if (align >= SZ_256M) {
> +		if (memory_block_advise_max_size(align) < 0)
> +			pr_warn("CFMWS: memblock size advise failed\n");
> +	} else {
> +		pr_err("CFMWS: [BIOS BUG] base/size alignment violates spec\n");
> +	}
> +
>  	/*
>  	 * The SRAT may have already described NUMA details for all,
>  	 * or a portion of, this CFMWS HPA range. Extend the memblks
> -- 
> 2.43.0
> 
> 

-- 
Sincerely yours,
Mike.