Re: [PATCH v9 4/6] ACPI: HMAT: Fix handling of changes from ACPI 6.2 to ACPI 6.3

From: Bjorn Helgaas <helgaas@kernel.org>
To: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: linux-mm@kvack.org, linux-acpi@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, x86@kernel.org,
	Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
	Bjorn Helgaas <bhelgaas@google.com>,
	rafael@kernel.org, linux-kernel@vger.kernel.org,
	Ingo Molnar <mingo@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	linuxarm@huawei.com, Dan Williams <dan.j.williams@intel.com>,
	Brice Goglin <Brice.Goglin@inria.fr>,
	Sean V Kelley <sean.v.kelley@linux.intel.com>,
	linux-api@vger.kernel.org
Subject: Re: [PATCH v9 4/6] ACPI: HMAT: Fix handling of changes from ACPI 6.2 to ACPI 6.3
Date: Thu, 20 Aug 2020 17:21:29 -0500	[thread overview]
Message-ID: <20200820222129.GA1571389@bjorn-Precision-5520> (raw)
In-Reply-To: <20200819145111.1715026-5-Jonathan.Cameron@huawei.com>

On Wed, Aug 19, 2020 at 10:51:09PM +0800, Jonathan Cameron wrote:
> In ACPI 6.3, the Memory Proximity Domain Attributes Structure
> changed substantially.  One of those changes was that the flag
> for "Memory Proximity Domain field is valid" was deprecated.
> 
> This was because the field "Proximity Domain for the Memory"
> became a required field and hence having a validity flag makes
> no sense.
> 
> So the correct logic is to always assume the field is there.
> Current code assumes it never is.
> 
> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> ---
>  drivers/acpi/numa/hmat.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/acpi/numa/hmat.c b/drivers/acpi/numa/hmat.c
> index 2c32cfb72370..07cfe50136e0 100644
> --- a/drivers/acpi/numa/hmat.c
> +++ b/drivers/acpi/numa/hmat.c
> @@ -424,7 +424,7 @@ static int __init hmat_parse_proximity_domain(union acpi_subtable_headers *heade
>  		pr_info("HMAT: Memory Flags:%04x Processor Domain:%u Memory Domain:%u\n",
>  			p->flags, p->processor_PD, p->memory_PD);
>  
> -	if (p->flags & ACPI_HMAT_MEMORY_PD_VALID && hmat_revision == 1) {
> +	if ((p->flags & ACPI_HMAT_MEMORY_PD_VALID && hmat_revision == 1) || hmat_revision == 2) {

I hope/assume the spec is written in such a way that p->memory_PD is
required for any revision > 1?  So maybe this should be:

  if ((p->flags & ACPI_HMAT_MEMORY_PD_VALID && hmat_revision == 1) ||
      hmat_revision > 1) {

>  		target = find_mem_target(p->memory_PD);
>  		if (!target) {
>  			pr_debug("HMAT: Memory Domain missing from SRAT\n");
> -- 
> 2.19.1
> 