linux-kernel - Re: [PATCH v6 13/14] arm64, acpi, numa: NUMA support based on SRAT and SLIT

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Message-ID: <20160512094915.GD11226@e104818-lin.cambridge.arm.com>
Date:	Thu, 12 May 2016 10:49:16 +0100
From:	Catalin Marinas <catalin.marinas@....com>
To:	David Daney <ddaney@...iumnetworks.com>
Cc:	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Mark Rutland <mark.rutland@....com>,
	linux-ia64@...r.kernel.org, David Daney <david.daney@...ium.com>,
	Will Deacon <will.deacon@....com>,
	Lv Zheng <lv.zheng@...el.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Frank Rowand <frowand.list@...il.com>, x86@...nel.org,
	Robert Moore <robert.moore@...el.com>,
	linux-acpi@...r.kernel.org, Ingo Molnar <mingo@...hat.com>,
	Grant Likely <grant.likely@...aro.org>,
	Len Brown <lenb@...nel.org>, Fenghua Yu <fenghua.yu@...el.com>,
	Marc Zyngier <Marc.Zyngier@....com>,
	Jon Masters <jcm@...hat.com>,
	Robert Richter <rrichter@...ium.com>,
	Rob Herring <robh+dt@...nel.org>,
	David Daney <ddaney.cavm@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-arm-kernel@...ts.infradead.org, devel@...ica.org,
	Tony Luck <tony.luck@...el.com>, linux-kernel@...r.kernel.org,
	Hanjun Guo <hanjun.guo@...aro.org>,
	Ganapatrao Kulkarni <gkulkarni@...iumnetworks.com>
Subject: Re: [PATCH v6 13/14] arm64, acpi, numa: NUMA support based on SRAT
 and SLIT

On Wed, May 11, 2016 at 05:06:13PM -0700, David Daney wrote:
> On 05/11/2016 03:39 AM, Catalin Marinas wrote:
> >On Wed, Apr 27, 2016 at 11:07:15AM -0700, David Daney wrote:
> >>+static int __init get_mpidr_in_madt(int acpi_id, u64 *mpidr)
> >>+{
> >>+	unsigned long madt_end, entry;
> >>+	struct acpi_table_madt *madt;
> >>+	acpi_size tbl_size;
> >>+
> >>+	if (ACPI_FAILURE(acpi_get_table_with_size(ACPI_SIG_MADT, 0,
> >>+			(struct acpi_table_header **)&madt, &tbl_size)))
> >>+		return -ENODEV;
> >>+
> >>+	entry = (unsigned long)madt;
> >>+	madt_end = entry + madt->header.length;
> >>+
> >>+	/* Parse all entries looking for a match. */
> >>+	entry += sizeof(struct acpi_table_madt);
> >>+	while (entry + sizeof(struct acpi_subtable_header) < madt_end) {
> >>+		struct acpi_subtable_header *header =
> >>+			(struct acpi_subtable_header *)entry;
> >>+
> >>+		if (header->type == ACPI_MADT_TYPE_GENERIC_INTERRUPT) {
> >>+			struct acpi_madt_generic_interrupt *gicc =
> >>+				container_of(header,
> >>+				struct acpi_madt_generic_interrupt, header);
> >>+
> >>+			if ((gicc->flags & ACPI_MADT_ENABLED) &&
> >>+			    (gicc->uid == acpi_id)) {
> >>+				*mpidr = gicc->arm_mpidr;
> >>+				early_acpi_os_unmap_memory(madt, tbl_size);
> >>+				return 0;
> >>+			}
> >>+		}
> >>+		entry += header->length;
> >>+	}
> >>+
> >>+	early_acpi_os_unmap_memory(madt, tbl_size);
> >>+	return -ENODEV;
> >>+}
> >>+
> >>+/* Callback for Proximity Domain -> ACPI processor UID mapping */
> >>+void __init acpi_numa_gicc_affinity_init(struct acpi_srat_gicc_affinity *pa)
> >>+{
> >>+	int pxm, node;
> >>+	u64 mpidr;
> >>+
> >>+	if (srat_disabled())
> >>+		return;
> >>+
> >>+	if (pa->header.length < sizeof(struct acpi_srat_gicc_affinity)) {
> >>+		pr_err("SRAT: Invalid SRAT header length: %d\n",
> >>+			pa->header.length);
> >>+		bad_srat();
> >>+		return;
> >>+	}
> >>+
> >>+	if (!(pa->flags & ACPI_SRAT_GICC_ENABLED))
> >>+		return;
> >>+
> >>+	if (cpus_in_srat >= NR_CPUS) {
> >>+		pr_warn_once("SRAT: cpu_to_node_map[%d] is too small, may not be able to use all cpus\n",
> >>+			     NR_CPUS);
> >>+		return;
> >>+	}
> >>+
> >>+	pxm = pa->proximity_domain;
> >>+	node = acpi_map_pxm_to_node(pxm);
> >>+
> >>+	if (node == NUMA_NO_NODE || node >= MAX_NUMNODES) {
> >>+		pr_err("SRAT: Too many proximity domains %d\n", pxm);
> >>+		bad_srat();
> >>+		return;
> >>+	}
> >>+
> >>+	if (get_mpidr_in_madt(pa->acpi_processor_uid, &mpidr)) {
> >>+		pr_err("SRAT: PXM %d with ACPI ID %d has no valid MPIDR in MADT\n",
> >>+			pxm, pa->acpi_processor_uid);
> >>+		bad_srat();
> >>+		return;
> >>+	}
> >
> >I wonder whether you could replace the get_mpidr_in_madt() function with
> >something like acpi_get_phys_id(). It looks like get_mpidr_in_madt()
> >duplicates functionality already available elsewhere.
> 
> I just tried that, and it doesn't work.
> 
> The problem is that this code is being run very early in the boot, and
> kmalloc cannot be used.  acpi_get_phys_id() and its ilk can only be used
> once we have working kmalloc.  We need to extract the NUMA information early
> like this precisely because it is needed to initializing the slab system
> 
> Notice that we are using early_acpi_os_unmap_memory() et al. in
> get_mpidr_in_madt() explicitly for this reason.
> 
> In summary: I don't think we need another revision of this patch, it is like
> this for a good reason.

Slightly confusing, in another reply you said you are going to address
my comment. So, is it doable?

-- 
Catalin