Message-ID: <20200714203641.GA411640@bjorn-Precision-5520>
Date:   Tue, 14 Jul 2020 15:36:41 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Jonathan Cameron <Jonathan.Cameron@...wei.com>
Cc:     linux-mm@...ck.org, linux-acpi@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, x86@...nel.org,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Bjorn Helgaas <bhelgaas@...gle.com>, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org, martin@...nix.com,
        Ingo Molnar <mingo@...hat.com>, linux-ia64@...r.kernel.org,
        Tony Luck <tony.luck@...el.com>,
        Fenghua Yu <fenghua.yu@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>, linuxarm@...wei.com,
        Dan Williams <dan.j.williams@...el.com>
Subject: Re: [PATCH] ACPI: Only create numa nodes from entries in SRAT or
 SRAT emulation.

The subject suggests that currently we create NUMA nodes from SRAT
*and* other sources, and that this patch will remove the other
sources.  Is that right?

On Mon, Jul 13, 2020 at 11:10:18PM +0800, Jonathan Cameron wrote:
> Here, I will use the term Proximity Domains for the ACPI description and
> Numa Nodes for the in kernel representation.

ACPI spells it "NUMA".  Maybe in subject line, too.

> Until ACPI 6.3 it was arguably possible to interpret the specification as
> allowing _PXM in DSDT and similar to define additional Proximity Domains.

I *think* you mean that the SRAT defines proximity domains (ACPI v6.3,
sec 5.2.16) and the possible interpretation is that _PXM can define
new proximity domains that were not mentioned in the SRAT.

> The reality was that was never the intent, and a 'clarification' was added
> in ACPI 6.3 [1].  In practice I think the kernel has never allowed any other
> interpretaion, except possibly on adhoc base within some out of tree driver
> (using it very very carefully given potential to crash when using various
> standard calls such as devm_kzalloc).

Drop the "was never the intent" part; who knows what intent of the
cabal that wrote the spec was, and it isn't really useful anyway.  I'd
say the "Note" in 5.2.16 qualifies as a clarification and doesn't need
scare quotes around it.

s/interpretaion/interpretation/
s/adhoc/ad hoc/
s/base/basis/ (I guess?)

Personally I don't see the point of mentioning out-of-tree drivers
that might be doing something wrong unless it helps us maintain
*in-tree* stuff.

> Proximity Domains are always defined in SRAT.  In ACPI, there are methods
> defined in ACPI to allow their characteristics to be tweaked later but
> Proximity Domains have to be referenced in this table at boot, thus
> allowing Linux to instantiate relevant Numa Node data structures.

s/In ACPI, there/There/

> We ran into a problem when enabling _PXM handling for PCI devices and found
> there were boards out there advertising devices in proximity domains that
> didn't exist [2].
> 
> The fix suggested here is to modfiy the function acpi_map_pxm_to_node.
> This function is both used to create and lookup proximity domains.
> A parameter is added to specify whether it should create a new
> proximity domain when it encounters a Proximity Domain ID that it
> hasn't seen before.

s/modfiy/modify/

> Naturally there is a quirk.  For SRAT ITS entries on ARM64 the handling is
> done with an additional pass of SRAT, potentially later in the boot. We
> could modify that behaviour so we could identify the existence of Proximity
> Domains unique to the ITS structures, and handle them as a special case
> of a Genric Initiator (once support for those merges) however...

s/ITS/Interrupt Translation Service (ITS)/ (first time)
s/Genric/Generic/ (or maybe "generic initiator" as used in ACPI spec)

> Currently (5.8-rc2) setting the Proximity Domain of an ITS to one that hasn't
> been instantiated by being specified in another type of SRAT resource entry
> results in:

Are you saying the _PXM of an ITS mentions a proximity domain that
wasn't mentioned in the SRAT?

Or are you saying an SRAT ITS entry mentions a proximity domain that
wasn't mentioned in a different type of SRAT entry?  I *think* this is
what you're saying, but I don't see anything in the spec about which
entry types are allowed to define proximity domains.

> ITS [mem 0x202100000-0x20211ffff]
> ITS@...000000202100000: Using ITS number 0
> Unable to handle kernel paging request at virtual address 0000000000001a08
> Mem abort info:
> ESR = 0x96000004
> EC = 0x25: DABT (current EL), IL = 32 bits
> SET = 0, FnV = 0
> EA = 0, S1PTW = 0
> Data abort info:
> ISV = 0, ISS = 0x00000004
> CM = 0, WnR = 0
> [0000000000001a08] user address but active_mm is swapper
> Internal error: Oops: 96000004 [#1] PREEMPT SMP
> Modules linked in:
> CPU: 0 PID: 0 Comm: swapper/0 Tainted: G       A          5.8.0-rc2 #483
> pstate: 80000089 (Nzcv daIf -PAN -UAO BTYPE=--)
> pc : __alloc_pages_nodemask+0xe8/0x338
> lr : __alloc_pages_nodemask+0xc0/0x338
> sp : ffffa81540c139b0
> x29: ffffa81540c139b0 x28: 0000000000000001
> x27: 0000000000000100 x26: ffffa81540c1ad38
> x25: 0000000000000000 x24: 0000000000000000
> x23: ffffa81540c23c00 x22: 0000000000000004
> x21: 0000000000000002 x20: 0000000000001a00
> x19: 0000000000000100 x18: 0000000000000010
> x17: 000000000001f000 x16: 000000000000007f
> x15: ffffa81540c24070 x14: ffffffffffffffff
> x13: ffffa815c0c137d7 x12: ffffa81540c137e4
> x11: ffffa81540c3e000 x10: ffffa81540ecee68
> x9 : ffffa8153f0f61d8 x8 : ffffa81540ecf000
> x7 : 0000000000000141 x6 : ffffa81540ecf401
> x5 : 0000000000000000 x4 : 0000000000000000
> x3 : 0000000000000000 x2 : 0000000000000000
> x1 : 0000000000000081 x0 : 0000000000001a00

Some of this is not really relevant to the commit log.  The ITS info,
page fault, some of the backtrace might help people google for this,
but I think the register dump is overkill.

> Call trace:
>  __alloc_pages_nodemask+0xe8/0x338
>  alloc_pages_node.constprop.0+0x34/0x40
>  its_probe_one+0x2f8/0xb18
>  gic_acpi_parse_madt_its+0x108/0x150
>  acpi_table_parse_entries_array+0x17c/0x264
>  acpi_table_parse_entries+0x48/0x6c
>  acpi_table_parse_madt+0x30/0x3c
>  its_init+0x1c4/0x644
>  gic_init_bases+0x4b8/0x4ec
>  gic_acpi_init+0x134/0x264
>  acpi_match_madt+0x4c/0x84
>  acpi_table_parse_entries_array+0x17c/0x264
>  acpi_table_parse_entries+0x48/0x6c
>  acpi_table_parse_madt+0x30/0x3c
>  __acpi_probe_device_table+0x8c/0xe8
>  irqchip_init+0x3c/0x48
>  init_IRQ+0xcc/0x100
>  start_kernel+0x33c/0x548
> 
> As we die in this case in existing kernels, we can be fairly sure that no one
> actually has such a firmware in production.  As such this patch avoids the
> complexity that would be needed to handle this corner case, and simply does
> not allow the ITS entry parsing code to instantiate new Numa Nodes.  If one
> is encountered that does not already exist, then NO_NUMA_NODE is assigned
> and a warning printed just as if the value had been greater than allowed
> Numa Nodes.

Are you saying we won't create a NUMA node based on an SRAT ITS entry?
Is there something about that in the spec?

> "SRAT: Invalid NUMA node -1 in ITS affinity"
> 
> I have only tested this for now on our ARM64 Kunpeng920 servers and
> a range of qemu x86 and arm64 configurations.
> 
> Note minor merge issue with Dan William's series [3].  Merge fixes should be
> straight forward.

It's a little hard to figure out what's going on here.  It might help
if you made a preliminary patch that added your new parameter but
preserved all existing behavior, then follow up with a second patch
that makes the real change you need.

> [1] Note in ACPI Specification 6.3 5.2.16 System Resource Affinity Table (SRAT)
> [2] https://patchwork.kernel.org/patch/10597777/
> [3] https://lore.kernel.org/patchwork/cover/1271398/
> 
> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
> ---
> 
> Possible open questions:
> * should we warn about a broken firmware trying to assign any device
>   to a non existent Proximity Domain?
> * previously an smmuv3 in IORT with a Proximity Domain set to a non existent
>   value would have resulted in a failure to add the device. After this change
>   it will be added to the default node.  Is that a problem?
> * for the smmuv3 we print that we have successfully mapped to a node even if
>   we have not.  Would making this clear be useful?
>   Perhaps this is a topic for a separate patch.
> 
>  Changes since RFC
>  * Fixed missing parameter in dmar.c
>  * Tested on some Qemu x86 models so confident enough to drop the RFC.
> 
>  arch/arm64/kernel/acpi_numa.c    | 2 +-
>  arch/ia64/kernel/acpi.c          | 2 +-
>  arch/x86/mm/srat.c               | 4 ++--
>  drivers/acpi/arm64/iort.c        | 2 +-
>  drivers/acpi/nfit/core.c         | 2 +-
>  drivers/acpi/numa/hmat.c         | 2 +-
>  drivers/acpi/numa/srat.c         | 8 ++++----
>  drivers/iommu/intel/dmar.c       | 2 +-
>  drivers/irqchip/irq-gic-v3-its.c | 7 ++++++-
>  include/acpi/acpi_numa.h         | 2 +-
>  include/linux/acpi.h             | 6 +++---
>  11 files changed, 22 insertions(+), 17 deletions(-)
> 
> diff --git a/arch/arm64/kernel/acpi_numa.c b/arch/arm64/kernel/acpi_numa.c
> index 7ff800045434..6ed47b058d76 100644
> --- a/arch/arm64/kernel/acpi_numa.c
> +++ b/arch/arm64/kernel/acpi_numa.c
> @@ -107,7 +107,7 @@ void __init acpi_numa_gicc_affinity_init(struct acpi_srat_gicc_affinity *pa)
>  		return;
>  
>  	pxm = pa->proximity_domain;
> -	node = acpi_map_pxm_to_node(pxm);
> +	node = acpi_map_pxm_to_node(pxm, true);
>  
>  	if (node == NUMA_NO_NODE || node >= MAX_NUMNODES) {
>  		pr_err("SRAT: Too many proximity domains %d\n", pxm);
> diff --git a/arch/ia64/kernel/acpi.c b/arch/ia64/kernel/acpi.c
> index a5636524af76..760a468864b7 100644
> --- a/arch/ia64/kernel/acpi.c
> +++ b/arch/ia64/kernel/acpi.c
> @@ -456,7 +456,7 @@ void __init acpi_numa_fixup(void)
>  	nodes_clear(node_online_map);
>  	for (i = 0; i < MAX_PXM_DOMAINS; i++) {
>  		if (pxm_bit_test(i)) {
> -			int nid = acpi_map_pxm_to_node(i);
> +			int nid = acpi_map_pxm_to_node(i, true);
>  			node_set_online(nid);
>  		}
>  	}
> diff --git a/arch/x86/mm/srat.c b/arch/x86/mm/srat.c
> index dac07e4f5834..6497d7c241ec 100644
> --- a/arch/x86/mm/srat.c
> +++ b/arch/x86/mm/srat.c
> @@ -45,7 +45,7 @@ acpi_numa_x2apic_affinity_init(struct acpi_srat_x2apic_cpu_affinity *pa)
>  			 pxm, apic_id);
>  		return;
>  	}
> -	node = acpi_map_pxm_to_node(pxm);
> +	node = acpi_map_pxm_to_node(pxm, true);
>  	if (node < 0) {
>  		printk(KERN_ERR "SRAT: Too many proximity domains %x\n", pxm);
>  		bad_srat();
> @@ -80,7 +80,7 @@ acpi_numa_processor_affinity_init(struct acpi_srat_cpu_affinity *pa)
>  	pxm = pa->proximity_domain_lo;
>  	if (acpi_srat_revision >= 2)
>  		pxm |= *((unsigned int*)pa->proximity_domain_hi) << 8;
> -	node = acpi_map_pxm_to_node(pxm);
> +	node = acpi_map_pxm_to_node(pxm, true);
>  	if (node < 0) {
>  		printk(KERN_ERR "SRAT: Too many proximity domains %x\n", pxm);
>  		bad_srat();
> diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
> index 28a6b387e80e..8133e7e6f9e3 100644
> --- a/drivers/acpi/arm64/iort.c
> +++ b/drivers/acpi/arm64/iort.c
> @@ -1293,7 +1293,7 @@ static int  __init arm_smmu_v3_set_proximity(struct device *dev,
>  
>  	smmu = (struct acpi_iort_smmu_v3 *)node->node_data;
>  	if (smmu->flags & ACPI_IORT_SMMU_V3_PXM_VALID) {
> -		int dev_node = acpi_map_pxm_to_node(smmu->pxm);
> +		int dev_node = acpi_map_pxm_to_node(smmu->pxm, false);
>  
>  		if (dev_node != NUMA_NO_NODE && !node_online(dev_node))
>  			return -EINVAL;
> diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c
> index 7c138a4edc03..6cb44bbaa71f 100644
> --- a/drivers/acpi/nfit/core.c
> +++ b/drivers/acpi/nfit/core.c
> @@ -2948,7 +2948,7 @@ static int acpi_nfit_register_region(struct acpi_nfit_desc *acpi_desc,
>  		ndr_desc->numa_node = acpi_map_pxm_to_online_node(
>  						spa->proximity_domain);
>  		ndr_desc->target_node = acpi_map_pxm_to_node(
> -				spa->proximity_domain);
> +				spa->proximity_domain, false);
>  	} else {
>  		ndr_desc->numa_node = NUMA_NO_NODE;
>  		ndr_desc->target_node = NUMA_NO_NODE;
> diff --git a/drivers/acpi/numa/hmat.c b/drivers/acpi/numa/hmat.c
> index 2c32cfb72370..3c0414816772 100644
> --- a/drivers/acpi/numa/hmat.c
> +++ b/drivers/acpi/numa/hmat.c
> @@ -666,7 +666,7 @@ static void hmat_register_target_device(struct memory_target *target,
>  
>  	pdev->dev.numa_node = acpi_map_pxm_to_online_node(target->memory_pxm);
>  	info = (struct memregion_info) {
> -		.target_node = acpi_map_pxm_to_node(target->memory_pxm),
> +		.target_node = acpi_map_pxm_to_node(target->memory_pxm, false),
>  	};
>  	rc = platform_device_add_data(pdev, &info, sizeof(info));
>  	if (rc < 0) {
> diff --git a/drivers/acpi/numa/srat.c b/drivers/acpi/numa/srat.c
> index 5be5a977da1b..ed7d31795f4d 100644
> --- a/drivers/acpi/numa/srat.c
> +++ b/drivers/acpi/numa/srat.c
> @@ -52,7 +52,7 @@ static void __acpi_map_pxm_to_node(int pxm, int node)
>  		node_to_pxm_map[node] = pxm;
>  }
>  
> -int acpi_map_pxm_to_node(int pxm)
> +int acpi_map_pxm_to_node(int pxm, bool create)
>  {
>  	int node;
>  
> @@ -62,7 +62,7 @@ int acpi_map_pxm_to_node(int pxm)
>  	node = pxm_to_node_map[pxm];
>  
>  	if (node == NUMA_NO_NODE) {
> -		if (nodes_weight(nodes_found_map) >= MAX_NUMNODES)
> +		if (nodes_weight(nodes_found_map) >= MAX_NUMNODES || !create)
>  			return NUMA_NO_NODE;
>  		node = first_unset_node(nodes_found_map);
>  		__acpi_map_pxm_to_node(pxm, node);
> @@ -229,7 +229,7 @@ acpi_numa_memory_affinity_init(struct acpi_srat_mem_affinity *ma)
>  	if (acpi_srat_revision <= 1)
>  		pxm &= 0xff;
>  
> -	node = acpi_map_pxm_to_node(pxm);
> +	node = acpi_map_pxm_to_node(pxm, true);
>  	if (node == NUMA_NO_NODE || node >= MAX_NUMNODES) {
>  		pr_err("SRAT: Too many proximity domains.\n");
>  		goto out_err_bad_srat;
> @@ -444,6 +444,6 @@ int acpi_get_node(acpi_handle handle)
>  
>  	pxm = acpi_get_pxm(handle);
>  
> -	return acpi_map_pxm_to_node(pxm);
> +	return acpi_map_pxm_to_node(pxm, false);
>  }
>  EXPORT_SYMBOL(acpi_get_node);
> diff --git a/drivers/iommu/intel/dmar.c b/drivers/iommu/intel/dmar.c
> index 683b812c5c47..fec90800381e 100644
> --- a/drivers/iommu/intel/dmar.c
> +++ b/drivers/iommu/intel/dmar.c
> @@ -473,7 +473,7 @@ static int dmar_parse_one_rhsa(struct acpi_dmar_header *header, void *arg)
>  	rhsa = (struct acpi_dmar_rhsa *)header;
>  	for_each_drhd_unit(drhd) {
>  		if (drhd->reg_base_addr == rhsa->base_address) {
> -			int node = acpi_map_pxm_to_node(rhsa->proximity_domain);
> +			int node = acpi_map_pxm_to_node(rhsa->proximity_domain, false);
>  
>  			if (!node_online(node))
>  				node = NUMA_NO_NODE;
> diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
> index 6a5a87fc4601..44cb53fa6afe 100644
> --- a/drivers/irqchip/irq-gic-v3-its.c
> +++ b/drivers/irqchip/irq-gic-v3-its.c
> @@ -5248,7 +5248,12 @@ static int __init gic_acpi_parse_srat_its(union acpi_subtable_headers *header,
>  		return -EINVAL;
>  	}
>  
> -	node = acpi_map_pxm_to_node(its_affinity->proximity_domain);
> +	/*
> +	 * Note that in theory a new proximity node could be created by this
> +	 * entry as it is an SRAT resource allocation structure.
> +	 * We do not currently support doing so.
> +	 */
> +	node = acpi_map_pxm_to_node(its_affinity->proximity_domain, false);
>  
>  	if (node == NUMA_NO_NODE || node >= MAX_NUMNODES) {
>  		pr_err("SRAT: Invalid NUMA node %d in ITS affinity\n", node);
> diff --git a/include/acpi/acpi_numa.h b/include/acpi/acpi_numa.h
> index fdebcfc6c8df..6935c7516262 100644
> --- a/include/acpi/acpi_numa.h
> +++ b/include/acpi/acpi_numa.h
> @@ -15,7 +15,7 @@
>  
>  extern int pxm_to_node(int);
>  extern int node_to_pxm(int);
> -extern int acpi_map_pxm_to_node(int);
> +extern int acpi_map_pxm_to_node(int, bool);
>  extern unsigned char acpi_srat_revision;
>  extern int acpi_numa __initdata;
>  
> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
> index d661cd0ee64d..1414b7e0a486 100644
> --- a/include/linux/acpi.h
> +++ b/include/linux/acpi.h
> @@ -416,7 +416,7 @@ extern void acpi_osi_setup(char *str);
>  extern bool acpi_osi_is_win8(void);
>  
>  #ifdef CONFIG_ACPI_NUMA
> -int acpi_map_pxm_to_node(int pxm);
> +int acpi_map_pxm_to_node(int pxm, bool create);
>  int acpi_get_node(acpi_handle handle);
>  
>  /**
> @@ -436,7 +436,7 @@ int acpi_get_node(acpi_handle handle);
>   */
>  static inline int acpi_map_pxm_to_online_node(int pxm)
>  {
> -	int node = acpi_map_pxm_to_node(pxm);
> +	int node = acpi_map_pxm_to_node(pxm, false);
>  
>  	return numa_map_to_online_node(node);
>  }
> @@ -445,7 +445,7 @@ static inline int acpi_map_pxm_to_online_node(int pxm)
>  {
>  	return 0;
>  }
> -static inline int acpi_map_pxm_to_node(int pxm)
> +static inline int acpi_map_pxm_to_node(int pxm, bool create)
>  {
>  	return 0;
>  }
> -- 
> 2.19.1
> 

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