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Subject[RFC PATCH] ACPI: Only create numa nodes from entries in SRAT or SRAT emulation.
Date
Here, I will use the term Proximity Domains for the ACPI description and
Numa Nodes for the in kernel representation.

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

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).

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.

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.

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...

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:

ITS [mem 0x202100000-0x20211ffff]
ITS@0x0000000202100000: 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
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.

"SRAT: Invalid NUMA node -1 in ITS affinity"

I have only tested this for now on our ARM64 Kunpeng920 servers.

Open questions:
* should we warn about a broken firmware or insufficent value of
NUMA_NODES_SHIFT if we find a 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?

[1] Note in ACPI Specification 6.3 5.2.16 System Resource Affinity Table (SRAT)
[2] https://patchwork.kernel.org/patch/10597777/

Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
---
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/irqchip/irq-gic-v3-its.c | 6 +++++-
include/acpi/acpi_numa.h | 2 +-
include/linux/acpi.h | 6 +++---
10 files changed, 20 insertions(+), 16 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/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index cd685f521c77..0b11876d0799 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -5248,7 +5248,11 @@ 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
+ */
+ 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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