David Gibson [off-list ref] writes:

On Mon, Jun 28, 2021 at 08:41:15PM +0530, Aneesh Kumar K.V wrote:

quoted

The associativity details of the newly added resourced are collected from
the hypervisor via "ibm,configure-connector" rtas call. Update the numa
distance details of the newly added numa node after the above call.

Instead of updating NUMA distance every time we lookup a node id
from the associativity property, add helpers that can be used
during boot which does this only once. Also remove the distance
update from node id lookup helpers.

Signed-off-by: Aneesh Kumar K.V <redacted>
---
 arch/powerpc/mm/numa.c                        | 173 +++++++++++++-----
 arch/powerpc/platforms/pseries/hotplug-cpu.c  |   2 +
 .../platforms/pseries/hotplug-memory.c        |   2 +
 arch/powerpc/platforms/pseries/pseries.h      |   1 +
 4 files changed, 132 insertions(+), 46 deletions(-)

diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
index 0ec16999beef..7b142f79d600 100644
--- a/arch/powerpc/mm/numa.c
+++ b/arch/powerpc/mm/numa.c

@@ -208,22 +208,6 @@ int __node_distance(int a, int b)
 }
 EXPORT_SYMBOL(__node_distance);
 
-static void initialize_distance_lookup_table(int nid,
-		const __be32 *associativity)
-{
-	int i;
-
-	if (affinity_form != FORM1_AFFINITY)
-		return;
-
-	for (i = 0; i < max_associativity_domain_index; i++) {
-		const __be32 *entry;
-
-		entry = &associativity[be32_to_cpu(distance_ref_points[i]) - 1];
-		distance_lookup_table[nid][i] = of_read_number(entry, 1);
-	}
-}
-
 /*
  * Returns nid in the range [0..nr_node_ids], or -1 if no useful NUMA
  * info is found.

@@ -241,15 +225,6 @@ static int associativity_to_nid(const __be32 *associativity)
 	/* POWER4 LPAR uses 0xffff as invalid node */
 	if (nid == 0xffff || nid >= nr_node_ids)
 		nid = NUMA_NO_NODE;
-
-	if (nid > 0 &&
-		of_read_number(associativity, 1) >= max_associativity_domain_index) {
-		/*
-		 * Skip the length field and send start of associativity array
-		 */
-		initialize_distance_lookup_table(nid, associativity + 1);
-	}
-
 out:
 	return nid;
 }

@@ -287,6 +262,49 @@ int of_node_to_nid(struct device_node *device)
 }
 EXPORT_SYMBOL(of_node_to_nid);
 
+static void __initialize_form1_numa_distance(const __be32 *associativity)
+{
+	int i, nid;
+
+	if (affinity_form != FORM1_AFFINITY)

Since this shouldn't be called on a !form1 system, this could be a WARN_ON().

The way we call functions currently, instead of doing

if (affinity_form == FORM1_AFFINITY)
    __initialize_form1_numa_distance()

We avoid doing the if check in multiple places. For example
parse_numa_properties will fetch the associativity array to find the
details of online node and set it online. We use the same code path to
initialize distance.

		if (__vphn_get_associativity(i, vphn_assoc) == 0) {
			nid = associativity_to_nid(vphn_assoc);
			__initialize_form1_numa_distance(vphn_assoc);
		} else {

			cpu = of_get_cpu_node(i, NULL);
			BUG_ON(!cpu);

			associativity = of_get_associativity(cpu);
			if (associativity) {
				nid = associativity_to_nid(associativity);
				__initialize_form1_numa_distance(associativity);
			}

We avoid the the if (affinity_form == FORM1_AFFINITY) check there by
moving the check inside __initialize_form1_numa_distance().

quoted

+		return;
+
+	if (of_read_number(associativity, 1) >= primary_domain_index) {
+		nid = of_read_number(&associativity[primary_domain_index], 1);

This computes the nid from the assoc array independently of
associativity_to_nid, which doesn't seem like a good idea.  Wouldn't
it be better to call assocaitivity_to_nid(), then make the next bit
conditional on nid !== NUMA_NO_NODE?

@@ -302,9 +302,8 @@ static void __initialize_form1_numa_distance(const __be32 *associativity)
 	if (affinity_form != FORM1_AFFINITY)
 		return;
 
-	if (of_read_number(associativity, 1) >= primary_domain_index) {
-		nid = of_read_number(&associativity[primary_domain_index], 1);
-
+	nid = associativity_to_nid(associativity);
+	if (nid != NUMA_NO_NODE) {
 		for (i = 0; i < distance_ref_points_depth; i++) {
 			const __be32 *entry;
 

quoted

+
+		for (i = 0; i < max_associativity_domain_index; i++) {
+			const __be32 *entry;
+
+			entry = &associativity[be32_to_cpu(distance_ref_points[i])];
+			distance_lookup_table[nid][i] = of_read_number(entry, 1);
+		}
+	}
+}
+
+static void initialize_form1_numa_distance(struct device_node *node)
+{
+	const __be32 *associativity;
+
+	associativity = of_get_associativity(node);
+	if (!associativity)
+		return;
+
+	__initialize_form1_numa_distance(associativity);
+}
+
+/*
+ * Used to update distance information w.r.t newly added node.
+ */
+void update_numa_distance(struct device_node *node)
+{
+	if (affinity_form == FORM0_AFFINITY)
+		return;
+	else if (affinity_form == FORM1_AFFINITY) {
+		initialize_form1_numa_distance(node);
+		return;
+	}
+}
+
 static int __init find_primary_domain_index(void)
 {
 	int index;

@@ -433,6 +451,48 @@ static int of_get_assoc_arrays(struct assoc_arrays *aa)
 	return 0;
 }
 
+static int get_nid_and_numa_distance(struct drmem_lmb *lmb)
+{
+	struct assoc_arrays aa = { .arrays = NULL };
+	int default_nid = NUMA_NO_NODE;
+	int nid = default_nid;
+	int rc, index;
+
+	if ((primary_domain_index < 0) || !numa_enabled)

Under what circumstances could you get primary_domain_index < 0?

IIUC that is to handle failure to parse device tree.
ea9f5b702fe0215188fba2eda117419e4ae90a67

quoted

+		return default_nid;
+
+	rc = of_get_assoc_arrays(&aa);
+	if (rc)
+		return default_nid;
+
+	if (primary_domain_index <= aa.array_sz &&
+	    !(lmb->flags & DRCONF_MEM_AI_INVALID) && lmb->aa_index < aa.n_arrays) {
+		index = lmb->aa_index * aa.array_sz + primary_domain_index - 1;

Does anywhere verify that primary_domain_index <= aa.array_sz?

That is the first part of the check?

quoted

+		nid = of_read_number(&aa.arrays[index], 1);
+
+		if (nid == 0xffff || nid >= nr_node_ids)
+			nid = default_nid;
+		if (nid > 0 && affinity_form == FORM1_AFFINITY) {
+			int i;
+			const __be32 *associativity;
+
+			index = lmb->aa_index * aa.array_sz;
+			associativity = &aa.arrays[index];
+			/*
+			 * lookup array associativity entries have different format
+			 * There is no length of the array as the first element.

The difference it very small, and this is not a hot path.  Couldn't
you reduce a chunk of code by prepending aa.array_sz, then re-using
__initialize_form1_numa_distance.  Or even making
__initialize_form1_numa_distance() take the length as a parameter.

The changes are small but confusing w.r.t how we look at the
associativity-lookup-arrays. The way we interpret associativity array
and associativity lookup array using primary_domain_index is different.
Hence the '-1' in the node lookup here. 

	index = lmb->aa_index * aa.array_sz + primary_domain_index - 1;
	nid = of_read_number(&aa.arrays[index], 1);

quoted

+			 */
+			for (i = 0; i < max_associativity_domain_index; i++) {
+				const __be32 *entry;
+
+				entry = &associativity[be32_to_cpu(distance_ref_points[i]) - 1];

Does anywhere verify that distance_ref_points[i] <= aa.array_size for
every i?

We do check for 

	if (primary_domain_index <= aa.array_sz &&

quoted

+				distance_lookup_table[nid][i] = of_read_number(entry, 1);
+			}
+		}
+	}
+	return nid;
+}
+
 /*
  * This is like of_node_to_nid_single() for memory represented in the
  * ibm,dynamic-reconfiguration-memory node.

@@ -458,21 +518,14 @@ int of_drconf_to_nid_single(struct drmem_lmb *lmb)
 
 		if (nid == 0xffff || nid >= nr_node_ids)
 			nid = default_nid;
-
-		if (nid > 0) {
-			index = lmb->aa_index * aa.array_sz;
-			initialize_distance_lookup_table(nid,
-							&aa.arrays[index]);
-		}
 	}
-
 	return nid;
 }
 
 #ifdef CONFIG_PPC_SPLPAR
-static int vphn_get_nid(long lcpu)
+
+static int __vphn_get_associativity(long lcpu, __be32 *associativity)
 {
-	__be32 associativity[VPHN_ASSOC_BUFSIZE] = {0};
 	long rc, hwid;
 
 	/*

@@ -492,10 +545,22 @@ static int vphn_get_nid(long lcpu)
 
 		rc = hcall_vphn(hwid, VPHN_FLAG_VCPU, associativity);
 		if (rc == H_SUCCESS)
-			return associativity_to_nid(associativity);
+			return 0;
 	}
 
+	return -1;
+}
+
+static int vphn_get_nid(long lcpu)
+{
+	__be32 associativity[VPHN_ASSOC_BUFSIZE] = {0};
+
+
+	if (!__vphn_get_associativity(lcpu, associativity))
+		return associativity_to_nid(associativity);
+
 	return NUMA_NO_NODE;
+
 }
 #else
 static int vphn_get_nid(long unused)

@@ -692,7 +757,7 @@ static int __init numa_setup_drmem_lmb(struct drmem_lmb *lmb,
 			size = read_n_cells(n_mem_size_cells, usm);
 		}
 
-		nid = of_drconf_to_nid_single(lmb);
+		nid = get_nid_and_numa_distance(lmb);
 		fake_numa_create_new_node(((base + size) >> PAGE_SHIFT),
 					  &nid);
 		node_set_online(nid);

@@ -709,6 +774,7 @@ static int __init parse_numa_properties(void)
 	struct device_node *memory;
 	int default_nid = 0;
 	unsigned long i;
+	const __be32 *associativity;
 
 	if (numa_enabled == 0) {
 		printk(KERN_WARNING "NUMA disabled by user\n");

@@ -734,18 +800,30 @@ static int __init parse_numa_properties(void)
 	 * each node to be onlined must have NODE_DATA etc backing it.
 	 */
 	for_each_present_cpu(i) {
+		__be32 vphn_assoc[VPHN_ASSOC_BUFSIZE];
 		struct device_node *cpu;
-		int nid = vphn_get_nid(i);
+		int nid = NUMA_NO_NODE;
 
-		/*
-		 * Don't fall back to default_nid yet -- we will plug
-		 * cpus into nodes once the memory scan has discovered
-		 * the topology.
-		 */
-		if (nid == NUMA_NO_NODE) {
+		memset(vphn_assoc, 0, VPHN_ASSOC_BUFSIZE * sizeof(__be32));

What's the memset() for?  AFAICT you only look at vphn_assoc in the
branch where __vphn_get_associativity() succeeds.

That was done to match the existing code. We do use a zero filled array
when making that hcall in this code path. I don't see us doing that
everywhere. But didn't want to change that behaviour in this patch.

-static int vphn_get_nid(long lcpu)
+
+static int __vphn_get_associativity(long lcpu, __be32 *associativity)
 {
 -	__be32 associativity[VPHN_ASSOC_BUFSIZE] = {0};
  	long rc, hwid;

quoted

+
+		if (__vphn_get_associativity(i, vphn_assoc) == 0) {
+			nid = associativity_to_nid(vphn_assoc);
+			__initialize_form1_numa_distance(vphn_assoc);
+		} else {
+
+			/*
+			 * Don't fall back to default_nid yet -- we will plug
+			 * cpus into nodes once the memory scan has discovered
+			 * the topology.
+			 */
 			cpu = of_get_cpu_node(i, NULL);
 			BUG_ON(!cpu);
-			nid = of_node_to_nid_single(cpu);
+
+			associativity = of_get_associativity(cpu);
+			if (associativity) {
+				nid = associativity_to_nid(associativity);
+				__initialize_form1_numa_distance(associativity);
+			}
 			of_node_put(cpu);
 		}
 

@@ -781,8 +859,11 @@ static int __init parse_numa_properties(void)
 		 * have associativity properties.  If none, then
 		 * everything goes to default_nid.
 		 */
-		nid = of_node_to_nid_single(memory);
-		if (nid < 0)
+		associativity = of_get_associativity(memory);
+		if (associativity) {
+			nid = associativity_to_nid(associativity);
+			__initialize_form1_numa_distance(associativity);
+		} else
 			nid = default_nid;
 
 		fake_numa_create_new_node(((start + size) >> PAGE_SHIFT), &nid);

diff --git a/arch/powerpc/platforms/pseries/hotplug-cpu.c b/arch/powerpc/platforms/pseries/hotplug-cpu.c
index 7e970f81d8ff..778b6ab35f0d 100644
--- a/arch/powerpc/platforms/pseries/hotplug-cpu.c
+++ b/arch/powerpc/platforms/pseries/hotplug-cpu.c

@@ -498,6 +498,8 @@ static ssize_t dlpar_cpu_add(u32 drc_index)
 		return saved_rc;
 	}
 
+	update_numa_distance(dn);
+
 	rc = dlpar_online_cpu(dn);
 	if (rc) {
 		saved_rc = rc;

diff --git a/arch/powerpc/platforms/pseries/hotplug-memory.c b/arch/powerpc/platforms/pseries/hotplug-memory.c
index 36f66556a7c6..40d350f31a34 100644
--- a/arch/powerpc/platforms/pseries/hotplug-memory.c
+++ b/arch/powerpc/platforms/pseries/hotplug-memory.c

@@ -180,6 +180,8 @@ static int update_lmb_associativity_index(struct drmem_lmb *lmb)
 		return -ENODEV;
 	}
 
+	update_numa_distance(lmb_node);
+
 	dr_node = of_find_node_by_path("/ibm,dynamic-reconfiguration-memory");
 	if (!dr_node) {
 		dlpar_free_cc_nodes(lmb_node);

diff --git a/arch/powerpc/platforms/pseries/pseries.h b/arch/powerpc/platforms/pseries/pseries.h
index 1f051a786fb3..663a0859cf13 100644
--- a/arch/powerpc/platforms/pseries/pseries.h
+++ b/arch/powerpc/platforms/pseries/pseries.h

@@ -113,4 +113,5 @@ extern u32 pseries_security_flavor;
 void pseries_setup_security_mitigations(void);
 void pseries_lpar_read_hblkrm_characteristics(void);
 
+void update_numa_distance(struct device_node *node);
 #endif /* _PSERIES_PSERIES_H */

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson