From 92719518d6336db632a00bcfb2ec28a8f82998a8 Mon Sep 17 00:00:00 2001
From: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
Date: Mon, 29 Jul 2024 16:53:18 +0100
Subject: [PATCH] numa/emulation: Check emulated zones around the CMA window

... Make sure CMA zones do not straddle the emulated NUMA nodes ...

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
---
 include/linux/cma.h |  6 ++++++
 mm/cma.c            | 36 ++++++++++++++++++++++++++++++++++++
 mm/numa_emulation.c |  6 ++++++
 3 files changed, 48 insertions(+)

--- a/include/linux/cma.h
+++ b/include/linux/cma.h
@@ -56,6 +56,7 @@ extern void cma_reserve_pages_on_error(s
 #ifdef CONFIG_CMA
 struct folio *cma_alloc_folio(struct cma *cma, int order, gfp_t gfp);
 bool cma_free_folio(struct cma *cma, const struct folio *folio);
+int cma_check_range(u64 *start, u64 *end);
 #else
 static inline struct folio *cma_alloc_folio(struct cma *cma, int order, gfp_t gfp)
 {
@@ -66,6 +67,11 @@ static inline bool cma_free_folio(struct
 {
 	return false;
 }
+
+static inline int cma_check_range(u64 *start, u64 *end)
+{
+	return 0;
+}
 #endif
 
 #endif
--- a/mm/cma.c
+++ b/mm/cma.c
@@ -602,3 +602,39 @@ int cma_for_each_area(int (*it)(struct c
 
 	return 0;
 }
+
+struct cma_check_range_data {
+	u64 start, end;
+};
+
+static int check_range(struct cma *cma_, void *data)
+{
+	struct cma_check_range_data *range = data;
+	struct cma_check_range_data cma;
+	bool starts_in_range;
+	bool ends_in_range;
+
+	cma.start = cma_get_base(cma_);
+	cma.end = cma.start + cma_get_size(cma_) - 1;
+
+	starts_in_range = cma.start >= range->start && cma.start <= range->end;
+	ends_in_range = cma.end >= range->start && cma.end <= range->end;
+
+	if (starts_in_range == ends_in_range)
+		return 0;
+
+	pr_notice("CMA %s [%llx-%llx] straddles range [%llx-%llx]\n",
+		  cma_->name, cma.start, cma.end, range->start, range->end);
+
+	return -EINVAL;
+}
+
+int cma_check_range(u64 *start, u64 *end)
+{
+	struct cma_check_range_data range = {
+		.start = *start,
+		.end = *end,
+	};
+
+	return cma_for_each_area(check_range, &range);
+}
--- a/mm/numa_emulation.c
+++ b/mm/numa_emulation.c
@@ -7,6 +7,7 @@
 #include <linux/topology.h>
 #include <linux/memblock.h>
 #include <linux/numa_memblks.h>
+#include <linux/cma.h>
 #include <asm/numa.h>
 
 #define FAKE_NODE_MIN_SIZE	((u64)32 << 20)
@@ -51,6 +52,7 @@ static int __init emu_setup_memblk(struc
 {
 	struct numa_memblk *eb = &ei->blk[ei->nr_blks];
 	struct numa_memblk *pb = &pi->blk[phys_blk];
+	int ret;
 
 	if (ei->nr_blks >= NR_NODE_MEMBLKS) {
 		pr_err("NUMA: Too many emulated memblks, failing emulation\n");
@@ -62,6 +64,10 @@ static int __init emu_setup_memblk(struc
 	eb->end = pb->start + size;
 	eb->nid = nid;
 
+	ret = cma_check_range(&eb->start, &eb->end);
+	if (ret)
+		return ret;
+
 	if (emu_nid_to_phys[nid] == NUMA_NO_NODE)
 		emu_nid_to_phys[nid] = pb->nid;