[RFC PATCH v2 6/7] pmpool: Restore state from device tree post-kexec
Stanislav Kinsburskii
skinsburskii at linux.microsoft.com
Mon Sep 25 14:28:22 PDT 2023
From: Stanislav Kinsburskii <stanislav.kinsburskii at gmail.com>
Retrieve the pmpool bitmap from metadata in the fdt passed over kexec,
bypassing the need for reinitialization. This ensures the seamless transfer
of the pmpool state across kexec.
Signed-off-by: Stanislav Kinsburskii <skinsburskii at linux.microsoft.com>
---
mm/pmpool.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 46 insertions(+)
diff --git a/mm/pmpool.c b/mm/pmpool.c
index f2173db782d6..6c1a28fd3493 100644
--- a/mm/pmpool.c
+++ b/mm/pmpool.c
@@ -9,6 +9,7 @@
#include <linux/libfdt.h>
#include <linux/memblock.h>
#include <linux/mm.h>
+#include <linux/of.h>
#include <linux/pmpool.h>
#include "cma.h"
@@ -49,11 +50,56 @@ static void pmpool_fixup_cma(struct cma *cma)
pr_info("CMA bitmap moved to %#llx\n", virt_to_phys(cma->bitmap));
}
+static int pmpool_fdt_restore(struct cma *cma)
+{
+ struct device_node *dn;
+ u64 val;
+
+ dn = of_find_compatible_node(NULL, NULL, "pmpool");
+ if (!dn)
+ return -ENOENT;
+
+ if (of_property_read_u64(dn, "base", &val)) {
+ pr_err("invalid fdt: no base\n");
+ return -EINVAL;
+ }
+ if (val != PFN_PHYS(cma->base_pfn)) {
+ pr_err("fdt base doesn't match: %#llx != %#llx\n",
+ val, PFN_PHYS(cma->base_pfn));
+ return -EINVAL;
+ }
+
+ if (of_property_read_u64(dn, "size", &val)) {
+ pr_err("invalid fdt: no size\n");
+ return -EINVAL;
+ }
+ if (val != (cma->count << PAGE_SHIFT)) {
+ pr_err("fdt size doesn't match: %#llx != %#lx\n",
+ val, cma->count << PAGE_SHIFT);
+ return -EINVAL;
+ }
+
+ if (of_property_read_u64(dn, "bitmap", &val)) {
+ pr_err("invalid fdt: no bitmap\n");
+ return -EINVAL;
+ }
+
+ pr_info("CMA bitmap restored to %#llx\n", val);
+
+ bitmap_free(cma->bitmap);
+ cma->bitmap = phys_to_virt(val);
+
+ return 0;
+}
+
static int __init default_pmpool_fixup_cma(void)
{
if (!default_pmpool)
return 0;
+ if (!pmpool_fdt_restore(default_pmpool->cma))
+ return 0;
+
pmpool_fixup_cma(default_pmpool->cma);
return 0;
}
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