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kho: remove global preserved_mem_map and store state in FDT

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Currently, the serialized memory map is tracked via
kho_out.preserved_mem_map and copied to the FDT during finalization.  This
double tracking is redundant.

Remove preserved_mem_map from kho_out.  Instead, maintain the physical
address of the head chunk directly in the preserved-memory-map FDT
property.

Introduce kho_update_memory_map() to manage this property. This function
handles:
1. Retrieving and freeing any existing serialized map (handling the
   abort/retry case).
2. Updating the FDT property with the new chunk address.

This establishes the FDT as the single source of truth for the handover
state.

Link: https://lkml.kernel.org/r/20251114190002.3311679-9-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Cc: Alexander Graf <graf@amazon.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Baoquan He <bhe@redhat.com>
Cc: Coiby Xu <coxu@redhat.com>
Cc: Dave Vasilevsky <dave@vasilevsky.ca>
Cc: Eric Biggers <ebiggers@google.com>
Cc: Kees Cook <kees@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Pasha Tatashin
2025-11-14 13:59:57 -05:00
committed by Andrew Morton
parent 71960fe134
commit efa3a9775a
1 changed files with 26 additions and 17 deletions
Download Patch File Download Diff File Expand all files Collapse all files

43
kernel/liveupdate/kexec_handover.c
View File

@@ -119,9 +119,6 @@ struct kho_out {
struct mutex fdts_lock;
struct kho_mem_track track;
/* First chunk of serialized preserved memory map */
struct khoser_mem_chunk *preserved_mem_map;
struct kho_debugfs dbg;
};
@@ -382,6 +379,27 @@ static void kho_mem_ser_free(struct khoser_mem_chunk *first_chunk)
}
}
/*
* Update memory map property, if old one is found discard it via
* kho_mem_ser_free().
*/
static void kho_update_memory_map(struct khoser_mem_chunk *first_chunk)
{
void *ptr;
u64 phys;
ptr = fdt_getprop_w(kho_out.fdt, 0, PROP_PRESERVED_MEMORY_MAP, NULL);
/* Check and discard previous memory map */
phys = get_unaligned((u64 *)ptr);
if (phys)
kho_mem_ser_free((struct khoser_mem_chunk *)phys_to_virt(phys));
/* Update with the new value */
phys = first_chunk ? (u64)virt_to_phys(first_chunk) : 0;
put_unaligned(phys, (u64 *)ptr);
}
static int kho_mem_serialize(struct kho_out *kho_out)
{
struct khoser_mem_chunk *first_chunk = NULL;
@@ -422,7 +440,7 @@ static int kho_mem_serialize(struct kho_out *kho_out)
}
}
kho_out->preserved_mem_map = first_chunk;
kho_update_memory_map(first_chunk);
return 0;
@@ -1223,8 +1241,7 @@ int kho_abort(void)
if (!kho_out.finalized)
return -ENOENT;
kho_mem_ser_free(kho_out.preserved_mem_map);
kho_out.preserved_mem_map = NULL;
kho_update_memory_map(NULL);
kho_out.finalized = false;
return 0;
@@ -1234,21 +1251,15 @@ static int __kho_finalize(void)
{
void *root = kho_out.fdt;
struct kho_sub_fdt *fdt;
u64 *preserved_mem_map;
u64 empty_mem_map = 0;
int err;
err = fdt_create(root, PAGE_SIZE);
err |= fdt_finish_reservemap(root);
err |= fdt_begin_node(root, "");
err |= fdt_property_string(root, "compatible", KHO_FDT_COMPATIBLE);
/**
* Reserve the preserved-memory-map property in the root FDT, so
* that all property definitions will precede subnodes created by
* KHO callers.
*/
err |= fdt_property_placeholder(root, PROP_PRESERVED_MEMORY_MAP,
sizeof(*preserved_mem_map),
(void **)&preserved_mem_map);
err |= fdt_property(root, PROP_PRESERVED_MEMORY_MAP, &empty_mem_map,
sizeof(empty_mem_map));
if (err)
goto err_exit;
@@ -1271,8 +1282,6 @@ static int __kho_finalize(void)
if (err)
goto err_exit;
*preserved_mem_map = (u64)virt_to_phys(kho_out.preserved_mem_map);
return 0;
err_exit: