Previously the e820_table_kexec was exported to sysfs since kexec-tools uses
the memmap entries to prepare the e820 table for the new kernel.
Commit[1] introduced e820_table_firmware and changed the behavior to export
the firmware table instead. Originally kexec_file_load and kexec_load
both use e820_table_kexec. Since the sysfs exported entries are from
e820_table_firmware people now need to tune both tables for kexec.
Restore the old behavior so kexec_load and kexec_file_load work with only
one table update. The e820_table_firmware is used by hibernation kernel
code and it works without the sysfs exporting. Also remove the sev
e820_table_firmware updating code.
Also update the code comments here and drop the comments about setup_data
reservation since it is not needed any more after commit [2].
[1]: commit 12df216c61c8 ("x86/boot/e820: Introduce the bootloader provided e820_table_firmware[] table")
[2]: commit fc7f27cda843 ("x86/kexec: Do not update E820 kexec table for setup_data")
Signed-off-by: Dave Young <dyoung@xxxxxxxxxx>
---
arch/x86/kernel/e820.c | 20 ++++++++++----------
arch/x86/virt/svm/sev.c | 1 -
2 files changed, 10 insertions(+), 11 deletions(-)
Index: linux/arch/x86/kernel/e820.c
===================================================================
--- linux.orig/arch/x86/kernel/e820.c 2025-01-28 11:27:02.372171910 +0800
+++ linux/arch/x86/kernel/e820.c 2025-01-28 20:36:00.031075385 +0800
@@ -28,18 +28,13 @@
* the first 128 E820 memory entries in boot_params.e820_table and the remaining
* (if any) entries of the SETUP_E820_EXT nodes. We use this to:
*
- * - inform the user about the firmware's notion of memory layout
- * via /sys/firmware/memmap
- *
* - the hibernation code uses it to generate a kernel-independent CRC32
* checksum of the physical memory layout of a system.
*
* - 'e820_table_kexec': a slightly modified (by the kernel) firmware version
* passed to us by the bootloader - the major difference between
- * e820_table_firmware[] and this one is that, the latter marks the setup_data
- * list created by the EFI boot stub as reserved, so that kexec can reuse the
- * setup_data information in the second kernel. Besides, e820_table_kexec[]
- * might also be modified by the kexec itself to fake a mptable.
+ * e820_table_firmware[] and this one is that e820_table_kexec[]
+ * might be modified by the kexec itself to fake a mptable.
* We use this to:
*
* - kexec, which is a bootloader in disguise, uses the original E820
@@ -47,6 +42,11 @@
* can have a restricted E820 map while the kexec()-ed kexec-kernel
* can have access to full memory - etc.
*
+ * Export the memory layout via /sys/firmware/memmap. kexec-tools uses
+ * the entries to create an E820 table for kexec kernel.
+ *
+ * kexec_file_load in-kernel code uses the table for kexec kernel.
+ *
* - 'e820_table': this is the main E820 table that is massaged by the
* low level x86 platform code, or modified by boot parameters, before
* passed on to higher level MM layers.
@@ -1176,9 +1176,9 @@
res++;
}
- /* Expose the bootloader-provided memory layout to the sysfs. */
- for (i = 0; i < e820_table_firmware->nr_entries; i++) {
- struct e820_entry *entry = e820_table_firmware->entries + i;
+ /* Expose the kexec e820 table to the sysfs. */
+ for (i = 0; i < e820_table_kexec->nr_entries; i++) {
+ struct e820_entry *entry = e820_table_kexec->entries + i;
firmware_map_add_early(entry->addr, entry->addr + entry->size, e820_type_to_string(entry));
}
Index: linux/arch/x86/virt/svm/sev.c
===================================================================
--- linux.orig/arch/x86/virt/svm/sev.c 2025-01-28 20:21:32.253078107 +0800
+++ linux/arch/x86/virt/svm/sev.c 2025-01-28 20:23:19.653201528 +0800
@@ -198,7 +198,6 @@
pr_info("Reserving start/end of RMP table on a 2MB boundary [0x%016llx]\n", pa);
e820__range_update(pa, PMD_SIZE, E820_TYPE_RAM, E820_TYPE_RESERVED);
e820__range_update_table(e820_table_kexec, pa, PMD_SIZE, E820_TYPE_RAM, E820_TYPE_RESERVED);
- e820__range_update_table(e820_table_firmware, pa, PMD_SIZE, E820_TYPE_RAM, E820_TYPE_RESERVED);
if (!memblock_is_region_reserved(pa, PMD_SIZE))
memblock_reserve(pa, PMD_SIZE);
}
