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x86/kexec: Export e820_table_kexec[] to sysfs

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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.

The following commit, ~8 years ago, introduced e820_table_firmware[] and changed
the behavior to export the firmware table instead:

  12df216c61 ("x86/boot/e820: Introduce the bootloader provided e820_table_firmware[] table")

Originally the kexec_file_load and kexec_load syscalls both used 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 the kexec_load and kexec_file_load syscalls 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 this change was made
a year ago:

  fc7f27cda8 ("x86/kexec: Do not update E820 kexec table for setup_data")

[ mingo: Tidy up the changelog and comments. ]

Signed-off-by: Dave Young <dyoung@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Ashish Kalra <ashish.kalra@amd.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Joerg Roedel <jroedel@suse.de>
Cc: Baoquan He <bhe@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Link: https://lore.kernel.org/r/Z5jcb1GKhLvH8kDc@darkstar.users.ipa.redhat.com
This commit is contained in:
Dave Young 2025-01-28 21:32:31 +08:00 • committed by Ingo Molnar
parent 5bebe2e4fe
commit a2498e5c45
2 changed files with 10 additions and 11 deletions
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20
arch/x86/kernel/e820.c
View file

@ -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 an 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 the kexec kernel.
*
* kexec_file_load in-kernel code uses the table for the 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.
@ -1117,9 +1117,9 @@ void __init e820__reserve_resources(void)
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));
}

1
arch/x86/virt/svm/sev.c
View file

@ -198,7 +198,6 @@ static void __init __snp_fixup_e820_tables(u64 pa)
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);
}