x86/kexec: Disable LASS during relocate kernel

Browse source

The relocate kernel mechanism uses an identity mapping to copy the new
kernel, which leads to a LASS violation when executing from a low
address.

LASS must be disabled after the original CR4 value is saved because
kexec paths that preserve context need to restore CR4.LASS. But,
disabling it along with CET during identity_mapped() is too late. So,
disable LASS immediately after saving CR4, along with PGE, and before
jumping to the identity-mapped page.

Signed-off-by: Sohil Mehta <sohil.mehta@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://patch.msgid.link/20251118182911.2983253-6-sohil.mehta%40intel.com

...

This commit is contained in:

Sohil Mehta 2025-11-18 10:29:07 -08:00 • committed by Dave Hansen

parent b3a7e973ab

commit 731d43750c

1 changed files with 5 additions and 2 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

7

arch/x86/kernel/relocate_kernel_64.S

View file