x86/bugs: Add AMD retbleed= boot parameter
commit
7fbf47c7ce50b38a64576b150e7011ae73d54669 upstream.
Add the "retbleed=<value>" boot parameter to select a mitigation for
RETBleed. Possible values are "off", "auto" and "unret"
(JMP2RET mitigation). The default value is "auto".
Currently, "retbleed=auto" will select the unret mitigation on
AMD and Hygon and no mitigation on Intel (JMP2RET is not effective on
Intel).
[peterz: rebase; add hygon]
[jpoimboe: cleanups]
Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
[ bp: Adjust context - no jmp2ret mitigation exists ]
Signed-off-by: Suraj Jitindar Singh <surajjs@amazon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>