iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

x86/bugs: Do IBPB fallback check only once

Browse Source 
When booting with retbleed=auto, if the kernel wasn't built with
CONFIG_CC_HAS_RETURN_THUNK, the mitigation falls back to IBPB.  Make
sure a warning is printed in that case.  The IBPB fallback check is done
twice, but it really only needs to be done once.

Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
This commit is contained in:
Josh Poimboeuf 2022-06-14 15:07:19 -07:00 committed by Borislav Petkov
parent 3ebc170068
commit 0fe4aeea9c
1 changed files with 5 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
arch/x86/kernel/cpu/bugs.c
View File

@ -891,18 +891,13 @@ static void __init retbleed_select_mitigation(void)
case RETBLEED_CMD_AUTO:
default:
if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD ||
boot_cpu_data.x86_vendor == X86_VENDOR_HYGON) {
if (IS_ENABLED(CONFIG_RETPOLINE) &&
IS_ENABLED(CONFIG_CC_HAS_RETURN_THUNK))
retbleed_mitigation = RETBLEED_MITIGATION_UNRET;
else
retbleed_mitigation = RETBLEED_MITIGATION_IBPB;
}
boot_cpu_data.x86_vendor == X86_VENDOR_HYGON)
retbleed_mitigation = RETBLEED_MITIGATION_UNRET;
/*
* The Intel mitigation (IBRS) was already selected in
* spectre_v2_select_mitigation().
* The Intel mitigation (IBRS or eIBRS) was already selected in
* spectre_v2_select_mitigation(). 'retbleed_mitigation' will
* be set accordingly below.
*/
break;