From: Li RongQing Date: Tue, 19 Aug 2025 02:33:56 +0000 (+0800) Subject: x86/bugs: Fix GDS mitigation selecting when mitigation is off X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=d4932a1b148bb6121121e56bad312c4339042d70;p=users%2Fjedix%2Flinux-maple.git x86/bugs: Fix GDS mitigation selecting when mitigation is off The current GDS mitigation logic incorrectly returns early when the attack vector mitigation is turned off, which leads to two problems: 1. CPUs without ARCH_CAP_GDS_CTRL support are incorrectly marked with GDS_MITIGATION_OFF when they should be marked as GDS_MITIGATION_UCODE_NEEDED. 2. The mitigation state checks and locking verification that follow are skipped, which means: - fail to detect if the mitigation was locked - miss the warning when trying to disable a locked mitigation Remove the early return to ensure proper mitigation state handling. This allows: - Proper mitigation classification for non-ARCH_CAP_GDS_CTRL CPUs - Complete mitigation state verification This also addresses the failed MSR 0x123 write attempt at boot on non-ARCH_CAP_GDS_CTRL CPUs: unchecked MSR access error: WRMSR to 0x123 (tried to write 0x0000000000000010) at rIP: ... (update_gds_msr) Call Trace: identify_secondary_cpu start_secondary common_startup_64 WARNING: CPU: 1 PID: 0 at arch/x86/kernel/cpu/bugs.c:1053 update_gds_msr [ bp: Massage, zap superfluous braces. ] Fixes: 8c7261abcb7ad ("x86/bugs: Add attack vector controls for GDS") Suggested-by: Pawan Gupta Signed-off-by: Li RongQing Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Pawan Gupta Link: https://lore.kernel.org/20250819023356.2012-1-lirongqing@baidu.com --- diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 2186a771b9fc3..49ef1b832c1a5 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -1068,10 +1068,8 @@ static void __init gds_select_mitigation(void) if (gds_mitigation == GDS_MITIGATION_AUTO) { if (should_mitigate_vuln(X86_BUG_GDS)) gds_mitigation = GDS_MITIGATION_FULL; - else { + else gds_mitigation = GDS_MITIGATION_OFF; - return; - } } /* No microcode */