From: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Date: Thu, 28 Jul 2022 09:26:02 -0300
Subject: x86/bugs: Do not enable IBPB at firmware entry when IBPB is not
available
Git-commit: 571c30b1a88465a1c85a6f7762609939b9085a15
Patch-mainline: v5.19
References: git-fixes
Some cloud hypervisors do not provide IBPB on very recent CPU processors,
including AMD processors affected by Retbleed.
Using IBPB before firmware calls on such systems would cause a GPF at boot
like the one below. Do not enable such calls when IBPB support is not
present.
EFI Variables Facility v0.08 2004-May-17
general protection fault, maybe for address 0x1: 0000 [#1] PREEMPT SMP NOPTI
CPU: 0 PID: 24 Comm: kworker/u2:1 Not tainted 5.19.0-rc8+ #7
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 0.0.0 02/06/2015
Workqueue: efi_rts_wq efi_call_rts
RIP: 0010:efi_call_rts
Code: e8 37 33 58 ff 41 bf 48 00 00 00 49 89 c0 44 89 f9 48 83 c8 01 4c 89 c2 48 c1 ea 20 66 90 b9 49 00 00 00 b8 01 00 00 00 31 d2 <0f> 30 e8 7b 9f 5d ff e8 f6 f8 ff ff 4c 89 f1 4c 89 ea 4c 89 e6 48
RSP: 0018:ffffb373800d7e38 EFLAGS: 00010246
RAX: 0000000000000001 RBX: 0000000000000006 RCX: 0000000000000049
RDX: 0000000000000000 RSI: ffff94fbc19d8fe0 RDI: ffff94fbc1b2b300
RBP: ffffb373800d7e70 R08: 0000000000000000 R09: 0000000000000000
R10: 000000000000000b R11: 000000000000000b R12: ffffb3738001fd78
R13: ffff94fbc2fcfc00 R14: ffffb3738001fd80 R15: 0000000000000048
FS: 0000000000000000(0000) GS:ffff94fc3da00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffff94fc30201000 CR3: 000000006f610000 CR4: 00000000000406f0
Call Trace:
<TASK>
? __wake_up
process_one_work
worker_thread
? rescuer_thread
kthread
? kthread_complete_and_exit
ret_from_fork
</TASK>
Modules linked in:
Fixes: 28a99e95f55c ("x86/amd: Use IBPB for firmware calls")
Reported-by: Dimitri John Ledkov <dimitri.ledkov@canonical.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20220728122602.2500509-1-cascardo@canonical.com
Acked-by: Nikolay Borisov <nik.borisov@suse.com>
---
arch/x86/kernel/cpu/bugs.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 6454bc767f0f..6761668100b9 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -1520,6 +1520,7 @@ static void __init spectre_v2_select_mitigation(void)
* enable IBRS around firmware calls.
*/
if (boot_cpu_has_bug(X86_BUG_RETBLEED) &&
+ boot_cpu_has(X86_FEATURE_IBPB) &&
(boot_cpu_data.x86_vendor == X86_VENDOR_AMD ||
boot_cpu_data.x86_vendor == X86_VENDOR_HYGON)) {