From: Thadeu Lima de Souza Cascardo cascardo@canonical.com
commit 571c30b1a88465a1c85a6f7762609939b9085a15 upstream.
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/kernel/cpu/bugs.c | 1 + 1 file changed, 1 insertion(+)
--- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -1513,6 +1513,7 @@ static void __init spectre_v2_select_mit * 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)) {