1. 29 Jul, 2022 1 commit
    • Thadeu Lima de Souza Cascardo's avatar
      x86/bugs: Do not enable IBPB at firmware entry when IBPB is not available · 571c30b1
      Thadeu Lima de Souza Cascardo authored
      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: 28a99e95 ("x86/amd: Use IBPB for firmware calls")
      Reported-by: default avatarDimitri John Ledkov <dimitri.ledkov@canonical.com>
      Signed-off-by: default avatarThadeu Lima de Souza Cascardo <cascardo@canonical.com>
      Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
      Cc: <stable@vger.kernel.org>
      Link: https://lore.kernel.org/r/20220728122602.2500509-1-cascardo@canonical.com
      571c30b1
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