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Date: Mon, 25 Apr 2016 12:21:18 +0200
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Subject: Re: [PATCHv2 0/6] efi: detect erroneous firmware IRQ manipulation
From: Ard Biesheuvel <ard.biesheuvel@linaro.org>
To: Matt Fleming <matt@codeblueprint.co.uk>, Laszlo Ersek <lersek@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
        "linux-efi@vger.kernel.org" <linux-efi@vger.kernel.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
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        Leif Lindholm <leif.lindholm@linaro.org>,
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        Will Deacon <will.deacon@arm.com>
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(+ Laszlo)

On 25 April 2016 at 12:15, Matt Fleming <matt@codeblueprint.co.uk> wrote:
> On Sun, 24 Apr, at 10:22:41PM, Matt Fleming wrote:
>>
>> I like this series a lot (well, ignoring the fact that the firmware is
>> trying to eat itself). The runtime call code is much cleaner now, and
>> this is a great precedent for any future multi-architecture quirks we
>> may need.
>>
>> Queued for v4.7, thanks everyone!
>
> Hmm... Booting this series with Qemu and OVMF results in lots of
> warnings,
>
> [ 0.102173] ------------[ cut here ]------------
> [ 0.103000] WARNING: CPU: 0 PID: 0 at /dev/shm/mfleming/git/efi/drivers/firmware/efi/runtime-wrappers.c:30 efi_call_virt_check_flags+0x69/0x90
> [ 0.103505] Modules linked in:
> [ 0.104519] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.6.0-rc4+ #1
> [    0.105000]  0000000000000000 ffffffff81e03e30 ffffffff8132206f 0000000000000000
> [    0.105000]  0000000000000000 ffffffff81e03e70 ffffffff8105a47c 0000001e0000000a
> [    0.105000]  0000000000000246 0000000000000286 ffffffff81bed975 ffffffff81e03f10
> [    0.105000] Call Trace:
> [    0.105000]  [<ffffffff8132206f>] dump_stack+0x4d/0x6e
> [    0.105000]  [<ffffffff8105a47c>] __warn+0xcc/0xf0
> [    0.105000]  [<ffffffff8105a558>] warn_slowpath_null+0x18/0x20
> [    0.105000]  [<ffffffff8164e5a9>] efi_call_virt_check_flags+0x69/0x90
> [    0.105000]  [<ffffffff8164f9d2>] virt_efi_set_variable+0x82/0x190
> [    0.105000]  [<ffffffff81054555>] efi_delete_dummy_variable+0x75/0x80
> [    0.105000]  [<ffffffff81f599f6>] efi_enter_virtual_mode+0x463/0x472
> [    0.105000]  [<ffffffff81f41f82>] start_kernel+0x38f/0x415
> [    0.105000]  [<ffffffff81f419e1>] ? set_init_arg+0x55/0x55
> [    0.105000]  [<ffffffff81f415ee>] x86_64_start_reservations+0x2a/0x2c
> [    0.105000]  [<ffffffff81f416da>] x86_64_start_kernel+0xea/0xed
> [    0.107181] ---[ end trace 0081cc453369d969 ]---
> [    0.107499] Disabling lock debugging due to kernel taint
> [    0.108226] [Firmware Bug]: IRQ flags corrupted (0x00000246=>0x00000286) by EFI set_variable
>
> Has anyone tested this series on x86 to ensure that this is a rare
> case? I'll go and test some physical x86 machines now.

I suppose that it is quite likely that this issue occurs in the wild
if it is present in OVMF. Could anyone check which flag is actually
clobbered here?