linux-kernel - Re: [regression, bisected] x86: efi: Pass boot services variable info to runtime code

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Date:	Fri, 24 May 2013 15:05:39 -0500
From:	Russ Anderson <rja@....com>
To:	Matt Fleming <matt@...sole-pimps.org>
Cc:	Matthew Garrett <matthew.garrett@...ula.com>,
	matt.fleming@...el.com, linux-efi@...r.kernel.org, x86@...nel.org,
	linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...ux.intel.com>,
	Borislav Petkov <bp@...en8.de>
Subject: Re: [regression, bisected] x86: efi: Pass boot services variable
 info to runtime code

On Fri, May 24, 2013 at 08:43:31AM +0100, Matt Fleming wrote:
> On Thu, 23 May, at 03:32:34PM, Russ Anderson wrote:
> >    efi: mem127: type=4, attr=0xf, range=[0x000000006bb22000-0x000000007ca9c000) (271MB)
> 
> EFI_BOOT_SERVICES_CODE
> 
> >    efi: mem133: type=5, attr=0x800000000000000f, range=[0x000000007daff000-0x000000007dbff000) (1MB)
> 
> EFI_RUNTIME_SERVICES_CODE
> 
> >    EFI Variables Facility v0.08 2004-May-17
> >    BUG: unable to handle kernel paging request at 000000007ca95b10
> >    IP: [<ffff88007dbf2140>] 0xffff88007dbf213f
> 
> >     [<ffffffff810499b3>] ?  efi_call3+0x43/0x80
> >     [<ffffffff810492a7>] ?  virt_efi_get_next_variable+0x47/0x1c0
> >     [<ffffffff814c8cc0>] ?  create_efivars_bin_attributes+0x150/0x150
> >     [<ffffffff814c7b55>] ?  efivar_init+0xd5/0x390
> >     [<ffffffff814c8ae0>] ?  efivar_update_sysfs_entries+0x90/0x90
> >     [<ffffffff812f906b>] ?  kobject_uevent+0xb/0x10
> >     [<ffffffff812f812b>] ?  kset_register+0x5b/0x70
> >     [<ffffffff814c8cc0>] ?  create_efivars_bin_attributes+0x150/0x150
> >     [<ffffffff814c8d47>] ?  efivars_sysfs_init+0x87/0xf0
> >     [<ffffffff8100032a>] ?  do_one_initcall+0x15a/0x1b0
> >     [<ffffffff81a17831>] ?  do_basic_setup+0xad/0xce
> >     [<ffffffff81a17ae3>] ?  kernel_init_freeable+0x291/0x291
> >     [<ffffffff81a3708a>] ?  sched_init_smp+0x15b/0x162
> >     [<ffffffff81a17a5f>] ?  kernel_init_freeable+0x20d/0x291
> >     [<ffffffff81601eb0>] ?  rest_init+0x80/0x80
> >     [<ffffffff81601ebe>] ?  kernel_init+0xe/0x180
> >     [<ffffffff8162179c>] ?  ret_from_fork+0x7c/0xb0
> >     [<ffffffff81601eb0>] ?  rest_init+0x80/0x80
> 
> Here's the real call stack leading up to the crash.
> 
> What appears to be happening is that your the EFI runtime services code
> is calling into the EFI boot services code, which is definitely a bug in
> your firmware because we're at runtime, but we've seen other machines
> that do similar things so we usually handle it just fine. However, what
> makes your case different, and the reason you see the above splat, is
> that it's using the physical address of the EFI boot services region,
> not the virtual one we setup with SetVirtualAddressMap(). Which is a
> second firmware bug. Again, we have seen other machines that access
> physical addresses after SetVirtualAddressMap(), but until now we
> haven't had any non-optional code that triggered them.
> 
> The only reason I can see that the offending commit would introduce this
> problem is because it calls QueryVariableInfo() at boot time. I notice
> that your machine is an SGI UV one, is there any chance you could get a
> firmware fix for this? If possible, it would be also good to confirm
> that it's this chunk of code in setup_efi_vars(),
> 
> 	status = efi_call_phys4(sys_table->runtime->query_variable_info,
> 				EFI_VARIABLE_NON_VOLATILE |
> 				EFI_VARIABLE_BOOTSERVICE_ACCESS |
> 				EFI_VARIABLE_RUNTIME_ACCESS, &store_size,
> 				&remaining_size, &var_size);

This call is failing, but not returning a valid EFI_* return status.
setup_efi_vars() returns at that point.  Maybe it is not set up
to do GetNextVariable() later on???  Why call GetNextVariable() if the
earlier call failed?

> that later makes GetNextVariable() jump to the physical address of the
> EFI Boot Services region. Because if not, we need to do some more
> digging.

One other data point is if the query_variable_info call is hacked to
remove one of the EFI flags (ie comment out EFI_VARIABLE_BOOTSERVICE_ACCESS)
the efi_call_phys4() call fails with EFI_INVALID_PARAMETER and
the system boots.  Of course it does not create /sys/firmware/efivars
entries and complains "[Firmware Bug]: efi: Inconsistent initial sizes".
But at least it boots.

One of the BIOS guys will build a debug bios next week to help see
what is going on in the query_variable_info() call.

> Borislav, how are your 1:1 mapping patches coming along? In theory, once
> those are merged we can gracefully workaround these kinds of issues.
> 
> -- 
> Matt Fleming, Intel Open Source Technology Center

-- 
Russ Anderson, OS RAS/Partitioning Project Lead  
SGI - Silicon Graphics Inc          rja@....com
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