Re: [regression, bisected] x86: efi: Pass boot services variableinfo to runtime code

From: Russ Anderson
Date: Wed May 29 2013 - 18:47:00 EST


On Thu, May 30, 2013 at 12:22:13AM +0200, Jiri Kosina wrote:
> On Wed, 29 May 2013, Russ Anderson wrote:
>
> > > 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 does trigger the problem. Note that the definition of
> > QueryVariableInfo() in the UEFI spec says:
> >
> > The returned MaximumVariableStorageSize, RemainingVariableStorageSize,
> > MaximumVariableSize information may change immediately after the call
> > based on other runtime activities including asynchronous error events.
> > Also, these values associated with different attributes are not
> > additive in nature.
> >
> > Note the values may be accurate at the point in time when returned,
> > but may not be after that.
> >
> > After the system has transitioned into runtime (after
> > ExitBootServices() is called), an implementation may not be able to
> > accurately return information about the Boot Services variable store.
> > In such cases, EFI_INVALID_PARAMETER should be returned.
> >
> > It is not clear to me exactly when ExitBootServices() is called.
> > Our bios is returning a failing indication on the call.
>
> Yes, but this call is clearly happening way before ExitBootServices() --
> see the surrounding code, see for example this in efi_main():
>
> [ ... snip ... ]
> setup_efi_vars(boot_params);
>
> setup_efi_pci(boot_params);
>
> status = efi_call_phys3(sys_table->boottime->allocate_pool,
> EFI_LOADER_DATA, sizeof(*gdt),
> (void **)&gdt);
> if (status != EFI_SUCCESS) {
> efi_printk("Failed to alloc mem for gdt structure\n");
> goto fail;
> }
> [ ... snip ... ]

Yes. Note the failing call is sys_table->runtime while all the
other calls are sys_table->boottime and seem to work. Not sure
why the sys_table->runtime call has a problem but it may be
a clue. Could something in the runtime path not be set up???

> We are calling QueryVariableInfo() in setup_efi_vars(), and later on
> AllocatePool is being called (through boot table).

On my system the QueryVariableInfo() call fails, so AllocatePool()
is not called in setup_efi_vars().

> That'd inherently fail
> if we were calling it after ExitBootServices() has happened, but I believe
> that call is succeeding on your affected system as well.
>
> --
> Jiri Kosina
> SUSE Labs

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