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

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Message-ID: <20130530221737.GA11105@sgi.com>
Date:	Thu, 30 May 2013 17:17:37 -0500
From:	Russ Anderson <rja@....com>
To:	joeyli <jlee@...e.com>
Cc:	Jiri Kosina <jkosina@...e.cz>,
	Matt Fleming <matt@...sole-pimps.org>,
	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 Thu, May 30, 2013 at 10:16:12AM +0800, joeyli wrote:
> 於 四，2013-05-30 於 00:53 +0200，Jiri Kosina 提到：
> > On Wed, 29 May 2013, Russ Anderson wrote:
> > 
> > > > 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???
> > 
> > That was my original idea early today as well. My understanding of the 
> > UEFI spec is admittedly limited, but afaics calling runtime method from 
> > boot environment should be a valid thing to do ... ?
> 
> QueryVariableInfo() is a runtime services, all runtime services should
> available bother on boot time and runtime:
> 
> UEFI spec 2.3.1 P.109:
>   Runtime Services
>   Functions that are available before and after any call to  
>   ExitBootServices(). These functions are described in Section 7.

That's a great idea.  This patch moves the QueryVariableInfo()
call from bootime to runtime, in efi_late_init().  The attached
patch is consistent with the UEFI spec and avoids the problem.

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

View attachment "efi_move_query_call.patch" of type "text/x-patch" (4165 bytes)