linux-kernel - Re: [PATCH 02/14] x86-64/efi: Use EFI to deal with platform wall clock (again)

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Date:	Thu, 19 Dec 2013 10:49:08 +0000
From:	Matt Fleming <matt@...sole-pimps.org>
To:	"Lee, Chun-Yi" <joeyli.kernel@...il.com>
Cc:	JBeulich@...e.com, linux-kernel@...r.kernel.org,
	rtc-linux@...glegroups.com, x86@...nel.org,
	"linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>,
	linux-acpi@...r.kernel.org, Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	"H. Peter Anvin" <hpa@...or.com>,
	Matt Fleming <matt.fleming@...el.com>
Subject: Re: [PATCH 02/14] x86-64/efi: Use EFI to deal with platform wall
 clock (again)

On Thu, 19 Dec, at 06:20:16PM, Lee, Chun-Yi wrote:
> From: Jan Beulich <JBeulich@...e.com>
> 
> Other than ix86, x86-64 on EFI so far didn't set the
> {g,s}et_wallclock accessors to the EFI routines, thus
> incorrectly using raw RTC accesses instead.
> 
> Simply removing the #ifdef around the respective code isn't
> enough, however: While so far early get-time calls were done in
> physical mode, this doesn't work properly for x86-64, as virtual
> addresses would still need to be set up for all runtime regions
> (which wasn't the case on the system I have access to), so
> instead the patch moves the call to efi_enter_virtual_mode()
> ahead (which in turn allows to drop all code related to calling
> efi-get-time in physical mode).
> 
> Additionally the earlier calling of efi_set_executable()
> requires the CPA code to cope, i.e. during early boot it must be
> avoided to call cpa_flush_array(), as the first thing this
> function does is a BUG_ON(irqs_disabled()).
> 
> Also make the two EFI functions in question here static -
> they're not being referenced elsewhere.
> 
> History:
> 
>     This commit was originally merged as bacef661acdb ("x86-64/efi:
>     Use EFI to deal with platform wall clock") but it resulted in some
>     ASUS machines no longer booting due to a firmware bug, and so was
>     reverted in f026cfa82f62.
> 
>     Then a pre-emptive fix for the buggy ASUS firmware was merged in
>     03a1c254975e ("x86, efi: 1:1 pagetable mapping for virtual EFI
>     calls") but it causes odd bootup problems on x86-64. So this patch
>     revoked again by 11520e5e7c1.
> 
>     Now Borislav Petkov's "EFI runtime services virtual mapping" is
>     merged to EFI 'next' branch. So this patch can be reapplied again.
> 
> Signed-off-by: Jan Beulich <jbeulich@...e.com>
> Tested-by: Matt Fleming <matt.fleming@...el.com>
> Acked-by: Matthew Garrett <mjg@...hat.com>
> Cc: Ingo Molnar <mingo@...nel.org>
> Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
> Cc: H. Peter Anvin <hpa@...or.com>
> Signed-off-by: Matt Fleming <matt.fleming@...el.com> [added commit history]
> Acked-by: Lee, Chun-Yi <jlee@...e.com>
> ---
>  arch/x86/mm/pageattr.c      |   10 ++++++----
>  arch/x86/platform/efi/efi.c |   35 +++++++++++------------------------
>  include/linux/efi.h         |    2 --
>  init/main.c                 |    8 ++++----
>  4 files changed, 21 insertions(+), 34 deletions(-)

Lee, you can't just simply resend this patch with all the tags - I
haven't tested this version with any recent changes and I'm pretty sure
Matthew isn't going to Ack it.

Do you know if anyone has tested this patch with Borislav's recent
changes?

-- 
Matt Fleming, Intel Open Source Technology Center
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