From: Matt Fleming <matt@console-pimps.org>
To: Bart Kuivenhoven <bemk@redhat.com>
Cc: matt.fleming@intel.com, hpa@zytor.com, tglx@linutronix.de,
mingo@redhat.com, x86@kernel.org, linux-efi@vger.kernel.org,
linux-kernel@vger.kernel.org, jcm@redhat.com, msalter@redhat.com
Subject: Re: [PATCH] x86 efi: bugfix interrupt disabling sequence
Date: Fri, 20 Sep 2013 16:28:59 +0100 [thread overview]
Message-ID: <20130920152859.GC21381@console-pimps.org> (raw)
In-Reply-To: <1379525333-4373-1-git-send-email-bemk@redhat.com>
On Wed, 18 Sep, at 07:28:53PM, Bart Kuivenhoven wrote:
> The problem in efi_main was that the idt was cleared before the
> interrupts were disabled.
>
> The UEFI spec states that interrupts aren't used so this shouldn't be
> too much of a problem. Peripherals however don't necessarily know about
> this and thus might cause interrupts to happen anyway. Even if
> ExitBootServices() has been called.
>
> This means there is a risk of an interrupt being triggered while the IDT
> register is nullified and the interrupt bit hasn't been cleared,
> allowing for a triple fault.
Just to be clear, you haven't witnessed a triple fault, correct?
> This patch fixes this by clearing the interrupt bit before the lidt
> instruction.
I think we can go even further than this and get rid of all of the IDT
code in the EFI boot stub. The kernel maintains its own IDT anyway.
--
Matt Fleming, Intel Open Source Technology Center
next prev parent reply other threads:[~2013-09-20 15:29 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-18 17:28 [PATCH] x86 efi: bugfix interrupt disabling sequence Bart Kuivenhoven
2013-09-20 15:28 ` Matt Fleming [this message]
2013-09-20 20:21 ` Bart Kuivenhoven
2013-09-21 7:50 ` Ingo Molnar
2013-09-21 15:41 ` Matt Fleming
2013-09-23 9:27 ` Bart Kuivenhoven
-- strict thread matches above, loose matches on Subject: below --
2013-09-23 9:45 Bart Kuivenhoven
2013-09-25 13:12 ` Matt Fleming
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