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Date: Mon, 02 Feb 2015 16:23:56 +0000
From: Marc Zyngier <marc.zyngier@....com>
To: Bjorn Helgaas <bhelgaas@...gle.com>
CC: Thomas Gleixner <tglx@...utronix.de>,
Jiang Liu <jiang.liu@...ux.intel.com>,
Lorenzo Pieralisi <Lorenzo.Pieralisi@....com>,
Andre Przywara <Andre.Przywara@....com>,
"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
linux-arm <linux-arm-kernel@...ts.infradead.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] PCI: Fix pcibios_update_irq misuse of irq number
On 02/02/15 15:57, Bjorn Helgaas wrote:
> On Wed, Jan 28, 2015 at 8:51 AM, Marc Zyngier <marc.zyngier@....com> wrote:
>> pcibios_update_irq writes an irq number into the config space
>> of a given PCI device, but ignores the fact that this number
>> is a virtual interrupt number, which might be a very different
>> value from what the underlying hardware is using.
>>
>> The obvious fix is to fetch the HW interrupt number from the
>> corresponding irq_data structure. This is slightly complicated
>> by the fact that this interrupt might be services by a stacked
>> domain.
>>
>> This has been tested on KVM with kvmtool.
>>
>> Reported-by: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
>> Tested-by: Andre Przywara <andre.przywara@....com>
>> Signed-off-by: Marc Zyngier <marc.zyngier@....com>
>
> Jiang, are you OK with this patch as-is now, since it isn't used on x86?
>
> Marc, Lorenzo, I assume this actually fixes a bug. Can we get any
> more details about what happens when you hit the bug, and how you
> reproduced it (what platform, driver, etc.)?
It definitely fixes a bug. This has been found by running a KVM guest
using kvmtool PCI emulation, where the following things happen:
- Guest programs a virtual (bogus) interrupt number in the PCI device
config space (virtio disk in this case)
- kvmtool uses that interrupt number as is, without any other form of
validation
- Either the injection fails (because the interrupt is out of the range
of the virtual interrupt controller) -> virtio PCI device goes dead
- or the injection succeeds because this is a valid interrupt number,
but signals an unrelated peripheral -> virtio PCI device goes dead.
This can be trivially reproduced on any ARM PCI system that requires
legacy interrupts (i.e. no MSI support), and that uses a GIC interrupt
controller. Doing it in a VM is just much more convenient.
Hope this helps,
M.
--
Jazz is not dead. It just smells funny...
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