Re: [PATCH/RFC] PCI prepare/activate instead of enable to avoid IRQstorm and rogue DMA access

[Tejun Heo]

Andi Kleen wrote:
> Tejun Heo <htejun@xxxxxxxxx> writes:
> > Let's assume there's a device which shares its INTX IRQ line with
> > another device and the other one is already initialized.  During boot,
> > due to BIOS's fault, bad hardware design or sheer bad luck, the device
> > has got a pending IRQ.
>
> This seems to be also common after kexec during kexec crashdumps
> where the device just continues doing what it did before the crash.
>
> > This patch expands the pci_set_master() approach.  Instead of enabling
> > the device in one go, it's done in two steps - prepare and activate.
> > 'prepare' enables access to PCI configuration,
>
> I hope there aren't any new erratas triggered by this. Perhaps it would
> make sense to add some paranoia sleeps at least before touching other
> state? 

Do you mean between disabling IRQ mechanisms and enabling PCI device in 
pcim_prepare_device()?

Thanks.

--
tejun
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