Re: [Xen-devel] IOMMU initialization failure when using linux-as-bootloader

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 27.08.16 at 12:40, <s.munaut@xxxxxxxxxxxxxxxxxxxx> wrote:
> I'll test this in more detail next week to make sure things really
> work as expected (atm I'm just testing if dom0 boots properly). And if
> things turn OK and you think this is a proper fix for the issue and
> safe to apply, I can send the patch properly to the list.

I think this is reasonable, despite it certainly being unexpected for
the BIOS to turn such on when not putting the system into x2APIC
mode. Considering you're not talking about a BIOS here, may I
nevertheless ask why it's not instead Linux/kexec which get fixed
to not leave these features enabled before handing off control?

Jan

> --- a/xen/drivers/passthrough/vtd/iommu.c
> +++ b/xen/drivers/passthrough/vtd/iommu.c
> @@ -2102,6 +2102,9 @@ static int __must_check init_vtd_hw(void)
> 
>          clear_fault_bits(iommu);
> 
> +        disable_intremap(iommu);
> +        disable_qinval(iommu);
> +
>          spin_lock_irqsave(&iommu->register_lock, flags);
>          sts = dmar_readl(iommu->reg, DMAR_FECTL_REG);
>          sts &= ~DMA_FECTL_IM;



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