Re: [Xen-devel] dom0 as pvh boot problem

[Elena Ufimtseva <ufimtseva@xxxxxxxxx>]

On Tue, Jan 6, 2015 at 10:39 PM, Zhang, Yang Z <yang.z.zhang@xxxxxxxxx> wrote:

Elena Ufimtseva wrote on 2015-01-07:

>
>
> On Mon, Jan 5, 2015 at 7:53 AM, Zhang, Yang Z <yang.z.zhang@xxxxxxxxx>
> wrote:
>
>
>Â Â Â ÂJan Beulich wrote on 2015-01-05:
>
>Â Â Â Â>>>> Elena Ufimtseva <ufimtseva@xxxxxxxxx> 01/02/15 7:32 PM >>>Â Â Â Â Â>> The
> last successful command is the reading status register of second   >>
> IOMMU    Â>> unit:    >>   >> <snip from iommu_enable_translation() in  Â>>
> ./xen/drivers/passthrough/vtd/iommu.c>Â Â Â Â >>Â Â Â >> 746:Â Â sts =
> dmar_readl(iommu->reg, DMAR_GSTS_REG); 747:Â Â>> dmar_writel(iommu->reg,
> DMAR_GCMD_REG, sts | DMA_GCMD_TE);Â Â >>Â Â Â >> </snip>Â Â Â >>Â Â Â >> After
> dmar_writel for second iommu the machine hangs.   Â>   Â> That's rather odd
> - you say it doesn't even reach the IOMMU_WAIT_OP()Â Â> right after that?
> That would suggest a fault or other abnormal > condition raised by the
> translation enabling (i.e. some problem with > the page tables, albeit
> that should then have been a problem for the first IOMMU already).  >
> Yet an eventual fault can't be delivered at that point due to    Â>
> interrupts being disabled. Perhaps the VT-d maintainers (now Cc-ed)Â Â>
> have some suggestion as to what's going on or how to diagnose.
>
>
>Â Â Â ÂI am curious why pv dom0 boot fine. Will pvh dom0 share EPT table
> with VT-d? Maybe try with disable sharing to see whether helps.
>
>
>
> Yes, it is interesting. I am working on pvh guest boot under pv dom0.

Hi Yang

Somehow I dropped the list from this conversation. Adding back.
Â

We can start from this point. It is not very hard to find the difference on
IOMMU setup when booting pvh dom0 and pv dom0. Also, have you seen
any difference on IOMMU register on working and non-working case?

I compared the registers and I did not find any difference in pv or pvh case.

I did it for both iommus, before enabling each unit and after. They are the same.

If you would like, I can post the dumps.

As for the differences between setting up iommu, I will check and get back with this.

Thank you for your advice.

Â

>
> I tried booting with non shared EPTs, but with the same result.
>
>
>
>
>Â Â Â Â>
>Â Â Â Â> Jan
>
>
>Â Â Â ÂBest regards,
>Â Â Â ÂYang
>
>
>
>
>
>


Best regards,
Yang

--

Elena

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