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Re: [Qemu-devel] [V9 0/4] AMD IOMMU

From: Valentine Sinitsyn
Subject: Re: [Qemu-devel] [V9 0/4] AMD IOMMU
Date: Wed, 4 May 2016 12:39:17 +0500
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0

Hi everyone,

On 04.05.2016 12:05, David Kiarie wrote:
On Wed, May 4, 2016 at 9:12 AM, Jan Kiszka <address@hidden> wrote:
On 2016-04-30 00:42, David Kiarie wrote:
These series adds AMD IOMMU support to Qemu. It's currently in the 9th version.

In this series I have (hopefully) addressed all the comments made in the 
previous version.
I have also tested and successfully passed-through PCI device 'ac97' with more 
devices to be tested.

I've done some basic testing with a Jailhouse setup and found it
working. The ACPI table is now properly parsed and the DMA remapping was
not disturbing the system after Jailhouse was activated.

However, it was also still not intervening after I started to corrupt
the configuration, removed DMA target properties from most of the RAM or
dropped PCI devices.
Please also remember that unlisted devices go without translation. To "mute" the device, set V, TV, the DomainId, and zero everything else in the DTE.

This means you're invalidating DTEs ?

You are not dropping invalid remapping requests, are you? According to
the logs, you are detecting them at least:

(amd-iommu)amd_iommu_get_dte: Device Table at 0x3b0d4000
(amd-iommu)amd_iommu_get_dte: Pte entry at 0x0 is invalid
(amd-iommu)amd_iommu_translate: devid: 00:02.0 gpa 0x32f39480 hpa 0x32f39000

It's a bit hard to test right now if remapping is actually properly
working in all important cases if you do not reject invalid ones.
My understanding is that you should generate an IO_PAGE_FAULT event and drop the request. This doesn't apply to ATS, which is a bit trickier, but we don't address ATS in this patch series anyway, do we?


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