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Re: [XEN PATCH v1] xen/arm : Add support for SMMUv3 driver

To: Oleksandr Andrushchenko <andr2000@xxxxxxxxx>

From: Bertrand Marquis <Bertrand.Marquis@xxxxxxx>

Date: Mon, 2 Nov 2020 09:55:28 +0000

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Cc: Julien Grall <julien@xxxxxxx>, Oleksandr Andrushchenko <Oleksandr_Andrushchenko@xxxxxxxx>, Rahul Singh <Rahul.Singh@xxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>, Jan Beulich <jbeulich@xxxxxxxx>, Paul Durrant <paul@xxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>

Delivery-date: Mon, 02 Nov 2020 09:56:04 +0000

List-id: Xen developer discussion <xen-devel.lists.xenproject.org>

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Thread-topic: [XEN PATCH v1] xen/arm : Add support for SMMUv3 driver

Hi, > On 2 Nov 2020, at 05:55, Oleksandr Andrushchenko <andr2000@xxxxxxxxx> wrote: > > Hi, Julien! > > On 10/30/20 7:18 PM, Julien Grall wrote: >> Hi Oleksandr, >> >> On 30/10/2020 10:44, Oleksandr Andrushchenko wrote: >>> On 10/20/20 6:25 PM, Rahul Singh wrote: >>>> Add support for ARM architected SMMUv3 implementations. It is based on >>>> the Linux SMMUv3 driver. >>>> >>>> Major differences between the Linux driver are as follows: >>>> 1. Only Stage-2 translation is supported as compared to the Linux driver >>>> that supports both Stage-1 and Stage-2 translations. >>> >>> First of all thank you for the efforts! >>> >>> I tried the patch with QEMU and would like to know if my understanding >>> correct >>> >>> that this combination will not work as of now: >>> >>> (XEN) SMMUv3: /smmuv3@9050000: SMMUv3: DT value = eventq >>> (XEN) Data Abort Trap. Syndrome=0x1940010 >>> (XEN) Walking Hypervisor VA 0x40031000 on CPU0 via TTBR 0x00000000b8469000 >>> (XEN) 0TH[0x0] = 0x00000000b8468f7f >>> >>> [snip] >>> >>> If this is expected then is there any plan to make QEMU work as well? >>> >>> I see [1] says that "Only stage 1 and AArch64 PTW are supported." on QEMU >>> side. >> >> Just for clarication, you are trying to boot Xen on QEMU, right? > Exactly >> >> You might be able to use the stage-1 page-tables to isolate each device in >> Xen. However, I don't think you will be able to share the P2M because the >> page-tables layout between stage-1 and stage-2 is different. > So, it is even more work then Overall it would make more sense to spend some time adding proper support in Qemu then trying to modify the driver to support Qemu right now. >> >>> >>> >>> We are interested in QEMU/SMMUv3 as a flexible platform for PCI passthrough >>> >>> implementation, so it could allow testing different setups and >>> configurations with QEMU. >> >> I would recommend to get the SMMU supporting supporting stage-2 page-tables. > You mean in QEMU? See before. >> >> Regardless that, I think Xen should be able to say the SMMU is not supported >> rather than crashing. > Yes, that would be nice Fully agree and we will look into that. Anything you could share so that we could quickly reproduce your setup would be more then great. Regards Bertrand >> >> Cheers, >> > Thank you, > > Oleksandr

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