From: Julien Grall <julien@xen.org>
To: Stefano Stabellini <sstabellini@kernel.org>
Cc: xen-devel@lists.xenproject.org,
Stefano Stabellini <stefano.stabellini@xilinx.com>,
Volodymyr_Babchuk@epam.com
Subject: Re: [PATCH 12/12] xen/arm: call iomem_permit_access for passthrough devices
Date: Sun, 24 May 2020 15:12:30 +0100 [thread overview]
Message-ID: <453b58f8-d9ee-bbe7-ac05-b5268620e79f@xen.org> (raw)
In-Reply-To: <f7f01eca-2415-e102-318f-0c58606fda96@xen.org>
Hi,
On 30/04/2020 14:01, Julien Grall wrote:
> On 29/04/2020 21:47, Stefano Stabellini wrote:
>> On Wed, 15 Apr 2020, Julien Grall wrote: But doesn't it make sense to
>> give domU permission if it is going to get
>> the memory mapped? But admittedly I can't think of something that would
>> break because of the lack of the iomem_permit_access call in this code
>> path.
>
> On Arm, the permissions are only useful if you plan you DomU to delegate
> the regions to another domain. As your domain is not even aware it is
> running on Xen (we don't expose 'xen' node in the DT), it makes little
> sense to add the permission.
I actually found one use when helping a user last week. You can dump the
list of MMIO regions assigned to a guest from Xen Console.
This will use d->iomem_caps that is modified via iomem_permit_access().
Without it, there is no easy way to confirm the list of MMIO regions
assigned to a guest. Although...
> Even today, you can map IOMEM to a DomU and then revert the permission
> right after. They IOMEM will still be mapped in the guest and it will
> act normaly.
... this would not help the case where permissions are reverted. But I
am assuming this shouldn't happen for Dom0less.
Stefano, I am not sure what's your plan for the series itself for Xen
4.14. I think this patch could go in now. Any thoughts?
Cheers,
--
Julien Grall
next prev parent reply other threads:[~2020-05-24 14:13 UTC|newest]
Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-15 1:02 [PATCH 0/12] direct-map DomUs Stefano Stabellini
2020-04-15 1:02 ` [PATCH 01/12] xen: introduce xen_dom_flags Stefano Stabellini
2020-04-15 9:12 ` Jan Beulich
2020-04-15 13:26 ` Julien Grall
2020-04-29 23:57 ` Stefano Stabellini
2020-04-15 1:02 ` [PATCH 02/12] xen/arm: introduce arch_xen_dom_flags and direct_map Stefano Stabellini
2020-04-15 10:27 ` Jan Beulich
2020-04-15 11:27 ` Andrew Cooper
2020-04-30 0:34 ` Stefano Stabellini
2020-04-15 1:02 ` [PATCH 03/12] xen/arm: introduce 1:1 mapping for domUs Stefano Stabellini
2020-04-15 13:36 ` Julien Grall
2020-05-01 1:26 ` Stefano Stabellini
2020-05-01 8:30 ` Julien Grall
2020-05-09 0:07 ` Stefano Stabellini
2020-05-09 9:56 ` Julien Grall
2020-04-15 1:02 ` [PATCH 04/12] xen: split alloc_heap_pages in two halves for reusability Stefano Stabellini
2020-04-15 11:22 ` Wei Liu
2020-04-17 10:02 ` Jan Beulich
2020-04-29 23:09 ` Stefano Stabellini
2020-04-15 1:02 ` [PATCH 05/12] xen: introduce reserve_heap_pages Stefano Stabellini
2020-04-15 13:24 ` Julien Grall
2020-04-17 10:11 ` Jan Beulich
2020-04-29 22:46 ` Stefano Stabellini
2020-04-30 6:29 ` Jan Beulich
2020-04-30 16:21 ` Stefano Stabellini
2020-05-04 9:16 ` Jan Beulich
2020-04-30 14:51 ` Julien Grall
2020-04-30 17:00 ` Stefano Stabellini
2020-04-30 18:27 ` Julien Grall
2020-05-12 1:10 ` Stefano Stabellini
2020-05-12 8:57 ` Julien Grall
2020-04-15 1:02 ` [PATCH 06/12] xen/arm: reserve 1:1 memory for direct_map domUs Stefano Stabellini
2020-04-15 13:38 ` Julien Grall
2020-04-15 1:02 ` [PATCH 07/12] xen/arm: new vgic: rename vgic_cpu/dist_base to c/dbase Stefano Stabellini
2020-04-15 13:41 ` Julien Grall
2020-04-15 1:02 ` [PATCH 08/12] xen/arm: if is_domain_direct_mapped use native addresses for GICv2 Stefano Stabellini
2020-04-15 14:00 ` Julien Grall
2020-05-01 1:26 ` Stefano Stabellini
2020-05-01 8:23 ` Julien Grall
2020-05-09 0:06 ` Stefano Stabellini
2020-04-15 1:02 ` [PATCH 09/12] xen/arm: if is_domain_direct_mapped use native addresses for GICv3 Stefano Stabellini
2020-04-15 14:09 ` Julien Grall
2020-05-01 1:31 ` Stefano Stabellini
2020-05-01 8:40 ` Julien Grall
2020-05-09 0:06 ` Stefano Stabellini
2020-04-15 1:02 ` [PATCH 10/12] xen/arm: if is_domain_direct_mapped use native UART address for vPL011 Stefano Stabellini
2020-04-15 14:11 ` Julien Grall
2020-05-01 1:26 ` Stefano Stabellini
2020-05-01 8:09 ` Julien Grall
2020-05-09 0:07 ` Stefano Stabellini
2020-05-09 10:11 ` Julien Grall
2020-05-11 22:58 ` Stefano Stabellini
2020-04-15 1:02 ` [PATCH 11/12] xen/arm: if xen_force don't try to setup the IOMMU Stefano Stabellini
2020-04-15 14:12 ` Julien Grall
2020-04-29 21:55 ` Stefano Stabellini
2020-04-30 13:51 ` Julien Grall
2020-05-01 1:25 ` Stefano Stabellini
2020-04-15 1:02 ` [PATCH 12/12] xen/arm: call iomem_permit_access for passthrough devices Stefano Stabellini
2020-04-15 14:18 ` Julien Grall
2020-04-29 20:47 ` Stefano Stabellini
2020-04-30 13:01 ` Julien Grall
2020-05-24 14:12 ` Julien Grall [this message]
2020-05-26 16:46 ` Stefano Stabellini
2020-05-27 18:09 ` Julien Grall
2020-04-16 8:59 ` [PATCH 0/12] direct-map DomUs Julien Grall
2020-04-29 20:16 ` Stefano Stabellini
2020-04-30 12:54 ` Julien Grall
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