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Re: [Qemu-devel] [PATCH 6/6] xen-pt: Round pci regions sizes to XEN_PAGE
From: |
Andrew Cooper |
Subject: |
Re: [Qemu-devel] [PATCH 6/6] xen-pt: Round pci regions sizes to XEN_PAGE_SIZE |
Date: |
Thu, 14 Mar 2019 19:37:21 +0000 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.1 |
On 14/03/2019 19:22, Simon Gaiser wrote:
> Jason Andryuk:
>> On Wed, Mar 13, 2019 at 11:09 AM Paul Durrant <address@hidden> wrote:
>>>> -----Original Message-----
>>>> From: Jason Andryuk [mailto:address@hidden
>>>> Sent: 11 March 2019 18:02
>>>> To: address@hidden
>>>> Cc: address@hidden; address@hidden; Simon Gaiser
>>>> <address@hidden>; Jason Andryuk <address@hidden>; Stefano Stabellini
>>>> <address@hidden>; Anthony Perard <address@hidden>; Paul Durrant
>>>> <address@hidden>
>>>> Subject: [PATCH 6/6] xen-pt: Round pci regions sizes to XEN_PAGE_SIZE
>>>>
>>>> From: Simon Gaiser <address@hidden>
>>>>
>>>> If a pci memory region has a size < XEN_PAGE_SIZE it can get located at
>>>> an address which is not page aligned.
>>> IIRC the PCI spec says that the minimum memory region size should be at
>>> least 4k. Should we even be tolerating BARs smaller than that?
>>>
>>> Paul
>>>
>> Hi, Paul.
>>
>> Simon found this, so it affects a real device. Simon, do you recall
>> which device was affected?
> Not sure which one it was. Probably the USB controller or the SD host
> controller. As your example below shows this is not so uncommon.
The minimum is 128 bytes, not 4k - I've just checked the PCIe spec.
Xen/Qemu definitely needs to cope with smaller than 4k if we want to be
spec compliant.
~Andrew
- Re: [Qemu-devel] [Xen-devel] [PATCH 5/6] xen-pt: Hide MSI-X from xen stubdoms, (continued)
- [Qemu-devel] [PATCH 6/6] xen-pt: Round pci regions sizes to XEN_PAGE_SIZE, Jason Andryuk, 2019/03/11
- Re: [Qemu-devel] [PATCH 6/6] xen-pt: Round pci regions sizes to XEN_PAGE_SIZE, Simon Gaiser, 2019/03/14
- Re: [Qemu-devel] [PATCH 6/6] xen-pt: Round pci regions sizes to XEN_PAGE_SIZE, Paul Durrant, 2019/03/15
- Re: [Qemu-devel] [Xen-devel] [PATCH 6/6] xen-pt: Round pci regions sizes to XEN_PAGE_SIZE, Andrew Cooper, 2019/03/15
- Re: [Qemu-devel] [Xen-devel] [PATCH 6/6] xen-pt: Round pci regions sizes to XEN_PAGE_SIZE, Jason Andryuk, 2019/03/20
- Re: [Qemu-devel] [Xen-devel] [PATCH 6/6] xen-pt: Round pci regions sizes to XEN_PAGE_SIZE, Roger Pau Monné, 2019/03/21
- Re: [Qemu-devel] [Xen-devel] [PATCH 6/6] xen-pt: Round pci regions sizes to XEN_PAGE_SIZE, Jason Andryuk, 2019/03/22