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Re: Linux pin_user_pages_fast fails on Xen
- To: Stefano Stabellini <stefano.stabellini@xxxxxxx>, "NK, JESHWANTHKUMAR (JESHWANTH KUMAR)" <JESHWANTHKUMAR.NK@xxxxxxx>
- From: Jan Beulich <jbeulich@xxxxxxxx>
- Date: Wed, 14 Sep 2022 08:48:27 +0200
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- Cc: "boris.ostrovsky@xxxxxxxxxx" <boris.ostrovsky@xxxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>, "Rangasamy, Devaraj" <Devaraj.Rangasamy@xxxxxxx>, "Pandeshwara krishna, Mythri" <Mythri.Pandeshwarakrishna@xxxxxxx>, "SK, SivaSangeetha (Siva Sangeetha)" <SivaSangeetha.SK@xxxxxxx>, "Thomas, Rijo-john" <Rijo-john.Thomas@xxxxxxx>, "jgross@xxxxxxxx" <jgross@xxxxxxxx>
- Delivery-date: Wed, 14 Sep 2022 06:48:36 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 14.09.2022 01:31, Stefano Stabellini wrote:
> The problem is that drivers/xen/privcmd.c:privcmd_mmap sets VM_IO |
> VM_PFNMAP, and either flag would cause check_vma_flags to return
> -EFAULT.
>
> Do you know if it works if you remove VM_IO | VM_PFNMAP from
> privcmd_mmap?
My Linux MM knowledge is certainly rusty, but I don't think this can
work, at the very least not without further changes elsewhere. I did
look some at the specific use by the TEE subsystem, and it looks to
me as if their "shared memory" machinery simply isn't meant to be
used with non-local memory.
Jan
|
