Regarding the vfio_device_info struct: I get 9 device regions, of which
region 0, 2 and 4 seem to be the three BAR regions. Is that so? Always?
What do the other regions do?
And by mmap of PCIe config space you mean mapping the files
/sys/bus/pci/devices/0000:xx:yy.z/resource0 ?!
Thanks a lot!
Oliver
------------------------------------------------------------------------
*From:* Alex Williamson <mailto:alex.william...@redhat.com>
*Sent:* Tuesday, January 30, 2018 10:00PM
*To:* Heid, Oliver <mailto:oliver.h...@h-next.de>
*Cc:* Vfio-users <mailto:vfio-users@redhat.com>
*Subject:* Re: [vfio-users] VFIO for PCIe streaming from/to user space
On Tue, 30 Jan 2018 21:41:30 +0100
Oliver Heid <oliver.h...@h-next.de> wrote:
So the userspace -> IOVA mapping is not done automatically?
No, see the API, user provides an IOVA.
How do I get
the MMU entries of user's pages from userspace and write them into the
IOMMU?
You don't need them, provide the virtual address to the mapping ioctl.
For instance if your buffer is mmap'd, provide the mmap pointer.
Isn't it quite a security hazard to let any user program the IOMMU?
Any user cannot program the IOMMU, only users with permissions granted
to access the vfio group file and only up to the locked page limit
allowed for that user. Thanks,
Alex
------------------------------------------------------------------------
*From:* Alex Williamson <mailto:alex.william...@redhat.com>
*Sent:* Tuesday, January 30, 2018 4:06PM
*To:* Heid, Oliver <mailto:oliver.h...@h-next.de>
*Cc:* Vfio-users <mailto:vfio-users@redhat.com>
*Subject:* Re: [vfio-users] VFIO for PCIe streaming from/to user space
On Tue, 30 Jan 2018 12:02:32 +0100
Oliver Heid <oliver.h...@h-next.de> wrote:
Hi,
I want to user VFIO for direct streaming between user space and a PCIe
device (FPGA). Device isolation works, but how do I re-assign the PCIe
BARs to my user space memory and handle the IOMMU TLB remapping? Or is
there some other/better way to do that?
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/vfio.txt
PCI BARs are exposed as regions within the device file descriptor, you
can read/write to them via the file descriptor or mmap them into the
user address space where supported. DMA is configured via ioctls on
the container, mapping a user virtual address to an IOVA. Note that
some IOMMUs do not support a full 64bit IOVA space, so don't expect to
be able to identity map the IOVA to the virtual address. We're working
on an API to expose to the IOVA ranges to userspace. Thanks,
Alex
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