Re: [PATCH v7 1/1] vfio/nvgpu: Add vfio pci variant module for grace hopper

[Alex Williamson <alex.williamson@redhat.com>]

On Wed, 23 Aug 2023 14:50:31 +0000
Ankit Agrawal <ankita@nvidia.com> wrote:

> >> +     if (index == VFIO_PCI_BAR2_REGION_INDEX) {
> >> +             if (!nvdev->opregion) {
> >> +                     nvdev->opregion = memremap(nvdev->hpa, nvdev->mem_length, MEMREMAP_WB);
> >> +                     if (!nvdev->opregion)
> >> +                             return -ENOMEM;
> >> +             }  
> >
> > [AW] Seems like this would be susceptible to concurrent accesses causing
> > duplicate mappings.
> >
> > [JG] Needs some kind of locking on opregion  
> 
> Right, will add a new lock item in nvdev to control the access to opregion/memmap.
> Please let me know if it is preferable to do memremap in open_device instead of
> read/write.

That's a valid option also, certainly avoids the locking and
serialization per access.  Thanks,

Alex