From: Jason Gunthorpe <jgg@nvidia.com>
To: Alex Williamson <alex.williamson@redhat.com>
Cc: <cohuck@redhat.com>, <kvm@vger.kernel.org>,
<linux-kernel@vger.kernel.org>, <peterx@redhat.com>
Subject: Re: [RFC PATCH 04/10] vfio/pci: Use vfio_device_unmap_mapping_range()
Date: Mon, 22 Feb 2021 13:22:30 -0400 [thread overview]
Message-ID: <20210222172230.GO4247@nvidia.com> (raw)
In-Reply-To: <161401267316.16443.11184767955094847849.stgit@gimli.home>
On Mon, Feb 22, 2021 at 09:51:13AM -0700, Alex Williamson wrote:
> + vfio_device_unmap_mapping_range(vdev->device,
> + VFIO_PCI_INDEX_TO_OFFSET(VFIO_PCI_BAR0_REGION_INDEX),
> + VFIO_PCI_INDEX_TO_OFFSET(VFIO_PCI_ROM_REGION_INDEX) -
> + VFIO_PCI_INDEX_TO_OFFSET(VFIO_PCI_BAR0_REGION_INDEX));
Isn't this the same as invalidating everything? I see in
vfio_pci_mmap():
if (index >= VFIO_PCI_ROM_REGION_INDEX)
return -EINVAL;
> @@ -2273,15 +2112,13 @@ static int vfio_pci_try_zap_and_vma_lock_cb(struct pci_dev *pdev, void *data)
>
> vdev = vfio_device_data(device);
>
> - /*
> - * Locking multiple devices is prone to deadlock, runaway and
> - * unwind if we hit contention.
> - */
> - if (!vfio_pci_zap_and_vma_lock(vdev, true)) {
> + if (!down_write_trylock(&vdev->memory_lock)) {
> vfio_device_put(device);
> return -EBUSY;
> }
And this is only done as part of VFIO_DEVICE_PCI_HOT_RESET?
It looks like VFIO_DEVICE_PCI_HOT_RESET effects the entire slot?
How about putting the inode on the reflck structure, which is also
per-slot, and then a single unmap_mapping_range() will take care of
everything, no need to iterate over things in the driver core.
Note the vm->pg_off space doesn't have any special meaning, it is
fine that two struct vfio_pci_device's are sharing the same address
space and using an incompatible overlapping pg_offs
> diff --git a/drivers/vfio/pci/vfio_pci_private.h b/drivers/vfio/pci/vfio_pci_private.h
> index 9cd1882a05af..ba37f4eeefd0 100644
> +++ b/drivers/vfio/pci/vfio_pci_private.h
> @@ -101,6 +101,7 @@ struct vfio_pci_mmap_vma {
>
> struct vfio_pci_device {
> struct pci_dev *pdev;
> + struct vfio_device *device;
Ah, I did this too, but I didn't use a pointer :)
All the places trying to call vfio_device_put() when they really want
a vfio_pci_device * become simpler now. Eg struct vfio_devices wants
to have an array of vfio_pci_device, and get_pf_vdev() only needs to
return one pointer.
Jason
next prev parent reply other threads:[~2021-02-22 17:23 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-22 16:50 [RFC PATCH 00/10] vfio: Device memory DMA mapping improvements Alex Williamson
2021-02-22 16:50 ` [RFC PATCH 01/10] vfio: Create vfio_fs_type with inode per device Alex Williamson
2021-02-26 5:38 ` Christoph Hellwig
2021-02-26 13:15 ` Jason Gunthorpe
2021-02-22 16:50 ` [RFC PATCH 02/10] vfio: Update vfio_add_group_dev() API Alex Williamson
2021-02-22 17:01 ` Jason Gunthorpe
2021-02-22 16:50 ` [RFC PATCH 03/10] vfio: Export unmap_mapping_range() wrapper Alex Williamson
2021-02-22 16:51 ` [RFC PATCH 04/10] vfio/pci: Use vfio_device_unmap_mapping_range() Alex Williamson
2021-02-22 17:22 ` Jason Gunthorpe [this message]
2021-02-24 21:55 ` Alex Williamson
2021-02-25 0:57 ` Jason Gunthorpe
2021-02-22 16:51 ` [RFC PATCH 05/10] vfio: Create a vfio_device from vma lookup Alex Williamson
2021-02-22 17:29 ` Jason Gunthorpe
2021-02-24 21:55 ` Alex Williamson
2021-02-25 0:06 ` Jason Gunthorpe
2021-02-25 22:21 ` Alex Williamson
2021-02-25 23:49 ` Jason Gunthorpe
2021-03-04 21:37 ` Alex Williamson
2021-03-04 23:16 ` Jason Gunthorpe
2021-03-05 0:07 ` Alex Williamson
2021-03-05 0:36 ` Jason Gunthorpe
2021-02-22 16:51 ` [RFC PATCH 06/10] vfio: Add a device notifier interface Alex Williamson
2021-02-22 16:51 ` [RFC PATCH 07/10] vfio/pci: Notify on device release Alex Williamson
2021-02-22 16:52 ` [RFC PATCH 08/10] vfio/type1: Refactor pfn_list clearing Alex Williamson
2021-02-22 16:52 ` [RFC PATCH 09/10] vfio/type1: Pass iommu and dma objects through to vaddr_get_pfn Alex Williamson
2021-02-22 16:52 ` [RFC PATCH 10/10] vfio/type1: Register device notifier Alex Williamson
2021-02-22 17:55 ` Jason Gunthorpe
2021-02-24 21:55 ` Alex Williamson
2021-02-25 0:22 ` Jason Gunthorpe
2021-02-25 17:54 ` Peter Xu
2021-02-25 18:19 ` Jason Gunthorpe
2021-02-25 19:06 ` Peter Xu
2021-02-25 19:17 ` Jason Gunthorpe
2021-02-25 19:54 ` Peter Xu
2021-02-26 5:47 ` Christoph Hellwig
2021-02-22 18:00 ` [RFC PATCH 00/10] vfio: Device memory DMA mapping improvements Jason Gunthorpe
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