From: Peter Xu <peterx@redhat.com>
To: Alex Williamson <alex.williamson@redhat.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
cohuck@redhat.com, jgg@ziepe.ca, cai@lca.pw
Subject: Re: [PATCH v3 3/3] vfio-pci: Invalidate mmaps and block MMIO access on disabled memory
Date: Sat, 23 May 2020 15:34:17 -0400 [thread overview]
Message-ID: <20200523193417.GI766834@xz-x1> (raw)
In-Reply-To: <159017506369.18853.17306023099999811263.stgit@gimli.home>
Hi, Alex,
On Fri, May 22, 2020 at 01:17:43PM -0600, Alex Williamson wrote:
> @@ -1346,15 +1526,32 @@ static vm_fault_t vfio_pci_mmap_fault(struct vm_fault *vmf)
> {
> struct vm_area_struct *vma = vmf->vma;
> struct vfio_pci_device *vdev = vma->vm_private_data;
> + vm_fault_t ret = VM_FAULT_NOPAGE;
> +
> + mutex_lock(&vdev->vma_lock);
> + down_read(&vdev->memory_lock);
I remembered to have seen the fault() handling FAULT_FLAG_RETRY_NOWAIT at least
in the very first version, but it's not here any more... Could I ask what's
the reason behind? I probably have missed something along with the versions,
I'm just not sure whether e.g. this would potentially block a GUP caller even
if it's with FOLL_NOWAIT.
Side note: Another thing I thought about when reading this patch - there seems
to have quite some possibility that the VFIO_DEVICE_PCI_HOT_RESET ioctl will
start to return -EBUSY now. Not a problem for this series, but maybe we should
rememeber to let the userspace handle -EBUSY properly as follow up too, since I
saw QEMU seemed to not handle -EBUSY for host reset path right now.
Thanks,
--
Peter Xu
next prev parent reply other threads:[~2020-05-23 19:34 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-22 19:17 [PATCH v3 0/3] vfio-pci: Block user access to disabled device MMIO Alex Williamson
2020-05-22 19:17 ` [PATCH v3 1/3] vfio/type1: Support faulting PFNMAP vmas Alex Williamson
2020-05-22 19:17 ` [PATCH v3 2/3] vfio-pci: Fault mmaps to enable vma tracking Alex Williamson
2020-05-22 19:17 ` [PATCH v3 3/3] vfio-pci: Invalidate mmaps and block MMIO access on disabled memory Alex Williamson
2020-05-23 19:34 ` Peter Xu [this message]
2020-05-23 23:06 ` Alex Williamson
2020-05-23 23:52 ` Peter Xu
2020-05-24 0:02 ` Peter Xu
2020-05-25 12:26 ` Jason Gunthorpe
2020-05-25 14:28 ` Peter Xu
2020-05-25 14:46 ` Jason Gunthorpe
2020-05-25 15:11 ` Peter Xu
2020-05-25 16:56 ` Jason Gunthorpe
2020-05-25 20:56 ` John Hubbard
2020-05-26 0:37 ` Jason Gunthorpe
2020-05-26 0:46 ` John Hubbard
2020-05-26 13:49 ` Peter Xu
2020-05-26 14:32 ` Alex Williamson
2020-05-26 14:46 ` Peter Xu
2020-05-26 15:53 ` Jason Gunthorpe
2020-05-26 15:57 ` Alex Williamson
2020-05-22 22:08 ` [PATCH v3 0/3] vfio-pci: Block user access to disabled device MMIO Qian Cai
2020-05-22 22:25 ` Alex Williamson
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