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
Subject: Re: [PATCH v2 1/3] vfio/type1: Support faulting PFNMAP vmas
Date: Thu, 7 May 2020 17:24:43 -0400 [thread overview]
Message-ID: <20200507212443.GO228260@xz-x1> (raw)
In-Reply-To: <158871568480.15589.17339878308143043906.stgit@gimli.home>
On Tue, May 05, 2020 at 03:54:44PM -0600, Alex Williamson wrote:
> With conversion to follow_pfn(), DMA mapping a PFNMAP range depends on
> the range being faulted into the vma. Add support to manually provide
> that, in the same way as done on KVM with hva_to_pfn_remapped().
>
> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
> ---
> drivers/vfio/vfio_iommu_type1.c | 36 +++++++++++++++++++++++++++++++++---
> 1 file changed, 33 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> index cc1d64765ce7..4a4cb7cd86b2 100644
> --- a/drivers/vfio/vfio_iommu_type1.c
> +++ b/drivers/vfio/vfio_iommu_type1.c
> @@ -317,6 +317,32 @@ static int put_pfn(unsigned long pfn, int prot)
> return 0;
> }
>
> +static int follow_fault_pfn(struct vm_area_struct *vma, struct mm_struct *mm,
> + unsigned long vaddr, unsigned long *pfn,
> + bool write_fault)
> +{
> + int ret;
> +
> + ret = follow_pfn(vma, vaddr, pfn);
> + if (ret) {
> + bool unlocked = false;
> +
> + ret = fixup_user_fault(NULL, mm, vaddr,
> + FAULT_FLAG_REMOTE |
> + (write_fault ? FAULT_FLAG_WRITE : 0),
> + &unlocked);
> + if (unlocked)
> + return -EAGAIN;
Hi, Alex,
IIUC this retry is not needed too because fixup_user_fault() will guarantee the
fault-in is done correctly with the valid PTE as long as ret==0, even if
unlocked==true.
Note: there's another patch just removed the similar retry in kvm:
https://lore.kernel.org/kvm/20200416155906.267462-1-peterx@redhat.com/
Thanks,
> +
> + if (ret)
> + return ret;
> +
> + ret = follow_pfn(vma, vaddr, pfn);
> + }
> +
> + return ret;
> +}
--
Peter Xu
next prev parent reply other threads:[~2020-05-07 21:24 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-05 21:54 [PATCH v2 0/3] vfio-pci: Block user access to disabled device MMIO Alex Williamson
2020-05-05 21:54 ` [PATCH v2 1/3] vfio/type1: Support faulting PFNMAP vmas Alex Williamson
2020-05-07 21:24 ` Peter Xu [this message]
2020-05-07 21:47 ` Alex Williamson
2020-05-07 23:54 ` Jason Gunthorpe
2020-05-08 2:19 ` Peter Xu
2020-05-08 12:10 ` Jason Gunthorpe
2020-05-08 14:30 ` Peter Xu
2020-05-08 15:05 ` Jason Gunthorpe
2020-05-08 15:42 ` Alex Williamson
2020-05-08 16:05 ` Peter Xu
2020-05-08 18:39 ` Peter Xu
2020-05-05 21:54 ` [PATCH v2 2/3] vfio-pci: Fault mmaps to enable vma tracking Alex Williamson
2020-05-07 21:47 ` Peter Xu
2020-05-07 22:03 ` Alex Williamson
2020-05-07 22:22 ` Peter Xu
2020-05-07 23:56 ` Jason Gunthorpe
2020-05-08 2:16 ` Peter Xu
2020-05-08 6:44 ` Jason Wang
2020-05-08 14:27 ` Peter Xu
2020-05-08 12:08 ` Jason Gunthorpe
2020-05-08 14:26 ` Peter Xu
2020-05-05 21:55 ` [PATCH v2 3/3] vfio-pci: Invalidate mmaps and block MMIO access on disabled memory Alex Williamson
2020-05-22 2:39 ` Qian Cai
2020-05-22 4:18 ` Alex Williamson
2020-05-07 21:59 ` [PATCH v2 0/3] vfio-pci: Block user access to disabled device MMIO Peter Xu
2020-05-07 22:34 ` Alex Williamson
2020-05-08 2:31 ` Peter Xu
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