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From: Christoph Hellwig <hch@infradead.org>
To: Peter Xu <peterx@redhat.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>,
	Alex Williamson <alex.williamson@redhat.com>,
	kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
	prime.zeng@hisilicon.com, cohuck@redhat.com
Subject: Re: [PATCH] vfio/pci: Handle concurrent vma faults
Date: Thu, 11 Mar 2021 11:35:24 +0000	[thread overview]
Message-ID: <20210311113524.GA1726872@infradead.org> (raw)
In-Reply-To: <20210310200607.GG6530@xz-x1>

On Wed, Mar 10, 2021 at 03:06:07PM -0500, Peter Xu wrote:
> On Wed, Mar 10, 2021 at 02:40:11PM -0400, Jason Gunthorpe wrote:
> > On Wed, Mar 10, 2021 at 11:34:06AM -0700, Alex Williamson wrote:
> > 
> > > > I think after the address_space changes this should try to stick with
> > > > a normal io_rmap_pfn_range() done outside the fault handler.
> > > 
> > > I assume you're suggesting calling io_remap_pfn_range() when device
> > > memory is enabled,
> > 
> > Yes, I think I saw Peter thinking along these lines too
> > 
> > Then fault just always causes SIGBUS if it gets called

I feel much more comfortable having the io_remap_pfn_range in place.

> 
> Indeed that looks better than looping in the fault().
> 
> But I don't know whether it'll be easy to move io_remap_pfn_range() to device
> memory enablement.  If it's a two-step thing, we can fix the BUG_ON and vma
> duplication issue first, then the full rework can be done in the bigger series
> as what be chosen as the last approach.

What kind of problems do you envision?  It seems pretty simple to do,
at least when combined with the unmap_mapping_range patch.

  reply	other threads:[~2021-03-11 11:36 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-10 17:53 [PATCH] vfio/pci: Handle concurrent vma faults Alex Williamson
2021-03-10 18:14 ` Jason Gunthorpe
2021-03-10 18:34   ` Alex Williamson
2021-03-10 18:40     ` Jason Gunthorpe
2021-03-10 20:06       ` Peter Xu
2021-03-11 11:35         ` Christoph Hellwig [this message]
2021-03-11 16:35           ` Peter Xu
2021-03-12 19:16       ` Alex Williamson
2021-03-12 19:41         ` Jason Gunthorpe
2021-03-12 20:09           ` Alex Williamson
2021-03-12 20:58             ` Alex Williamson
2021-03-13  0:03               ` Jason Gunthorpe

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