linux-kernel - Re: [PATCH 0/2] KVM: MMU: support VMAs that got remap_pfn

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Date:	Mon, 4 Jul 2016 22:41:48 -0700
From:	Neo Jia <cjia@...dia.com>
To:	Paolo Bonzini <pbonzini@...hat.com>
CC:	<linux-kernel@...r.kernel.org>, <kvm@...r.kernel.org>,
	Kirti Wankhede <kwankhede@...dia.com>,
	Xiao Guangrong <guangrong.xiao@...ux.intel.com>,
	Andrea Arcangeli <aarcange@...hat.com>,
	Radim Krčmář <rkrcmar@...hat.com>
Subject: Re: [PATCH 0/2] KVM: MMU: support VMAs that got remap_pfn_range-ed

On Thu, Jun 30, 2016 at 03:01:49PM +0200, Paolo Bonzini wrote:
> The vGPU folks would like to trap the first access to a BAR by setting
> vm_ops on the VMAs produced by mmap-ing a VFIO device.  The fault handler
> then can use remap_pfn_range to place some non-reserved pages in the VMA.
> 
> KVM lacks support for this kind of non-linear VM_PFNMAP mapping, and these
> patches should fix this.

Hi Paolo,

I have tested your patches with the mediated passthru patchset that is being
reviewed in KVM and QEMU mailing list.

The fault handler gets called successfully and the previously mapped memory gets
unmmaped correctly via unmap_mapping_range.

Thanks,
Neo

> 
> Thanks,
> 
> Paolo
> 
> Paolo Bonzini (2):
>   KVM: MMU: prepare to support mapping of VM_IO and VM_PFNMAP frames
>   KVM: MMU: try to fix up page faults before giving up
> 
>  mm/gup.c            |  1 +
>  virt/kvm/kvm_main.c | 55 ++++++++++++++++++++++++++++++++++++++++++++++++-----
>  2 files changed, 51 insertions(+), 5 deletions(-)
> 
> -- 
> 1.8.3.1
>