Re: [PATCH 0/2] KVM: MMU: support VMAs that got remap_pfn_range-ed

From	Neo Jia <cjia@nvidia.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH 0/2] KVM: MMU: support VMAs that got remap_pfn_range-ed
Date	2016-07-04 09:10 +0200
Message-ID	<rR6aZ-2Cq-29@gated-at.bofh.it> (permalink)
References	<rPJTb-1y9-7@gated-at.bofh.it> <rR5RE-2gx-7@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Mon, Jul 04, 2016 at 02:39:22PM +0800, Xiao Guangrong wrote:
> 
> 
> On 06/30/2016 09:01 PM, 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.
> 
> Why does it require fetching the pfn when the fault is triggered rather
> than when mmap() is called?

Hi Guangrong,

as such mapping information between virtual mmio to physical mmio is only available 
at runtime.

> 
> Why the memory mapped by this mmap() is not a portion of MMIO from
> underlayer physical device? If it is a valid system memory, is this interface
> really needed to implemented in vfio? (you at least need to set VM_MIXEDMAP
> if it mixed system memory with MMIO)
> 

It actually is a portion of the physical mmio which is set by vfio mmap.

> IIUC, the kernel assumes that VM_PFNMAP is a continuous memory, e.g, like
> current KVM and vaddr_get_pfn() in vfio, but it seems nvdia's patchset
> breaks this semantic as ops->validate_map_request() can adjust the physical
> address arbitrarily. (again, the name 'validate' should be changed to match
> the thing as it is really doing)

The vgpu api will allow you to adjust the target mmio address and the size via 
validate_map_request, but it is still physical contiguous as <start_pfn, size>.

Thanks,
Neo

> 
>

Thread

[PATCH 0/2] KVM: MMU: support VMAs that got remap_pfn_range-ed Paolo Bonzini <pbonzini@redhat.com> - 2016-06-30 15:10 +0200
  [PATCH 1/2] KVM: MMU: prepare to support mapping of VM_IO and VM_PFNMAP frames Paolo Bonzini <pbonzini@redhat.com> - 2016-06-30 15:10 +0200
  Re: [PATCH 0/2] KVM: MMU: support VMAs that got remap_pfn_range-ed Neo Jia <cjia@nvidia.com> - 2016-07-01 00:10 +0200
  Re: [PATCH 0/2] KVM: MMU: support VMAs that got remap_pfn_range-ed Xiao Guangrong <guangrong.xiao@linux.intel.com> - 2016-07-04 08:50 +0200
    Re: [PATCH 0/2] KVM: MMU: support VMAs that got remap_pfn_range-ed Neo Jia <cjia@nvidia.com> - 2016-07-04 09:10 +0200
      Re: [PATCH 0/2] KVM: MMU: support VMAs that got remap_pfn_range-ed Xiao Guangrong <guangrong.xiao@linux.intel.com> - 2016-07-04 09:50 +0200
        Re: [PATCH 0/2] KVM: MMU: support VMAs that got remap_pfn_range-ed Paolo Bonzini <pbonzini@redhat.com> - 2016-07-04 09:50 +0200
          Re: [PATCH 0/2] KVM: MMU: support VMAs that got remap_pfn_range-ed Xiao Guangrong <guangrong.xiao@linux.intel.com> - 2016-07-04 10:10 +0200
            Re: [PATCH 0/2] KVM: MMU: support VMAs that got remap_pfn_range-ed Paolo Bonzini <pbonzini@redhat.com> - 2016-07-04 10:20 +0200
              Re: [PATCH 0/2] KVM: MMU: support VMAs that got remap_pfn_range-ed Xiao Guangrong <guangrong.xiao@linux.intel.com> - 2016-07-04 10:30 +0200
                Re: [PATCH 0/2] KVM: MMU: support VMAs that got remap_pfn_range-ed Paolo Bonzini <pbonzini@redhat.com> - 2016-07-04 10:50 +0200
        Re: [PATCH 0/2] KVM: MMU: support VMAs that got remap_pfn_range-ed Neo Jia <cjia@nvidia.com> - 2016-07-04 10:00 +0200
          Re: [PATCH 0/2] KVM: MMU: support VMAs that got remap_pfn_range-ed Neo Jia <cjia@nvidia.com> - 2016-07-04 17:40 +0200
            Re: [PATCH 0/2] KVM: MMU: support VMAs that got remap_pfn_range-ed Xiao Guangrong <guangrong.xiao@linux.intel.com> - 2016-07-05 03:30 +0200
              Re: [PATCH 0/2] KVM: MMU: support VMAs that got remap_pfn_range-ed Neo Jia <cjia@nvidia.com> - 2016-07-05 03:40 +0200
                Re: [PATCH 0/2] KVM: MMU: support VMAs that got remap_pfn_range-ed Xiao Guangrong <guangrong.xiao@linux.intel.com> - 2016-07-05 06:10 +0200
                Re: [PATCH 0/2] KVM: MMU: support VMAs that got remap_pfn_range-ed Neo Jia <cjia@nvidia.com> - 2016-07-05 07:20 +0200
                Re: [PATCH 0/2] KVM: MMU: support VMAs that got remap_pfn_range-ed Xiao Guangrong <guangrong.xiao@linux.intel.com> - 2016-07-05 08:40 +0200
                Re: [PATCH 0/2] KVM: MMU: support VMAs that got remap_pfn_range-ed Neo Jia <cjia@nvidia.com> - 2016-07-05 09:40 +0200
                Re: [PATCH 0/2] KVM: MMU: support VMAs that got remap_pfn_range-ed Xiao Guangrong <guangrong.xiao@linux.intel.com> - 2016-07-05 11:10 +0200
                Re: [PATCH 0/2] KVM: MMU: support VMAs that got remap_pfn_range-ed Neo Jia <cjia@nvidia.com> - 2016-07-05 17:10 +0200
                Re: [PATCH 0/2] KVM: MMU: support VMAs that got remap_pfn_range-ed Xiao Guangrong <guangrong.xiao@linux.intel.com> - 2016-07-06 04:30 +0200
                Re: [PATCH 0/2] KVM: MMU: support VMAs that got remap_pfn_range-ed Neo Jia <cjia@nvidia.com> - 2016-07-06 06:10 +0200
          Re: [PATCH 0/2] KVM: MMU: support VMAs that got remap_pfn_range-ed Xiao Guangrong <guangrong.xiao@linux.intel.com> - 2016-07-04 10:30 +0200
            Re: [PATCH 0/2] KVM: MMU: support VMAs that got remap_pfn_range-ed Xiao Guangrong <guangrong.xiao@linux.intel.com> - 2016-07-04 12:30 +0200
            Re: [PATCH 0/2] KVM: MMU: support VMAs that got remap_pfn_range-ed Neo Jia <cjia@nvidia.com> - 2016-07-04 10:50 +0200
              Re: [PATCH 0/2] KVM: MMU: support VMAs that got remap_pfn_range-ed Xiao Guangrong <guangrong.xiao@linux.intel.com> - 2016-07-04 10:50 +0200
                Re: [PATCH 0/2] KVM: MMU: support VMAs that got remap_pfn_range-ed Xiao Guangrong <guangrong.xiao@linux.intel.com> - 2016-07-04 11:00 +0200
                Re: [PATCH 0/2] KVM: MMU: support VMAs that got remap_pfn_range-ed Neo Jia <cjia@nvidia.com> - 2016-07-04 11:20 +0200
    Re: [PATCH 0/2] KVM: MMU: support VMAs that got remap_pfn_range-ed Paolo Bonzini <pbonzini@redhat.com> - 2016-07-04 09:40 +0200
      Re: [PATCH 0/2] KVM: MMU: support VMAs that got remap_pfn_range-ed Xiao Guangrong <guangrong.xiao@linux.intel.com> - 2016-07-04 09:50 +0200
  Re: [PATCH 0/2] KVM: MMU: support VMAs that got remap_pfn_range-ed Neo Jia <cjia@nvidia.com> - 2016-07-05 07:50 +0200
    Re: [PATCH 0/2] KVM: MMU: support VMAs that got remap_pfn_range-ed Paolo Bonzini <pbonzini@redhat.com> - 2016-07-05 14:20 +0200
      Re: [PATCH 0/2] KVM: MMU: support VMAs that got remap_pfn_range-ed Neo Jia <cjia@nvidia.com> - 2016-07-05 16:10 +0200
      Re: [PATCH 0/2] KVM: MMU: support VMAs that got remap_pfn_range-ed Xiao Guangrong <guangrong.xiao@linux.intel.com> - 2016-07-06 04:10 +0200
        Re: [PATCH 0/2] KVM: MMU: support VMAs that got remap_pfn_range-ed Neo Jia <cjia@nvidia.com> - 2016-07-06 04:20 +0200
          Re: [PATCH 0/2] KVM: MMU: support VMAs that got remap_pfn_range-ed Xiao Guangrong <guangrong.xiao@linux.intel.com> - 2016-07-06 04:40 +0200
            Re: [PATCH 0/2] KVM: MMU: support VMAs that got remap_pfn_range-ed Neo Jia <cjia@nvidia.com> - 2016-07-06 05:00 +0200
              Re: [PATCH 0/2] KVM: MMU: support VMAs that got remap_pfn_range-ed Xiao Guangrong <guangrong.xiao@linux.intel.com> - 2016-07-06 06:10 +0200
                Re: [PATCH 0/2] KVM: MMU: support VMAs that got remap_pfn_range-ed Paolo Bonzini <pbonzini@redhat.com> - 2016-07-06 13:50 +0200
                Re: [PATCH 0/2] KVM: MMU: support VMAs that got remap_pfn_range-ed Xiao Guangrong <guangrong.xiao@linux.intel.com> - 2016-07-07 04:50 +0200
        Re: [PATCH 0/2] KVM: MMU: support VMAs that got remap_pfn_range-ed Paolo Bonzini <pbonzini@redhat.com> - 2016-07-06 08:10 +0200
          Re: [PATCH 0/2] KVM: MMU: support VMAs that got remap_pfn_range-ed Alex Williamson <alex.williamson@redhat.com> - 2016-07-06 18:00 +0200

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