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	2016-07-05 03:40 +0200
Message-ID	<rRnvb-4E3-5@gated-at.bofh.it> (permalink)
References	(5 earlier) <rR7JM-3ot-25@gated-at.bofh.it> <rR8cO-3NA-27@gated-at.bofh.it> <rR9iy-4q7-7@gated-at.bofh.it> <rRe8x-7mI-9@gated-at.bofh.it> <rRnlw-4AT-23@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Tue, Jul 05, 2016 at 09:19:40AM +0800, Xiao Guangrong wrote:
> 
> 
> On 07/04/2016 11:33 PM, Neo Jia wrote:
> 
> >>>
> >>>Sorry, I think I misread the "allocation" as "mapping". We only delay the
> >>>cpu mapping, not the allocation.
> >>
> >>So how to understand your statement:
> >>"at that moment nobody has any knowledge about how the physical mmio gets virtualized"
> >>
> >>The resource, physical MMIO region, has been allocated, why we do not know the physical
> >>address mapped to the VM?
> >>
> >
> >>From a device driver point of view, the physical mmio region never gets allocated until
> >the corresponding resource is requested by clients and granted by the mediated device driver.
> 
> Hmm... but you told me that you did not delay the allocation. :(

Hi Guangrong,

The allocation here is the allocation of device resource, and the only way to
access that kind of device resource is via a mmio region of some pages there.

For example, if VM needs resource A, and the only way to access resource A is
via some kind of device memory at mmio address X.

So, we never defer the allocation request during runtime, we just setup the
CPU mapping later when it actually gets accessed.

> 
> So it returns to my original question: why not allocate the physical mmio region in mmap()?
> 

Without running anything inside the VM, how do you know how the hw resource gets
allocated, therefore no knowledge of the use of mmio region.

Thanks,
Neo

> 
> 
> 
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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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