Re: [Xen-devel] [PATCH v6 10/34] x86, x86/mm, x86/xen, olpc: Use __va() against just the physical address in cr3

From	Andrew Cooper <andrew.cooper3@citrix.com>
Newsgroups	linux.kernel
Subject	Re: [Xen-devel] [PATCH v6 10/34] x86, x86/mm, x86/xen, olpc: Use __va() against just the physical address in cr3
Date	2017-06-09 21:00 +0200
Message-ID	<tQxiy-59d-17@gated-at.bofh.it> (permalink)
References	(5 earlier) <tQd0u-11f-13@gated-at.bofh.it> <tQd0u-11f-11@gated-at.bofh.it> <tQdMS-1yv-11@gated-at.bofh.it> <tQx8R-55Y-7@gated-at.bofh.it> <tQx8R-55Y-5@gated-at.bofh.it>
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On 09/06/17 19:43, Boris Ostrovsky wrote:
> On 06/09/2017 02:36 PM, Tom Lendacky wrote:
>>> basis, although (as far as I am aware) Xen as a whole would be able to
>>> encompass itself and all of its PV guests inside one single SME
>>> instance.
>> Yes, that is correct.

Thinking more about this, it would only be possible if all the PV guests
were SME-aware and understood not to choke when it finds a frame with a
high address bit set.

I expect the only viable way to implement this (should we wish) is to
have PV guests explicitly signal support (probably via an ELF note),
after which it needs to know about the existence of SME, the meaning of
the encrypted bit in PTEs, and to defer all configuration responsibility
to Xen.

~Andrew

Thread

Re: [PATCH v6 10/34] x86, x86/mm, x86/xen, olpc: Use __va() against  just the physical address in cr3 Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2017-06-08 00:10 +0200
  Re: [PATCH v6 10/34] x86, x86/mm, x86/xen, olpc: Use __va() against  just the physical address in cr3 Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2017-06-08 23:00 +0200
    Re: [PATCH v6 10/34] x86, x86/mm, x86/xen, olpc: Use __va() against  just the physical address in cr3 Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2017-06-08 23:20 +0200
      Re: [Xen-devel] [PATCH v6 10/34] x86, x86/mm, x86/xen, olpc: Use  __va() against just the physical address in cr3 Andrew Cooper <andrew.cooper3@citrix.com> - 2017-06-09 00:10 +0200
        Re: [Xen-devel] [PATCH v6 10/34] x86, x86/mm, x86/xen, olpc: Use  __va() against just the physical address in cr3 Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2017-06-09 20:50 +0200
          Re: [Xen-devel] [PATCH v6 10/34] x86, x86/mm, x86/xen, olpc: Use  __va() against just the physical address in cr3 Andrew Cooper <andrew.cooper3@citrix.com> - 2017-06-09 21:00 +0200
          Re: [Xen-devel] [PATCH v6 10/34] x86, x86/mm, x86/xen, olpc: Use  __va() against just the physical address in cr3 Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2017-06-09 21:50 +0200

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