Each VCPU has its own root page table, but all VCPUs are sharing the
same one with EPT (or AMD nested paging for that matter).
Tom Birch wrote:
Cool, thanks, that's what I thought. Is there any reason the EPT is a
per-VCPU data structure? Could you please point me to the bits of code
that do this sharing? I'm getting lost looking at all the assignments
to the pShwPageCR3* variables, they still all seem to be per-VCPU, I
can't find where it hooks into the root VM structure.
cheers,
Tom
On Thu, Oct 29, 2009 at 1:19 PM, Sander van Leeuwen
<[email protected]> wrote:
The EPT structures are shared between all VCPUs as they contain a guest
physical to host physical mapping, which
is independent of the VCPU. The host OS is irrelevant.
Tom Birch wrote:
I'm looking through the page management code, specifically hardware
acceleration on Intel with EPT, and I can't quite figure out the
high-level relationships between various structures. Both the VMCS and
EPTP seem to be per-PVMCPU data structures, does this mean that within
a single VM, you can have multiple distinct EPTPs (on different
VCpus), or is this arrangement just a consequence of the way shadow
paging worked before EPT? Put another way, can I guarantee that all
VCpus within a single VM will all share the same EPTP? I'm mainly
concerned about how this applies to Darwin if that matters, but I
seems like a fairly Host-OS-agnostic feature.
cheers,
Tom
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Kind regards / Mit freundlichen Gruessen / Met vriendelijke groet
--
Sun Microsystems GmbH Sander van Leeuwen
Werkstrasse 24 Senior Staff Engineer, VirtualBox
71384 Weinstadt, Germany mailto:[email protected]
================================================
Sitz der Gesellschaft: Sun Microsystems GmbH,
Sonnenallee 1, 85551 Kirchheim-Heimstetten
Amtsgericht Muenchen: HRB 161028
Geschaeftsfuehrer: Thomas Schroeder,
Wolfgang Engels, Dr. Roland Boehmer
Vorsitzender des Aufsichtsrates: Martin Haering
================================================
--
Kind regards / Mit freundlichen Gruessen / Met vriendelijke groet
--
Sun Microsystems GmbH Sander van Leeuwen
Werkstrasse 24 Senior Staff Engineer, VirtualBox
71384 Weinstadt, Germany mailto:[email protected]
================================================
Sitz der Gesellschaft: Sun Microsystems GmbH,
Sonnenallee 1, 85551 Kirchheim-Heimstetten
Amtsgericht Muenchen: HRB 161028
Geschaeftsfuehrer: Thomas Schroeder,
Wolfgang Engels, Dr. Roland Boehmer
Vorsitzender des Aufsichtsrates: Martin Haering
================================================
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