[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Xen-devel] [PATCH v6 0/2] add new p2m type class and new p2m type

Hi Tim & Jan,

  Thank you very much for your review.
And could you please also help me about how to get an ACK? I'm not sure what's the next action I need to take. :-)


On 12/6/2014 11:55 AM, Yu Zhang wrote:
XenGT (Intel Graphics Virtualization technology, please refer to
xengt) driver runs inside Dom0 as a virtual graphics device model,
and needs to trap and emulate the guest's write operations to some
specific memory pages, like memory pages used by guest graphics
driver as PPGTT(per-process graphics translation table). We added
a new p2m type, p2m_mmio_write_dm, to trap and emulate the write
operations on these graphic page tables.

Handling of this new p2m type are similar with existing p2m_ram_ro
in most condition checks, with only difference on final policy of
emulation vs. drop. For p2m_ram_ro types, write operations will not
trigger the device model, and will be discarded later in __hvm_copy();
while for the p2m_mmio_write_dm type pages, writes will go to the
device model via ioreq-server.

Previously, the conclusion in our v3 patch review is to provide a
more generalized HVMOP_map_io_range_to_ioreq_server hypercall, by
seperating rangesets inside a ioreq server to read-protected/write-
protected/both-prtected. Yet, after offline discussion with Paul,
we believe a more simplified solution may suffice. We can keep the
existing HVMOP_map_io_range_to_ioreq_server hypercall, and let the
user decide whether or not a p2m type change is necessary, because
in most cases the emulator will already use the p2m_mmio_dm type.

Changes from v5:
  - Stricter type checks for p2m type transitions;
  - One code style change.

Changes from v4:
  - A new p2m type class, P2M_DISCARD_WRITE_TYPES, is added;
  - A new predicate, p2m_is_discard_write, is used in __hvm_copy()/
    to discard the write operations;
  - The new p2m type, p2m_mmio_write_dm, is added to P2M_RO_TYPES;
  - Coding style changes;

Changes from v3:
  - Use the existing HVMOP_map_io_range_to_ioreq_server hypercall
    to add write protected range;
  - Modify the HVMOP_set_mem_type hypercall to support the new p2m
    type for this range.

Changes from v2:
  - Remove excute attribute of the new p2m type p2m_mmio_write_dm;
  - Use existing rangeset for keeping the write protection page range
    instead of introducing hash table;
  - Some code style fix.

Changes from v1:
  - Changes the new p2m type name from p2m_ram_wp to p2m_mmio_write_dm.
    This means that we treat the pages as a special mmio range instead
    of ram;
  - Move macros to c file since only this file is using them.
  - Address various comments from Jan.

Yu Zhang (2):
   Add a new p2m type class - P2M_DISCARD_WRITE_TYPES
   add a new p2m type - p2m_mmio_write_dm

  xen/arch/x86/hvm/hvm.c          | 25 ++++++++++---------------
  xen/arch/x86/mm/p2m-ept.c       |  1 +
  xen/arch/x86/mm/p2m-pt.c        |  1 +
  xen/arch/x86/mm/shadow/multi.c  |  2 +-
  xen/include/asm-x86/p2m.h       |  9 ++++++++-
  xen/include/public/hvm/hvm_op.h |  1 +
  6 files changed, 22 insertions(+), 17 deletions(-)

Xen-devel mailing list



Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.