Re: [Xen-devel] [PATCH V4 1/3] xen/mem_access: Support for memory-content hiding

["Lengyel, Tamas" <tlengyel@xxxxxxxxxxx>]

On Wed, Jul 8, 2015 at 6:22 AM, Razvan Cojocaru <rcojocaru@xxxxxxxxxxxxxxx> wrote:

This patch adds support for memory-content hiding, by modifying the
value returned by emulated instructions that read certain memory
addresses that contain sensitive data. The patch only applies to
cases where MEM_ACCESS_EMULATE or MEM_ACCESS_EMULATE_NOWRITE have
been set to a vm_event response.

Signed-off-by: Razvan Cojocaru <rcojocaru@xxxxxxxxxxxxxxx>
Acked-by: George Dunlap <george.dunlap@xxxxxxxxxxxxx>

---
Changes since V3:
 - Renamed MEM_ACCESS_SET_EMUL_READ_DATA to
   VM_EVENT_FLAG_SET_EMUL_READ_DATA and updated its comment.
 - Removed xfree(v->arch.vm_event.emul_read_data) from
   free_vcpu_struct().
 - Returning X86EMUL_UNHANDLEABLE from hvmemul_cmpxchg() when
   !curr->arch.vm_event.emul_read_data.
 - Replaced in xmalloc_bytes() with xmalloc_array() in
   hvmemul_rep_outs_set_context().
 - Setting the rest of the buffer to zero in hvmemul_rep_movs()
   (no longer leaking heap contents).
 - No longer memset()ing the whole buffer before copy (just zeroing
   out the rest).
 - Moved hvmemul_ctxt->set_context = 0 to hvm_emulate_prepare() and
   removed hvm_emulate_one_set_context().
---
 tools/tests/xen-access/xen-access.c |    2 +-
 xen/arch/x86/hvm/emulate.c          |  138 ++++++++++++++++++++++++++++++++++-
 xen/arch/x86/hvm/event.c            |   50 ++++++-------
 xen/arch/x86/mm/p2m.c               |   92 +++++++++++++----------
 xen/common/domain.c                 |    2 +
 xen/common/vm_event.c               |   23 ++++++
 xen/include/asm-x86/domain.h        |    2 +
 xen/include/asm-x86/hvm/emulate.h   |   10 ++-
 xen/include/public/vm_event.h       |   31 ++++++--
 9 files changed, 274 insertions(+), 76 deletions(-)

Acked-by: Tamas K Lengyel <tlengyel@xxxxxxxxxxx>

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