[Xen-devel] [PATCH 0/5] Skip unneeded VMENTRY & VMEXIT

[Don Slutz <dslutz@xxxxxxxxxxx>]

Using a new enough QEMU that has:

commit 7665d6ba98e20fb05c420de947c1750fd47e5c07
Author: Paul Durrant <paul.durrant@xxxxxxxxxx>
Date:   Tue Jan 20 11:06:19 2015 +0000

    Xen: Use the ioreq-server API when available
    

means that hvmloader and the guest will do pci config accesses that
will not be sent to QEMU.  However hvm_complete_assist_req() (which
is the routine that does the work) returns a 1 which
hvm_send_assist_req() returns to the caller which means that the
request was sent to QEMU and need to be waited for.

This is not the case.  hvm_complete_assist_req() has called on
hvm_io_assist() which has changed the io_state from
HVMIO_awaiting_completion to HVMIO_completed if needed.  But
hvmemul_do_io() thinks that it needs to wait on the IOREQ_READ case,
and returns X86EMUL_RETRY.

[PATCH 1/5] DEBUG: xentrace: Add debug of HANDLE_PIO
  -- No need to apply

[PATCH 2/5] xentrace: Adjust IOPORT & MMIO format
  -- Simple bugfix.  xentrace_format is not converting these correctly

[PATCH 3/5] hvmemul_do_io: If the send to the ioreq server failed do
  -- Simple bugfix.  Do the same thing as when hvm_has_dm() returns
     a zero.

[PATCH 4/5] hvm_complete_assist_req: We should not be able to get
  -- This ASSERT was sugested by Paul Durrant.  Since I was in the
     file, just add it.

[PATCH 5/5] hvm_complete_assist_req: Tell caller we failed to send
  -- The real fix.  Does depend on [PATCH 3/5] hvmemul_do_io: If the send ...



Here is the before xentrace output using the "[PATCH 1/5] DEBUG:
xentrace: Add debug of HANDLE_PIO" (which I do not expect to be
applied.  It is first because that is the order you need to use to
reproduce the xentrace output):


CPU0  685992932190 (+    2292)  VMEXIT      [ exitcode = 0x0000001e, rIP  = 
0x00101581 ]
CPU0  0 (+       0)  HANDLE_PIO [ port = 0x0cfe size = 2 dir = 1 io_state = 5 
ret = 0 ]
CPU0  685992934938 (+    2748)  vlapic_accept_pic_intr [ i8259_target = 1, 
accept_pic_int = 1 ]
CPU0  685992935526 (+     588)  VMENTRY
CPU0  685992937650 (+    2124)  VMEXIT      [ exitcode = 0x0000001e, rIP  = 
0x00101581 ]
CPU0  0 (+       0)  IOPORT_READ [ port = 0x0cfe, data = 0x00000000 ]
CPU0  0 (+       0)  HANDLE_PIO [ port = 0x0cfe size = 2 dir = 1 io_state = 0 
ret = 1 ]
CPU0  685992940248 (+    2598)  vlapic_accept_pic_intr [ i8259_target = 1, 
accept_pic_int = 1 ]
CPU0  685992940968 (+     720)  VMENTRY


And after:


CPU2  1028654638584 (+    2388)  VMEXIT      [ exitcode = 0x0000001e, rIP  = 
0x00101581 ]
CPU2  0 (+       0)  IOPORT_READ [ port = 0x0cfe, data = 0xffffffff ]
CPU2  0 (+       0)  HANDLE_PIO [ port = 0x0cfe size = 2 dir = 1 io_state = 0 
ret = 1 ]
CPU2  1028654641932 (+    3348)  vlapic_accept_pic_intr [ i8259_target = 1, 
accept_pic_int = 1 ]
CPU2  1028654642586 (+     654)  VMENTRY


Don Slutz (5):
  DEBUG: xentrace: Add debug of HANDLE_PIO
  xentrace: Adjust IOPORT & MMIO format
  hvmemul_do_io: If the send to the ioreq server failed do not retry.
  hvm_complete_assist_req: We should not be able to get here on
    IOREQ_TYPE_PCI_CONFIG
  hvm_complete_assist_req: Tell caller we failed to send

 tools/xentrace/formats          | 10 ++++++----
 xen/arch/x86/hvm/emulate.c      |  4 ++++
 xen/arch/x86/hvm/hvm.c          |  3 ++-
 xen/arch/x86/hvm/io.c           |  4 ++++
 xen/include/asm-x86/hvm/trace.h |  2 +-
 xen/include/public/trace.h      |  2 ++
 6 files changed, 19 insertions(+), 6 deletions(-)

-- 
1.8.4


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel