Re: [PATCH v5 0/1] Implements MMIO emulation for lvx/stvx instructions

On Thu, Feb 01, 2018 at 04:15:38PM -0200, Jose Ricardo Ziviani wrote:

v5:
 - Fixed the mask off of the effective address

v4:
  - Changed KVM_MMIO_REG_VMX to 0xc0 because there are 64 VSX registers

v3:
  - Added Reported-by in the commit message

v2:
  - kvmppc_get_vsr_word_offset() moved back to its original place
  - EA AND ~0xF, following ISA.
  - fixed BE/LE cases

TESTS:

For testing purposes I wrote a small program that performs stvx/lvx using the
program's virtual memory and using MMIO. Load/Store into virtual memory is the
model I use to check if MMIO results are correct (because only MMIO is emulated
by KVM).

I'd be interested to see your test program because in my testing it's
still not right, unfortunately.  Interestingly, it is right for the BE
guest on LE host case.  However, with a LE guest on a LE host the two
halves are swapped, both for lvx and stvx:

error in lvx at byte 0
was: -> 62 69 70 77 7e 85 8c 93 2a 31 38 3f 46 4d 54 5b
ref: -> 2a 31 38 3f 46 4d 54 5b 62 69 70 77 7e 85 8c 93
error in stvx at byte 0
was: -> 49 50 57 5e 65 6c 73 7a 11 18 1f 26 2d 34 3b 42
ref: -> 11 18 1f 26 2d 34 3b 42 49 50 57 5e 65 6c 73 7a

The byte order within each 8-byte half is correct but the two halves
are swapped.  ("was" is what was in memory and "ref" is the correct
value.  For lvx it does lvx from emulated MMIO and stvx to ordinary
memory, and for stvx it does lvx from ordinary memory and stvx to
emulated MMIO.  In both cases the checking is done with a byte by byte
comparison.)

Paul.