Re: [PATCH 1/2] MdePkg/BaseIoLibIntrinsic: fix SEV (=unrolled) variants of IoWriteFifoXX()

[Brijesh Singh <brijesh.singh@amd.com>]

On 09/04/2017 10:57 AM, Laszlo Ersek wrote:
> In commit b6d11d7c4678 ("MdePkg: BaseIoLibIntrinsic (IoLib class)
> library", 2017-04-12), the MOV instructions in the write loops were
> probably copied from the read loops. However, the operand order was not
> adjusted.
> 
> As a result, the IoWriteFifoXX() routines, when invoked in SEV guests, now
> overwrite the source buffer with value 0x01 / 0x0001 / 0x00000001 -- the
> SevNoRepIo() function returns value 1 in EAX, in SEV guests --, and write
> the same value to the target IO port.
> 
> Fix this by putting the target operand (AL / AX / EAX) first, and the
> source operand (BYTE / WORD / DWORD [ESI/RSI]) second.
> 
> Cc: Brijesh Singh <brijesh.singh@amd.com>
> Cc: Jordan Justen <jordan.l.justen@intel.com>
> Cc: Liming Gao <liming.gao@intel.com>
> Cc: Michael D Kinney <michael.d.kinney@intel.com>
> Fixes: b6d11d7c467810ea7f2e2eda46ef0bdc57bf1475
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Laszlo Ersek <lersek@redhat.com>


Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>