MdeModulePkg/AhciPei: Limit max transfer blocknum for 48-bit address

REF:https://bugzilla.tianocore.org/show_bug.cgi?id=1483

Due to the limited resource on the VTd DMA buffer size in the PEI phase,
the driver will limit the maximum transfer block number for 48-bit
addressing.

According to PCDs:
gIntelSiliconPkgTokenSpaceGuid.PcdVTdPeiDmaBufferSize|0x00400000
gIntelSiliconPkgTokenSpaceGuid.PcdVTdPeiDmaBufferSizeS3|0x00200000

The default buffer size allocated for IOMMU mapping is:
* 4M bytes for non-S3 cases;
* 2M bytes for S3

For ATA devices in 48-bit address mode, the maximum block number is
currently set to 0xFFFF. For a device with block size equal to 512 bytes,
the maximum buffer allowed for mapping within AhciPei driver will be close
to 32M bytes. Thus, this commit will limit the 48-bit mode maximum block
number to 0x800, which means 1M-byte maximum buffer for mapping when the
block size of a device is 512 bytes. By doing so, potential failure on
calls to the IOMMU 'Map' service can be avoided.

Cc: Eric Dong <eric.dong@intel.com>
Cc: Jian J Wang <jian.j.wang@intel.com>
Signed-off-by: Hao Wu <hao.a.wu@intel.com>
Reviewed-by: Ray Ni <ray.ni@intel.com>

0 files changed, 0 insertions, 0 deletions