Datasheet

Datasheet, Volume 2 249
Processor Configuration Registers
2.18.27 IVA_REG—Invalidate Address Register
This register provides the DMA address whose corresponding IOTLB entry needs to be
invalidated through the corresponding IOTLB Invalidate register. This register is a write
only register.
B/D/F/Type: 0/0/0/GFXVTBAR
Address Offset: 100–107h
Reset Value: 0000_0000_0000_0000h
Access: RW
Size: 64 bits
BIOS Optimal Default 0000_0000h
Bit Attr
Reset
Value
RST/
PWR
Description
63:39 RO 0h Reserved
38:12 RW 0000000h Uncore
Address (ADDR)
Software provides the DMA address that needs to be page-
selectively invalidated. To make a page-selective invalidation
request to hardware, software must first write the appropriate
fields in this register, and then issue the appropriate page-selective
invalidate command through the IOTLB_REG. Hardware ignores
bits 63: N, where N is the maximum guest address width (MGAW)
supported.
11:7 RO 0h Reserved
6 RW 0h Uncore
Invalidation Hint (IH)
This bit provides hint to hardware about preserving or flushing the
non-leaf (page-directory) entries that may be cached in hardware:
0 = Software may have modified both leaf and non-leaf page-
table entries corresponding to mappings specified in the ADDR
and AM fields. On a page-selective invalidation request,
hardware must flush both the cached leaf and non-leaf page-
table entries corresponding to the mappings specified by
ADDR and AM fields.
1 = Software has not modified any non-leaf page-table entries
corresponding to mappings specified in the ADDR and AM
fields. On a page-selective invalidation request, hardware may
preserve the cached non-leaf page-table entries
corresponding to mappings specified by ADDR and AM fields.
5:0 RW 00h Uncore
Address Mask (AM)
The value in this field specifies the number of low-order bits of the
ADDR field that must be masked for the invalidation operation.
This field enables software to request invalidation of contiguous
mappings for size-aligned regions. For example:
Mask ADDR bits Pages
Value masked invalidated
0 None 1
112 2
2 13:12 4
3 14:12 8
4 15:12 16
... ... ...
When invalidating mappings for super-pages, software must
specify the appropriate mask value. For example, when
invalidating mapping for a 2 MB page, software must specify an
address mask value of at least 9.
Hardware implementations report the maximum supported mask
value through the Capability register.