Datasheet, Volume 2
289
Processor Configuration Registers
2.21.29 IOTLB_REG—IOTLB Invalidate Register
Register to invalidate IOTLB. The act of writing the upper byte of the IOTLB_REG with
IVT field Set causes the hardware to perform the IOTLB invalidation.
B/D/F/Type:
0/0/0/VC0PREMAP
Address Offset:
108–10Fh
Reset Value:
0000000000000000h
Access:
RW, RO-V, RW-V
Size:
64 bits
BIOS Optimal Default
0000000000000h
Bit
Attr
Reset
Value
RST/
PWR
Description
63
RW-V
0h
Uncore
Invalidate IOTLB (IVT)
Software requests IOTLB invalidation by setting this field. Software
must also set the requested invalidation granularity by
programming the IIRG field.
Hardware clears the IVT field to indicate the invalidation request is
complete. Hardware also indicates the granularity at which the
invalidation operation was performed through the IAIG field.
Software must not submit another invalidation request through
this register while the IVT field is set, nor update the associated
Invalidate Address register.
Software must not submit IOTLB invalidation requests when there
is a context-cache invalidation request pending at this remapping
hardware unit.
Hardware implementations reporting write-buffer flushing
requirement (RWBF=1 in Capability register) must implicitly
perform a write buffer flushing before invalidating the IOTLB.
62:62
RO
0h
Reserved
61:60
RW
0h
Uncore
IOTLB Invalidation Request Granularity (IIRG)
When requesting hardware to invalidate the IOTLB (by setting the
IVT field), software writes the requested invalidation granularity
through this field. The following are the encodings for the field.
00 = Reserved.
01 = Global invalidation request.
10 = Domain-selective invalidation request. The target domain-id
must be specified in the DID field.
11 = Page-selective invalidation request. The target address,
mask and invalidation hint must be specified in the
Invalidate Address register, and the domain-id must be
provided in the DID field.
Hardware implementations may process an invalidation request by
performing invalidation at a coarser granularity than requested.
Hardware indicates completion of the invalidation request by
clearing the IVT field. At this time, the granularity at which actual
invalidation was performed is reported through the IAIG field.
59:59
RO
0h
Reserved