Processor Configuration Registers
2.18.29 IOTLB_REG—IOTLB Invalidate Register
This register invalidates 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:
Address Offset:
Reset Value:
Access:
0/0/0/GFXVTBAR
108–10Fh
0200000000000000h
RO-V, RW, RW-V
64 bits
Size:
BIOS Optimal Default
0000000000000h
Reset
Value
RST/
PWR
Bit
Access
Description
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.
63
RW-V
0h
Uncore
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 (RSVD)
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.
61:60
RW
0h
Uncore
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 (RSVD)
Datasheet, Volume 2
291
INTEL [ INTEL ]
