Iotlb_Reg-Iotlb Invalidate Register - Intel 2ND GENERATION CORE PROCESSOR FAMILY DESKTOP - DATASHEET VOLUME 2 01-2011 Datasheet

Processor Configuration Registers
2.18.28 IOTLB_REG—IOTLB Invalidate Register
This register invalidates the IOTLB. The act of writing the upper byte of the IOTLB_REG
with IVT bit set causes the hardware to perform the IOTLB invalidation.
B/D/F/Type:
Address Offset:
Reset Value:
Access:
Size:
BIOS Optimal Default
Bit
63
62:62
61:60
59:59
Datasheet, Volume 2
0/0/0/GFXVTBAR
108–10Fh
0200000000000000h
RW-V, RW, RO-V
64 bits
0000000000000h
Reset RST/
Attr
Value PWR
RW-V 0h Uncore
RO 0h
RW 0h Uncore
RO 0h
Description
Invalidate IOTLB (IVT)
Software requests IOTLB invalidation by setting this bit. Software
must also set the requested invalidation granularity by
programming the IIRG field.
Hardware clears the IVT bit 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.
Reserved
IOTLB Invalidation Request Granularity (IIRG)
When requesting hardware to invalidate the IOTLB (by setting the
IVT bit), 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
Reserved
245