Processor Configuration Registers
2.18.7
CCMD_REG—Context Command Register
This register manages context cache. The act of writing the uppermost byte of the
CCMD_REG with the ICC field set causes the hardware to perform the context-cache
invalidation.
B/D/F/Type:
Address Offset:
Reset Value:
Access:
0/0/0/GFXVTBAR
28–2Fh
0800000000000000h
RW, RW-V, RO-V
64 bits
Size:
BIOS Optimal Default
000000000h
Reset
Value
RST/
PWR
Bit
Access
Description
Invalidate Context-Cache (ICC)
Software requests invalidation of context-cache by setting this
field. Software must also set the requested invalidation
granularity by programming the CIRG field. Software must read
back and check the ICC field is Clear to confirm the invalidation is
complete. Software must not update this register when this field
is set.
Hardware clears the ICC field to indicate the invalidation request
is complete. Hardware also indicates the granularity at which the
invalidation operation was performed through the CAIG field.
63
RW-V
0h
Uncore
Software must submit a context-cache invalidation request
through this field only when there are no invalidation requests
pending at this remapping hardware unit.
Since information from the context-cache may be used by
hardware to tag IOTLB entries, software must perform domain-
selective (or global) invalidation of IOTLB after the context cache
invalidation has completed.
Hardware implementations reporting write-buffer flushing
requirement (RWBF=1 in Capability register) must implicitly
perform a write buffer flush before invalidating the context
cache.
Context Invalidation Request Granularity (CIRG)
Software provides the requested invalidation granularity through
this field when setting the ICC field:
00 = Reserved.
01 = Global Invalidation request.
10 = Domain-selective invalidation request. The target domain-id
must be specified in the DID field.
11 = Device-selective invalidation request. The target source-
id(s) must be specified through the SID and FM fields, and
the domain-id (that was programmed in the context-entry
for these device(s)) must be provided in the DID field.
62:61
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 ICC field. At this time, hardware also
indicates the granularity at which the actual invalidation was
performed through the CAIG field.
Datasheet, Volume 2
273
INTEL [ INTEL ]
