On 2022/4/13 7:04, Tian, Kevin wrote:
From: Jason Gunthorpe<jgg@xxxxxxxxxx>
Sent: Tuesday, April 12, 2022 9:21 PM
On Tue, Apr 12, 2022 at 09:13:27PM +0800, Lu Baolu wrote:
btw as discussed in last version it is not necessarily to recalculate
snoop control globally with this new approach. Will follow up to
clean it up after this series is merged.
Agreed. But it also requires the enforce_cache_coherency() to be called
only after domain being attached to a device just as VFIO is doing.
that actually makes sense, right? w/o device attached it's pointless to
call that interface on a domain...
Agreed. Return -EOPNOTSUPP or -EINVAL to tell the caller that this
operation is invalid before any device attachment.
That is backwards. enforce_cache_coherency() succeeds on an empty
domain and attach of an incompatible device must fail.
seems it's just a matter of the default policy on an empty domain. No
matter we by default allow enforce_cache_coherency succeed or not
the compatibility check against the default policy must be done anyway
when attaching a device.
given most IOMMUs supports force-snooping, allowing it succeed by
default certainly makes more sense.
Make sense. I will come up with the patches after this series is merged.
Best regards,
baolu
