iommu/arm-smmu-v3: Seize private ASID

hulk inclusion
category: feature
bugzilla: 14369
CVE: NA
-------------------

The SMMU has a single ASID space, the union of shared and private ASID
sets. This means that the context table module competes with the arch
allocator for ASIDs. Shared ASIDs are those of Linux processes, allocated
by the arch, and contribute in broadcast TLB maintenance. Private ASIDs
are allocated by the SMMU driver and used for "classic" map/unmap DMA.
They require explicit TLB invalidations.

When we pin down an mm_context and get an ASID that is already in use by
the SMMU, it belongs to a private context. We used to simply abort the
bind, but this is unfair to users that would be unable to bind a few
seemingly random processes. Try to allocate a new private ASID for the
context in use, and make the old ASID shared.

Introduce a new lock to prevent races when rewriting context descriptors.

Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
Signed-off-by: Fang Lijun <fanglijun3@huawei.com>
Reviewed-by: Hanjun Guo <guohanjun@huawei.com>
Reviewed-by: Zhen Lei <thunder.leizhen@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>