xen/arm: smmuv1: Intelligent SMR allocation

xen/arm: smmuv1: Intelligent SMR allocation

Backport 588888a7399db352d2b1a41c9d5b3bf0fd482390
"iommu/arm-smmu: Intelligent SMR allocation" from the Linux kernel

This patch fix the stream match conflict issue when two devices have the
same stream-id.

Only difference while applying this patch with regard to Linux patch are
as follows:
1. Spinlock is used in place of mutex when attaching a device to the
   SMMU via arm_smmu_master_alloc_smes(..) function call.Replacing the
   mutex with spinlock is fine here as we are configuring the hardware
   via registers and it is very fast.

2. move iommu_group_alloc(..) function call in arm_smmu_add_device(..)
   function from the start of the function to the end.

Original commit message:
    iommu/arm-smmu: Intelligent SMR allocation

    Stream Match Registers are one of the more awkward parts of the SMMUv2
    architecture; there are typically never enough to assign one to each
    stream ID in the system, and configuring them such that a single ID
    matches multiple entries is catastrophically bad - at best, every
    transaction raises a global fault; at worst, they go *somewhere*.

    To address the former issue, we can mask ID bits such that a single
    register may be used to match multiple IDs belonging to the same device
    or group, but doing so also heightens the risk of the latter problem
    (which can be nasty to debug).

    Tackle both problems at once by replacing the simple bitmap allocator
    with something much cleverer. Now that we have convenient in-memory
    representations of the stream mapping table, it becomes straightforward
    to properly validate new SMR entries against the current state, opening
    the door to arbitrary masking and SMR sharing.

    Another feature which falls out of this is that with IDs shared by
    separate devices being automatically accounted for, simply associating a
    group pointer with the S2CR offers appropriate group allocation almost
    for free, so hook that up in the process.

    Signed-off-by: Robin Murphy <robin.murphy@arm.com>
    Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Rahul Singh <rahul.singh@arm.com>
Acked-by: Stefano Stabellini <sstabellini@kernel.org>
Reviewed-by: Bertrand Marquis <bertrand.marquis@arm.com>
Acked-by: Julien GralL <jgrall@amazon.com>