Hi all, This adds requester IDs to ARM CPUs and adds a "user-defined" memory attribute.
The requester ID on ARM CPUs is there because I've seen some cases where there's an IOMMU between a CPU and memory that uses the CPU's requester ID to look up how it should translate, such as an SMMU TBU or some other IOMMU-like device. For a specific downstream example I've seen, Xilinx overrides CPU attributes with ones passed in by an object property in order to have their IOMMUs work: https://github.com/Xilinx/qemu/blob/23b643ba1683a47ef49447a45643fe2172d6f8ca/accel/tcg/cputlb.c#L1127. The object property with the memory attributes is declared here, for reference: https://github.com/Xilinx/qemu/blob/23b643ba1683a47ef49447a45643fe2172d6f8ca/target/arm/cpu.c#L1310. The user-defined attribute represents optional user signals that are a part of AMBA-AXI. As the name suggests, these are defined per-implementation and devices that receive these have their own interpretation of what the user-defined attribute means. We add them in CPUs and PCI transactions, because some of their attributes are set in functions in ways that are not user-facing. DMAs or other devices that set attributes (using address_space_rw or some other means), can add them on a per-device basis. RFC because it's possible we might want this implementated in some other way, and it touches some pretty frequently used code that I'm somewhat familiar with, but not 100% familiar with. Thanks, Joe Joe Komlodi (5): target/arm: Add requester ID to memattrs memattrs: Fix target_tlb_bit whitespace memattrs: Add user-defined attribute target/arm: Add user-defined memattrs hw/pci: Add user-defined memattrs hw/pci/pci.c | 3 +++ include/exec/memattrs.h | 8 +++++--- include/hw/pci/pci_device.h | 1 + target/arm/cpu.c | 6 ++++++ target/arm/cpu.h | 8 ++++++++ target/arm/ptw.c | 9 +++++++++ 6 files changed, 32 insertions(+), 3 deletions(-) -- 2.44.0.rc0.258.g7320e95886-goog
