v1 -> v2: - provide CXL exclusive MMIO32 & MMIO64 space - hard coded two cxl root ports
RFC because - Many contents are ported from Jonathan' patch on qemu virt design
- Less experience and not particularly confident in sbsa-ref address space design so this might be stupidly broken in a way I've not considered.
Currently the base CXL support for arm platforms is only on Jonathan's patches[1] which have not yet merged into upstream. SBSA-REF can be more like a real machine, thus the support of cxl could be meaningful.
This series leverages Jonathan's patches[1] to design [SBSA_CXL_HOST] and [SBSA_CXL_FIXED_WINDOW] spaces for sbsa-ref layout.
For [SBSA_CXL_HOST], since this creates a default pxb-cxl (bus_nr=0xc0) bridge with two cxl root ports on sbsa-ref, the new memory layout places 64K space for one hard coded cxl host bridge register regions in the sbsa-ref memmap.
According to above design, for now only two cxl type3 devices could be added on the cxl host.
With the 'create_pxb_cxl', users don't need to input '-device pxb-cxl' and '-device cxl-rp' parameters.
In addition, this support indepentent mmio32(32M) & mmio64(1M) space which are enough for cxl components, because in this way the previous pcie mmio32/64 space would not be divided and affected.
However, with the pxb-cxl-host, any cxl root ports and cxl endpoint devices would occupy the BDF number of the original pcie domain. Hence, the max available pcie devices on sbsa-ref would decrease, which seems to bring a series of trouble. I'm looking for some comments on the problems and suggestions on if there are better ways to do it.
For [SBSA_CXL_FIXED_WINDOW], in order to provide CFMWs on sbsa-ref, this extends 1TB space from the hole above RAM Memory [SBSA_MEM] for CXL Fixed Memory Window. 0xA0000000000 is chosen as the base address of this space because of 3 reasons:
1) It is more suitable to choose a static address instead of that implementation in virt, since a dynamic address space layout of sbsa-ref is not appropriate for its original purpose as a reference platform.
2) The Hotplug Memory address range should in the range of maximum addressable range of sbsa-ref platform(0x10000000000-0x80ffffffffff). It is satisfied the requirements of memory hotplug in linux kernel.
3) The start pfn of CFMW should exceed the reserved_pfn_range for onlined numa node.
Based on 'cxl_fmws_link_targets', this adds a new function 'sbsa_cxl_fmws_link_targets' for binding cfmws.target with the default pxb-cxl-bus on sbsa-ref.
In addition, this also adds 'create_cxl_fixed_window_region' to support creating a static cfmw region on sbsa-ref, so users don't need to input '-M cxl-fmw' parameter.
Thus, to run sbsa-ref with a cxl device could use: qemu-system-aarch64 \ -object memory-backend-file,id=mem2,mem-path=/tmp/mem2,size=256M,share=true \ -device cxl-type3,bus=cxl.0,volatile-memdev=mem2,id=cxl-mem1 \
By the way, since the matched firmware correspond to this patch would allocate pcie bus 0xc0 ~ 0xff to pxb-cxl-host, we should add "bus=pcie.0" when we want to plug some devices on the original pcie bus, for example: -device qemu-xhci,bus=pcie.0 \ or -device nvme,serial=deadbeef,bus=pcie.0,drive=hdd \ -drive file=../disk/hdd.qcow2,format=qcow2,id=hdd,if=none \
This series patches are here to hopefully some comments to guide me!
Link: [1]: https://lore.kernel.org/linux-cxl/20220616141950.23374-1-Jonathan.Cameron@hu... [2]: https://edk2.groups.io/g/devel/topic/rfc_edk2_patch_v3_0_1/109403423# [3]: https://edk2.groups.io/g/devel/topic/rfc_patch_edk2_platforms_v2/109403456
Yuquan Wang (1): hw/arm/sbsa-ref: Support CXL Host Bridge & CFMW
docs/system/arm/sbsa.rst | 4 ++ hw/arm/sbsa-ref.c | 122 +++++++++++++++++++++++++++++++++++++- hw/cxl/cxl-host-stubs.c | 2 + hw/cxl/cxl-host.c | 2 +- include/hw/cxl/cxl_host.h | 2 + 5 files changed, 130 insertions(+), 2 deletions(-)