On Mon, Aug 31, 2026 at 09:23:31PM +0800, Chen Pei wrote: > This series adds CXL support to the RISC-V virt machine, following the > approach used by the ARM virt machine: CXL host bridges (pxb-cxl) are > described as ACPI0016 devices, an ACPI0017 (CXLM) device is added to the > DSDT with a _DEP on the CXL host bridges, and a CEDT table is built. A > bios-tables test is added to pin down the generated ACPI tables.
I am guessing this will be merged by riscv maintainers? acpi things Acked-by: Michael S. Tsirkin <[email protected]> > Changes since v4 > ---------------- > - tests/qtest: DSDT.cxl regenerated against the in-tree > edk2-riscv-code.fd blob that the test boots (Junjie): the v4 golden > carried the window allocation of my local edk2-stable202602 build. > The 64-bit window is now 0x400100000..0x40010FFFF with the matching > PCI0 range shift; the AML fragment in the commit message is updated > accordingly. CEDT.cxl is unchanged. > - hw/riscv/virt: pci_bus_add_fw_cfg_extra_pci_roots() moved out of > the cxl block (Junjie), so plain pxb-pcie expander bridges are also > advertised to firmware with cxl=off, in line with arm/virt, pc and > hppa. > - Collected review tags. > > Changes since v3 > ---------------- > - The CXL host bridge resource handling is reworked, following Junjie > Cao's suggestion (and Igor Mammedov's earlier "fix UEFI" direction): > instead of reserving a fixed 256 MiB carve-out and simulating the > firmware PCI initialization in QEMU, the machine now advertises the > pxb-cxl expander root buses to firmware via the etc/extra-pci-roots > fw_cfg file (pci_bus_add_fw_cfg_extra_pci_roots(), as arm/virt and > x86 do). EDK2's PciBusDxe then enumerates behind the CXL host > bridge and assigns the root-port window and bus numbers, and > build_crs() emits a correct _CRS for the ACPI0016 host bridge. > This keeps the machine code minimal (a single call, no carve-out), > scales to multiple pxb-cxl host bridges, and lets firmware size the > window to what is actually behind the bridge. > - The bios-tables test is split into the staged flow documented in > bios-tables-test.c, and ordered the same way the riscv64 goldens were > originally added upstream (Sunil V L's commit cc3ba2422554 et al.): > the feature code comes first, then three consecutive commits -- empty > golden files + allowed-diff.h, the test code, and the populated golden > master binaries with an emptied allowed-diff.h. > > Changes since v2 > ---------------- > - hw/riscv/virt: The MMIO-window patch no longer touches the common > gpex code (Igor). The gpex_cfg.cxl_mmio32 field and the is_cxl > static _CRS branch are dropped; the ACPI0016 _CRS now comes from the > generic build_crs() path. Since EDK2 does not enumerate the pxb-cxl > expander bridge, riscv simulates the firmware PCI initialization > (reserved window + depth-first bridge bus numbers) and re-applies it > via a reset handler. > - hw/riscv/virt: Drops the machine-global window/bus-range synthesis > that did not scale past one pxb-cxl (Junjie). The series targets a > single CXL host bridge for now, documented in the commit message and > a TODO. > - hw/riscv/virt: CXL host register region and FMW setup folded into a > single cxl_host_state_init() helper; redundant braces removed in > create_fdt_pcie() (Daniel). > - hw/riscv/virt-acpi-build: the _DEP commit message documents the > kernel-compatibility behaviour (Alistair). > - Carried review tags: Sunil V L's Reviewed-by on the _DEP patch and > Alistair Francis's Acked-by on the test. > > Changes since v1 > ---------------- > - hw/riscv/virt: PCIBus *bus renamed to PCIBus *pci_bus (Jonathan). > - hw/riscv/virt: Dropped outer if (s->pci_bus) guard around > cxl_hook_up_pxb_registers(); the function already handles a NULL > bus internally (Jonathan). > - hw/riscv/virt-acpi-build: All s->bus references updated to > s->pci_bus; iasl -d decompiled DSDT fragment added to commit > message. > - hw/riscv/virt,gpex: Commit message expanded with PCI-to-PCI Bridge > Spec ยง3.2.5.8/9/10 citations (Jonathan). > - Original patch 4 ("Map committed HDM decoder ranges as RAM for > direct DMA") dropped; superseded by Alireza Sanaee's v8 series [1], > which is now merged upstream and thus no longer a prerequisite. > - New patch 4: RISC-V ACPI bios-tables test for CXL, with golden AML > files generated and included. > > [1] > https://lore.kernel.org/qemu-devel/[email protected]/ > > Test > ---- > Built riscv64-softmmu and ran the new bios-tables test together with the > existing riscv64 ACPI tests; all pass. > > Also booted an RVA22 guest with EDK2 firmware, using pxb-cxl + cxl-rp + > cxl-type3 + a CFMW: EDK2's PciBusDxe enumerates behind the CXL host > bridge (advertised via etc/extra-pci-roots), the root port and Type3 > device show up (0000:0c:00.0 / 0000:0d:00.0), and 'cxl list' reports > the memdev (4 GiB) and the CFMWS root decoder. > > QEMU invocation (CXL-relevant options shown): > > qemu-system-riscv64 \ > -M virt,aia=aplic-imsic,acpi=on,cxl=on \ > -cpu rva22s64 -smp 2 -m 4G \ > -object memory-backend-ram,id=vmem0,share=on,size=4G \ > -device pxb-cxl,bus_nr=12,bus=pcie.0,id=cxl.1 \ > -device cxl-rp,port=0,bus=cxl.1,id=rp0,chassis=0,slot=2 \ > -device cxl-type3,bus=rp0,volatile-memdev=vmem0 \ > -M cxl-fmw.0.targets.0=cxl.1,cxl-fmw.0.size=4G \ > ... > > Verification (total system memory grows by 4 GiB after onlining): > > # cxl list > # cxl enable-memdev mem0 > # cxl create-region -m -t ram -d decoder0.0 -w 1 mem0 -s 4G > # daxctl online-memory dax0.0 > # free -h > > Chen Pei (6): > hw/riscv/virt: Add CXL support to the RISC-V virt machine > hw/riscv/virt-acpi-build: Add _DEP to ACPI0017 for CXL host bridge > dependency > hw/riscv/virt: Advertise the CXL host bridge to firmware via > extra-pci-roots > tests/qtest: Prepare golden files for the RISC-V CXL ACPI test > tests/qtest: Add RISC-V ACPI bios tables test for CXL > tests/qtest: Update RISC-V CXL ACPI golden master binaries > > hw/riscv/Kconfig | 2 + > hw/riscv/virt-acpi-build.c | 52 +++++++++++++++++++++++++ > hw/riscv/virt.c | 46 ++++++++++++++++++++++ > include/hw/riscv/virt.h | 3 ++ > tests/data/acpi/riscv64/virt/CEDT.cxl | Bin 0 -> 108 bytes > tests/data/acpi/riscv64/virt/DSDT.cxl | Bin 0 -> 6331 bytes > tests/qtest/bios-tables-test.c | 54 ++++++++++++++++++++++++++ > 7 files changed, 157 insertions(+) > create mode 100644 tests/data/acpi/riscv64/virt/CEDT.cxl > create mode 100644 tests/data/acpi/riscv64/virt/DSDT.cxl > > -- > 2.50.1
