February 2026 - Devel - libvirt List Archives

[RFC PATCH v4 0/7] riscv: add initial sdext support
by Chao Liu 03 Feb '26

03 Feb '26

Hi, Per Daniel's review feedback, this v4 series is based on Alistair's riscv-to-apply.next branch [3]. It depends on patches 1-5 of Max Chou's "Add Zvfbfa extension support" v2 series (not included; apply them first) [2]. It is based on RISC-V Debug Specification 1.0 [1]. It introduces the sdext/sdtrig config bits, DCSR/DPC/DSCRATCH state, Debug Mode enter/leave helpers, DRET, EBREAK entry, single-step, and trigger action=debug mode. To reduce review load, this series focuses on the Sdext features first. The Debug Module (DM) and related flows will follow in a later series. Changes in v4: - Fixed linux-user build errors: moved debug_mode/dcsr/dpc/dscratch fields inside #ifndef CONFIG_USER_ONLY block in cpu.h, and wrapped all code using these fields with proper guards. (Daniel) - Updated dependency from single patch (patch 5 only) to patches 1-5 of Max Chou's "Add Zvfbfa extension support" v2 series to avoid compilation errors. Changes in v3: - Rebase onto Alistair's riscv-to-apply.next branch. - Depend on Max Chou's patch "target/riscv: Use the tb->cs_bqse as the extend tb flags." (not included; apply it first) [2]. - Patch 2: default sdext to false in riscv_cpu_extensions[]. Changes in v2: - Drop the RHCT expected AML update from this series. - Replace the split sdext/sdtrig config bits patch with deprecating the 'debug' CPU property. - Rebase and update patch subjects to target/riscv prefix. Changes in v1: - Debug Mode entry/exit updates DCSR/DPC and restores execution via DRET. - EBREAK honors DCSR ebreak bits and enters Debug Mode when enabled. - Single-step uses DCSR.STEP with a TB flag and a helper at TB exit. It references Max Chou's patch "target/riscv: Use the tb->cs_bqse as the extend tb flags." [2]. - Sdtrig supports action=debug mode for mcontrol/mcontrol6 and reports inst-count triggers in tinfo. Differences vs Debug Spec (known gaps): - No Debug Module (no DMI, dmcontrol/dmstatus, haltreq/resumereq). - No debug ROM, program buffer, abstract commands, or SBA. - Resume is modeled by leaving Debug Mode at cpu_exec_enter. - Step/exception ordering is simplified: if the stepped instruction traps, the normal exception is taken and Debug Mode is not forced. - Several DCSR fields are not fully modeled (stopcount/stoptime, etc). Roadmap (next stage, DM focus): 1) Add a DM core with DMI access and hart state tracking. 2) Implement halt/resume handshake and move Debug Mode transitions under DM control. 3) Add debug ROM, program buffer, and abstract commands for GPR/CSR and memory access. 4) Add SBA if required by tooling. 5) Tighten ordering rules for step/exception/trigger priorities. References: [1] https://github.com/riscv/riscv-debug-spec/releases/tag/1.0 [2] https://lore.kernel.org/qemu-devel/20260108132631.9429-1-max.chou@sifive.co… [3] https://github.com/alistair23/qemu/tree/riscv-to-apply.next Thanks, Chao Chao Liu (6): target/riscv: add sdext debug CSRs state target/riscv: add sdext Debug Mode helpers target/riscv: add dret instruction target/riscv: add sdext enter Debug Mode on ebreak target/riscv: add sdext single-step support target/riscv: add sdtrig trigger action=debug mode Daniel Henrique Barboza (1): target/riscv: deprecate 'debug' CPU property docs/about/deprecated.rst | 7 + include/exec/translation-block.h | 4 +- target/riscv/cpu.c | 62 ++++++++- target/riscv/cpu.h | 9 ++ target/riscv/cpu_bits.h | 33 +++++ target/riscv/cpu_cfg_fields.h.inc | 3 +- target/riscv/cpu_helper.c | 90 ++++++++++++ target/riscv/csr.c | 128 +++++++++++++++++- target/riscv/debug.c | 58 +++++++- target/riscv/helper.h | 3 + target/riscv/insn32.decode | 1 + .../riscv/insn_trans/trans_privileged.c.inc | 24 ++++ target/riscv/machine.c | 44 ++++-- target/riscv/op_helper.c | 70 ++++++++++ target/riscv/tcg/tcg-cpu.c | 21 ++- target/riscv/translate.c | 16 ++- 16 files changed, 548 insertions(+), 25 deletions(-) -- 2.52.0

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Qemu pause-before-switchover and libvirt live migration
by Rogério Vinhal Nunes 02 Feb '26

02 Feb '26

Hello, I’m looking into the libvirt hooks that are available to make use of during a live migration, but there's only hooks on migration begin and migration end. On qemu directly I’m able to use pause-before-switchover migration capability to run a custom operation just before it moves to the destination, but within libvirt it seems that while this is leveraged internally, it’s not currently exposed to the client in a way I can use. Does anyone have any suggestions on how I could expose this to the client in a generic and sensible way? Thanks, Rogerio

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[PATCH v6 0/7] qemu: Implement support for iommufd
by Nathan Chen 02 Feb '26

02 Feb '26

Hi, This is a follow up to the fifth patch series [0] for using iommufd to propagate DMA mappings to the kernel for VM-assigned host devices in a qemu VM. We add a new 'iommufd' attribute for hostdev devices to be associated with the iommufd object. For instance, specifying the iommufd object and associated hostdev in a VM definition: <devices> ... <hostdev mode='subsystem' type='pci' managed='no'> <driver iommufd='yes'/> <source> <address domain='0x0009' bus='0x01' slot='0x00' function='0x0'/> </source> <address type='pci' domain='0x0000' bus='0x15' slot='0x00' function='0x0'/> </hostdev> <hostdev mode='subsystem' type='pci' managed='no'> <driver iommufd='yes'/> <source> <address domain='0x0019' bus='0x01' slot='0x00' function='0x0'/> </source> <address type='pci' domain='0x0000' bus='0x16' slot='0x00' function='0x0'/> </hostdev> ... </devices> This would get translated to a qemu command line with the arguments below. Note that libvirt will open the /dev/iommu and VFIO cdev, passing the associated fd number to qemu: -object '{"qom-type":"iommufd","id":"iommufd0","fd":"24"}' \ -device '{"driver":"vfio-pci","host":"0009:01:00.0","id":"hostdev0","iommufd":"iommufd0","fd":"22","bus":"pci.21","addr":"0x0"}' \ -device '{"driver":"vfio-pci","host":"0019:01:00.0","id":"hostdev1","iommufd":"iommufd0","fd":"25","bus":"pci.22","addr":"0x0"}' \ Changes from v5: - Updated documentation to point to 12.1.0 (QEMU and KVM only) - Move define and VIR_LOG_INIT out of #ifdef __linux__ block in viriommufd.h - Remove unneeded virPCIDeviceFree() from AppArmorSetSecurityHostdevLabel - Always error out if per-process accounting failed Changes from v4: - Move qemuProcessOpenVfioFds() to qemu_process.h in patch 4/7 - Add `linux/iommufd.h` into headers list in the meson.build file - Correct viriommufd.c pre-processor definition indentations - Restore call to virIOMMUFDSetRLimitMode() in patch 5/7 - Fix indentations for various print function calls - Move the qemuProcessOpenVfioFds() call to qemuProcessPrepareHost() - Make qemuProcessOpenVfioFds() static - Remove unnecessary formatting and comment in virPCIDeviceGetVfioPath() - Clean up namespace and cgroup changes with conditional check for iommufd - Remove virIOMMUFDSupported() - Fix seclabel return logic - In Apparmor seclabel logic, use g_autoptr for virPCIDevice pointer Changes from v3: - Resolved issue from v2 where stale FD from previous VM boot was in use - Remove second approach for retrieving VFIO device path in virPCIDeviceGetVfioPath() - Resolve broken build of libvirt on non-Linux platforms - Conditionally define iommufd headers and use system headers where possible - Add non-fatal handling + warning print for EPERM for the IOMMU_OPTION_RLIMIT_MODE ioctl - Replace references to /dev/iommu with VIR_IOMMU_DEV_PATH - Implement virIOMMUFDSupported(void) to check for existence of /dev/iommu on host - Include tests for multiple hostdevs Changes from v2: - Set per-process memory accounting mode for iommufd - Separated out formatting of iommufd object from qemuBuildHostdevCommandLine - Placed hostdev private data implementation in a separate commit - Allocate hostdev private data unconditionally - Compare FDs against -1 - Integrated callback function in virQEMUDriverPrivateDataCallbacks for qemuDomainHostdevPrivateNew - Dropped qemuProcessCloseVfioFds - Addressed other feedback from v2 (formatting, includes, etc.) - Revised seclabel logic to be device-specific for AppArmor and to allow paths for SELinux/DAC This series is on Github: https://github.com/NathanChenNVIDIA/libvirt/commits/iommufd-v6-01-26 Thanks, Nathan [0] https://lists.libvirt.org/archives/list/devel@lists.libvirt.org/thread/GKSD… Nathan Chen (7): qemu: Implement support for associating iommufd to hostdev qemu: Introduce privateData for hostdevs qemu: Support per-process memory accounting for iommufd qemu: open VFIO FDs from libvirt backend qemu: open iommufd FD from libvirt backend qemu: Update Cgroup, namespace, and seclabel for iommufd tests: qemuxmlconfdata: provide iommufd sample XML and CLI args docs/formatdomain.rst | 6 + meson.build | 1 + po/POTFILES | 1 + src/bhyve/bhyve_parse_command.c | 2 +- src/conf/device_conf.c | 11 ++ src/conf/device_conf.h | 1 + src/conf/domain_conf.c | 13 +- src/conf/domain_conf.h | 5 +- src/conf/schemas/basictypes.rng | 5 + src/libvirt_private.syms | 4 + src/libxl/xen_common.c | 2 +- src/libxl/xen_xl.c | 2 +- src/lxc/lxc_native.c | 2 +- src/qemu/qemu_cgroup.c | 3 + src/qemu/qemu_command.c | 76 +++++++++++ src/qemu/qemu_domain.c | 41 ++++++ src/qemu/qemu_domain.h | 17 +++ src/qemu/qemu_namespace.c | 3 + src/qemu/qemu_process.c | 121 ++++++++++++++++++ src/security/security_apparmor.c | 28 ++-- src/security/security_dac.c | 49 +++++-- src/security/security_selinux.c | 47 +++++-- src/security/virt-aa-helper.c | 33 ++++- src/util/meson.build | 1 + src/util/viriommufd.c | 111 ++++++++++++++++ src/util/viriommufd.h | 25 ++++ src/util/virpci.c | 39 ++++++ src/util/virpci.h | 2 + src/vbox/vbox_common.c | 2 +- .../iommufd-q35.x86_64-latest.args | 41 ++++++ .../iommufd-q35.x86_64-latest.xml | 60 +++++++++ tests/qemuxmlconfdata/iommufd-q35.xml | 38 ++++++ ...fd-virt-pci-bus-single.aarch64-latest.args | 32 +++++ ...ufd-virt-pci-bus-single.aarch64-latest.xml | 31 +++++ .../iommufd-virt-pci-bus-single.xml | 22 ++++ .../iommufd-virt.aarch64-latest.args | 36 ++++++ .../iommufd-virt.aarch64-latest.xml | 53 ++++++++ tests/qemuxmlconfdata/iommufd-virt.xml | 29 +++++ .../iommufd.x86_64-latest.args | 35 +++++ .../qemuxmlconfdata/iommufd.x86_64-latest.xml | 38 ++++++ tests/qemuxmlconfdata/iommufd.xml | 30 +++++ tests/qemuxmlconftest.c | 34 +++++ tests/virhostdevtest.c | 2 +- 43 files changed, 1090 insertions(+), 44 deletions(-) create mode 100644 src/util/viriommufd.c create mode 100644 src/util/viriommufd.h create mode 100644 tests/qemuxmlconfdata/iommufd-q35.x86_64-latest.args create mode 100644 tests/qemuxmlconfdata/iommufd-q35.x86_64-latest.xml create mode 100644 tests/qemuxmlconfdata/iommufd-q35.xml create mode 100644 tests/qemuxmlconfdata/iommufd-virt-pci-bus-single.aarch64-latest.args create mode 100644 tests/qemuxmlconfdata/iommufd-virt-pci-bus-single.aarch64-latest.xml create mode 100644 tests/qemuxmlconfdata/iommufd-virt-pci-bus-single.xml create mode 100644 tests/qemuxmlconfdata/iommufd-virt.aarch64-latest.args create mode 100644 tests/qemuxmlconfdata/iommufd-virt.aarch64-latest.xml create mode 100644 tests/qemuxmlconfdata/iommufd-virt.xml create mode 100644 tests/qemuxmlconfdata/iommufd.x86_64-latest.args create mode 100644 tests/qemuxmlconfdata/iommufd.x86_64-latest.xml create mode 100644 tests/qemuxmlconfdata/iommufd.xml -- 2.43.0

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[PATCH 0/2] target/arm: Deprecate '-cpu any'
by Philippe Mathieu-Daudé 02 Feb '26

02 Feb '26

Arm '-cpu any' is aliased to '-cpu max' since more than 5 years. Deprecate the former in preparation of removal. Philippe Mathieu-Daudé (2): target/arm: Remove dead code target/arm: Deprecate '-cpu any' (remplaced by '-cpu max') docs/about/deprecated.rst | 8 ++++++++ target/arm/cpu.c | 1 + target/arm/tcg/cpu32.c | 3 --- 3 files changed, 9 insertions(+), 3 deletions(-) -- 2.52.0

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