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[RFC] x86 Host CPU features detection by MSRs
by Hector Cao 12 Aug '25

12 Aug '25

Hello, This mail is a Request for Comment. On recent Intel CPUs, some of the CPU features (mostly vmx-* subfeatures) are listed and controlled via the MSRs (Model Specific Registers) instead of the traditional CPUID instruction method. Right now, libvirt reads the MSR's values via /dev/cpu/*/cpu populated by the msr kernel module. src/cpu/cpu_x86.c: ... /* This is best effort since there might be no way to read the MSR * when we are not running as root. */ for (i = 0; i < nmsrs; i++) { if (virHostCPUGetMSR(msrs[i], &msr) == 0) { virCPUx86DataItem item = { .type = VIR_CPU_X86_DATA_MSR, .data.msr = { ... There are 2 potential issues: 1) As stated in the source code comment above, MSR values read might fail when libvirt is not run as root. 2) MSR values read might fail if the MSR kernel module is not loaded, this is still the case in some of the Linux distros. The issue 2) has been brought up in Ubuntu/Debian : https://salsa.debian.org/libvirt-team/libvirt/-/merge_requests/271 but the feedback was to try to fix the issue in the libvirt source code itself. Indeed, libvirt already loads some kernel modules it depends on. For example the NBD kernel module in src/util/virtfile.c ... static bool virFileNBDLoadDriver(void) { if (virKModIsProhibited(NBD_DRIVER)) { virReportError(VIR_ERR_INTERNAL_ERROR, "%s", _("Failed to load nbd module: administratively prohibited")); return false; } else { g_autofree char *errbuf = NULL; if ((errbuf = virKModLoad(NBD_DRIVER))) { virReportError(VIR_ERR_INTERNAL_ERROR, "%s", _("Failed to load nbd module")); ... Andrea Bolognani's proposal of an approach that could work: 1. try using the unprivileged KVM API is available (or maybe the necessary information is exposed via QMP too?) like how QEMU does; 2. if that fails, try using the privileged /dev API; 3. if that fails too, load the msr module and try again; I would like to have some feedback from the libvirt community about if that is worth tackling these issues and the right way to do that. If we can end up with an agreement in this mail thread, I can work on the solution implementation and send it in a separate submission. Best regards, Hector

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[PATCH v2 0/2] Remove libnl checks specific to Linux
by Akihiko Odaki 12 Aug '25

12 Aug '25

Supersedes: <20250308-require-v1-1-fe6850bf3f30(a)daynix.com> ("[PATCH] util: Require libnl for Linux") Based on previous discussions, this implements yet another approach to fix builds without libnl for Linux. Signed-off-by: Akihiko Odaki <odaki(a)rsg.ci.i.u-tokyo.ac.jp> --- Changes in v2: - Rebased. - Link to v1: https://lore.kernel.org/r/20250312-linux-v1-0-e5531bbe9708@daynix.com --- Akihiko Odaki (2): Remove libnl checks specific to Linux virnetlink: Remove stub functions src/libvirt_libnl.syms | 23 +++++ src/libvirt_private.syms | 19 ---- src/meson.build | 6 ++ src/remote/remote_daemon.c | 10 ++- src/util/meson.build | 5 +- src/util/virarptable.c | 2 +- src/util/virnetdev.c | 44 +-------- src/util/virnetdevbridge.c | 29 +----- src/util/virnetlink.c | 216 +++------------------------------------------ src/util/virnetlink.h | 11 +-- tests/virnetdevtest.c | 10 +-- 11 files changed, 64 insertions(+), 311 deletions(-) --- base-commit: 5085c7fd030ed4322608de1128811fc3bf61e201 change-id: 20250312-linux-30e6e1af51a5 Best regards, -- Akihiko Odaki <odaki(a)rsg.ci.i.u-tokyo.ac.jp>

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[PATCH 0/2] qemu: Match firmware with fully resolved and canonicalized paths
by Michal Privoznik 12 Aug '25

12 Aug '25

As promised, this is a resend of previous patches: https://lists.libvirt.org/archives/list/devel@lists.libvirt.org/thread/XVHI… Diff to v1: - new patch 1/2 which fixes the mocking. James Le Cuirot (1): qemu: Match firmware with fully resolved and canonicalized paths Michal Prívozník (1): qemuxml2argvmock: Pretend FW blobs are always present src/qemu/qemu_firmware.c | 11 ++++++----- tests/qemuxml2argvmock.c | 35 +++++++++++++++++++++++++++++++++++ 2 files changed, 41 insertions(+), 5 deletions(-) -- 2.49.1

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[PATCH] ci: regenerate with 'lcitool manifest'
by Daniel P. Berrangé 04 Aug '25

04 Aug '25

From: Daniel P. Berrangé <berrange(a)redhat.com> This pulls in the fix for libxen which has been removed from armv7 in Debian sid. Signed-off-by: Daniel P. Berrangé <berrange(a)redhat.com> --- Pending: https://gitlab.com/libvirt/libvirt-ci/-/merge_requests/537 ci/buildenv/debian-sid-cross-armv7l.sh | 1 - ci/containers/debian-sid-cross-armv7l.Dockerfile | 1 - 2 files changed, 2 deletions(-) diff --git a/ci/buildenv/debian-sid-cross-armv7l.sh b/ci/buildenv/debian-sid-cross-armv7l.sh index e014b3dd0f..3d662d73ed 100644 --- a/ci/buildenv/debian-sid-cross-armv7l.sh +++ b/ci/buildenv/debian-sid-cross-armv7l.sh @@ -77,7 +77,6 @@ function install_buildenv() { libssh2-1-dev:armhf \ libtirpc-dev:armhf \ libudev-dev:armhf \ - libxen-dev:armhf \ libxml2-dev:armhf \ systemtap-sdt-dev:armhf mkdir -p /usr/local/share/meson/cross diff --git a/ci/containers/debian-sid-cross-armv7l.Dockerfile b/ci/containers/debian-sid-cross-armv7l.Dockerfile index e6118a0d9b..5aaf29d22a 100644 --- a/ci/containers/debian-sid-cross-armv7l.Dockerfile +++ b/ci/containers/debian-sid-cross-armv7l.Dockerfile @@ -88,7 +88,6 @@ RUN export DEBIAN_FRONTEND=noninteractive && \ libssh2-1-dev:armhf \ libtirpc-dev:armhf \ libudev-dev:armhf \ - libxen-dev:armhf \ libxml2-dev:armhf \ systemtap-sdt-dev:armhf && \ eatmydata apt-get autoremove -y && \ -- 2.50.1

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[PATCH v2 0/2] Introduce hardware UUID (hwuuid) element
by Mark Cave-Ayland 04 Aug '25

04 Aug '25

Following on from the discussions at [1] and more recently [2], this series introduces a new hardware UUID (hwuuid) element that allows an external UUID to be provided to the guest, as opposed to the libvirt domain UUID. The use case for this feature is to allow a domain to cloned and then restarted without changing its guest-visible UUID e.g. via dmidecode. Patch 1 introduces the new hardware UUID (hwuuid) element along with an implementation for the QEMU driver, whilst patch 2 adds additional tests to ensure the hwuuid functionality is working as expected. Note that from reading the source it doesn't appear as if all virtualisation platforms will support this feature: I've included the relevant changes for the QEMU driver since that is what we use here at Nutanix. Signed-off-by: Mark Cave-Ayland <mark.caveayland(a)nutanix.com> [1] https://lists.libvirt.org/archives/list/devel@lists.libvirt.org/thread/YXN2… [2] https://lists.libvirt.org/archives/list/devel@lists.libvirt.org/thread/HGFT… v2: - Rebase onto master - Rework if() logic in virSysinfoSystemParseXML() in patch 1 as suggested by Daniel - Add R-B tag from Daniel to patch 2 Mark Cave-Ayland (2): conf: introduce hardware UUID (hwuuid) element qemuxmlconftest: add tests for new hardware UUID (hwuuid) element docs/formatdomain.rst | 7 +++ src/conf/domain_conf.c | 43 ++++++++++++++++--- src/conf/domain_conf.h | 1 + src/conf/schemas/domaincommon.rng | 5 +++ src/qemu/qemu_command.c | 6 ++- ...hwuuid-smbios-uuid-match.x86_64-latest.err | 1 + .../hwuuid-smbios-uuid-match.xml | 36 ++++++++++++++++ .../qemuxmlconfdata/hwuuid.x86_64-latest.args | 35 +++++++++++++++ .../qemuxmlconfdata/hwuuid.x86_64-latest.xml | 41 ++++++++++++++++++ tests/qemuxmlconfdata/hwuuid.xml | 30 +++++++++++++ tests/qemuxmlconftest.c | 3 ++ 11 files changed, 202 insertions(+), 6 deletions(-) create mode 100644 tests/qemuxmlconfdata/hwuuid-smbios-uuid-match.x86_64-latest.err create mode 100644 tests/qemuxmlconfdata/hwuuid-smbios-uuid-match.xml create mode 100644 tests/qemuxmlconfdata/hwuuid.x86_64-latest.args create mode 100644 tests/qemuxmlconfdata/hwuuid.x86_64-latest.xml create mode 100644 tests/qemuxmlconfdata/hwuuid.xml -- 2.43.0

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Release of libvirt-11.6.0
by Jiri Denemark 01 Aug '25

01 Aug '25

The 11.6.0 release of both libvirt and libvirt-python is tagged and signed tarballs are available at https://download.libvirt.org/ https://download.libvirt.org/python/ Thanks everybody who helped with this release by sending patches, reviewing, testing, or providing feedback. Your work is greatly appreciated. * New features * Introduce VIR_CONNECT_BASELINE_CPU_IGNORE_HOST flag This new flag for virConnectBaselineHypervisorCPU can be used for computing a baseline CPU on any host. Without the VIR_CONNECT_BASELINE_CPU_IGNORE_HOST flag the baseline API would return reasonable output only when run on one of the hosts that the input CPU definitions were collected from. * Allow control over QEMU TLS priority strings The qemu.conf file now has multiple settings allowing control over the QEMU TLS priority strings, for the different subsystems in QEMU that can support TLS. This can be used to workaround a current bug in GNUTLS that is liable to cause crashes of the source QEMU when performing long running live migration operations with TLS enabled. * Add support for disabling deprecated CPU model features by default for s390 domains Starting an s390 domain with host-model will now default to setting the ``deprecated_features`` attribute to ``off``, ensuring the domain starts with a migration-compatible CPU model to newer systems. This behavior can be modified by setting the ``default_cpu_deprecated_features`` option in the qemu.conf file. * bhyve: Add TCP console support TCP serial devices can now be configured with ``<serial type='tcp'>``:: <serial type='tcp'> <source mode='bind' host='127.0.0.1' service='12345'/> <target type='serial' port='0'/> </serial> Additionally, number of supported consoles increased to 4. * qemu: Add support for RBD namespaces Allow specifying the 'namespace' within a RBD image pool. * Improvements * qemu: Change default SCSI controller model to ``virtio-scsi`` for ARM and RISC-V The previous default of ``lsilogic`` is unsupported by modern operating systems. ``virtio-scsi`` is a more suitable default for ARM and RISC-V ``virt`` machine types. * Clarify documentation of virConnectBaselineHypervisorCPU The documentation makes it clear virConnectBaselineHypervisorCPU is supposed to be called on one of the hosts represented in the input CPU definitions. Otherwise the API will give unexpected results. * Allow specifying zero discard granularity for block devices This can be used to tell some guest operating systems (notably Windows) to not trim the disk. * bhyve: Add timeout handling for bhyveload It is now possible to run ``bhyveload`` with the ``timeout`` tool, which can send ``SIGTERM`` and ``SIGKILL`` signals when timeout is reached. Timeout values are set using the ``bhyveload_timeout`` and ``bhyveload_timeout_kill`` configuration options in ``bhyve.conf``. * nss: Improve debugging Debugging messages from NSS modules can be now enabled by setting the ``LIBVIRT_NSS_DEBUG`` environment variable. So far, there is no special meaning to its value. * rpc: Removed requirement for TLS certificates to support 'key encipherment' With TLS 1.3, key encipherment is not required even for RSA keys. Other key types didn't even support it so they were wrongly refused even in cases when they would work with libvirt. The TLS certificate validation now no longer requires 'key encipherment' to be enabled. * Bug fixes * bhyve: Fix resetting of the autostart flag of the domain on destroy. * The nwfilter driver no longer recreates the base iptable/ip6tables chains The nwfilter driver had a impl mistake causing it to recreate the base chains for iptables/ip6tables every time a VM was started. This allowed a small window where traffic might not be fully filtered. It now handles iptables/ip6tables the same way as ebtables, creating the base chains only if they did not already exist. * Fix systemd unit ordering for auto-shutdown of domains via the daemon The ordering of systemd units created by libvirt for individual machines needed to be adapted when the shutdown of VMs on host shutdown is done via the virt daemon itself (rather than ``libvirt-guests.service``) to ensure that the VMs are not terminated before the virt daemon can deal with them. Enjoy. Jirka

1 0

[PATCH] conf: add support for 'edid' attribute to video model
by Mark Cave-Ayland 01 Aug '25

01 Aug '25

Add the ability to enable/disable exposing the EDID information to the guest. This allows migration from legacy machine types that have EDID disabled to a newer machine type without any change becoming visible to the guest. The edid attribute can specified in the domain XML as below: <video> <model type='virtio' edid='off'/> </video> If the edid attribute is unspecified, it is not generated so that the virtualisation platform will continue to use its default. The edid attribute is only valid for the vga, boch and virtio display models and is currently only implemented for the QEMU driver. Signed-off-by: Mark Cave-Ayland <mark.caveayland(a)nutanix.com> --- docs/formatdomain.rst | 8 ++++++++ src/conf/domain_conf.c | 5 +++++ src/conf/domain_conf.h | 1 + src/conf/domain_validate.c | 11 +++++++++++ src/conf/schemas/domaincommon.rng | 5 +++++ src/qemu/qemu_command.c | 7 +++++++ 6 files changed, 37 insertions(+) diff --git a/docs/formatdomain.rst b/docs/formatdomain.rst index 976746e292..7fe8b03a56 100644 --- a/docs/formatdomain.rst +++ b/docs/formatdomain.rst @@ -7103,6 +7103,14 @@ A video device. sub-element is valid for model types "vga", "qxl", "bochs", "gop", and "virtio". + :since:`Since 11.7.0` (QEMU driver only), the ``model`` element may have an + optional ``edid`` attribute that can be set to "on" or "off". If the ``edid`` + attribute is not specified then the device will use its default value. + Otherwise setting ``edid`` to "on" will expose the device EDID blob to the + guest, whilst setting it to "off" will hide the device EDID blob from the + guest. The ``edid`` attribute is only valid for model types "vga", "bochs", + and "virtio". + ``acceleration`` Configure if video acceleration should be enabled. diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c index 59958c2f08..10cc6d7432 100644 --- a/src/conf/domain_conf.c +++ b/src/conf/domain_conf.c @@ -13535,6 +13535,9 @@ virDomainVideoModelDefParseXML(virDomainVideoDef *def, if (virXMLPropTristateSwitch(node, "blob", VIR_XML_PROP_NONE, &def->blob) < 0) return -1; + if (virXMLPropTristateSwitch(node, "edid", VIR_XML_PROP_NONE, &def->edid) < 0) + return -1; + return 0; } @@ -26629,6 +26632,8 @@ virDomainVideoDefFormat(virBuffer *buf, virBufferAddLit(buf, " primary='yes'"); if (def->blob != VIR_TRISTATE_SWITCH_ABSENT) virBufferAsprintf(buf, " blob='%s'", virTristateSwitchTypeToString(def->blob)); + if (def->edid != VIR_TRISTATE_SWITCH_ABSENT) + virBufferAsprintf(buf, " edid='%s'", virTristateSwitchTypeToString(def->edid)); if (def->accel || def->res) { virBufferAddLit(buf, ">\n"); virBufferAdjustIndent(buf, 2); diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h index 596d138973..425ccfa97c 100644 --- a/src/conf/domain_conf.h +++ b/src/conf/domain_conf.h @@ -1895,6 +1895,7 @@ struct _virDomainVideoDef { virDomainDeviceInfo info; virDomainVirtioOptions *virtio; virDomainVideoBackendType backend; + virTristateSwitch edid; }; /* graphics console modes */ diff --git a/src/conf/domain_validate.c b/src/conf/domain_validate.c index 40edecef83..60a2e46b7e 100644 --- a/src/conf/domain_validate.c +++ b/src/conf/domain_validate.c @@ -231,6 +231,17 @@ virDomainVideoDefValidate(const virDomainVideoDef *video, } } + if ((video->type != VIR_DOMAIN_VIDEO_TYPE_BOCHS) && + (video->type != VIR_DOMAIN_VIDEO_TYPE_VGA) && + (video->type != VIR_DOMAIN_VIDEO_TYPE_VIRTIO)) { + if (video->edid != VIR_TRISTATE_SWITCH_ABSENT) { + virReportError(VIR_ERR_CONFIG_UNSUPPORTED, + _("video type '%1$s' does not support edid"), + virDomainVideoTypeToString(video->type)); + return -1; + } + } + return 0; } diff --git a/src/conf/schemas/domaincommon.rng b/src/conf/schemas/domaincommon.rng index a714c3fcc5..d84f20637c 100644 --- a/src/conf/schemas/domaincommon.rng +++ b/src/conf/schemas/domaincommon.rng @@ -4807,6 +4807,11 @@ <ref name="virOnOff"/> </attribute> </optional> + <optional> + <attribute name="edid"> + <ref name="virOnOff"/> + </attribute> + </optional> <optional> <element name="acceleration"> <optional> diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c index 457dee7029..db00f9b173 100644 --- a/src/qemu/qemu_command.c +++ b/src/qemu/qemu_command.c @@ -4739,6 +4739,13 @@ qemuBuildDeviceVideoCmd(virCommand *cmd, return -1; } + if ((video->type == VIR_DOMAIN_VIDEO_TYPE_BOCHS) || + (video->type == VIR_DOMAIN_VIDEO_TYPE_VGA) || + (video->type == VIR_DOMAIN_VIDEO_TYPE_VIRTIO)) { + if (virJSONValueObjectAdd(&props, "T:edid", video->edid, NULL) < 0) + return -1; + } + if (video->res) { if (virJSONValueObjectAdd(&props, "p:xres", video->res->x, -- 2.43.0

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[PATCH] NEWS: Mention RBD namespaces, and auto-shutdown/key encipherment fixes
by Peter Krempa 31 Jul '25

31 Jul '25

From: Peter Krempa <pkrempa(a)redhat.com> Signed-off-by: Peter Krempa <pkrempa(a)redhat.com> --- NEWS.rst | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/NEWS.rst b/NEWS.rst index 5a320b7f33..6db9c998d9 100644 --- a/NEWS.rst +++ b/NEWS.rst @@ -51,6 +51,10 @@ v11.6.0 (unreleased) Additionally, number of supported consoles increased to 4. + * qemu: Add support for RBD namespaces + + Allow specifying the 'namespace' within a RBD image pool. + * **Improvements** * qemu: Change default SCSI controller model to ``virtio-scsi`` for ARM and RISC-V @@ -83,6 +87,13 @@ v11.6.0 (unreleased) ``LIBVIRT_NSS_DEBUG`` environment variable. So far, there is no special meaning to its value. + * rpc: Removed requirement for TLS certificates to support 'key encipherment' + + With TLS 1.3, key encipherment is not required even for RSA keys. Other key + types didn't even support it so they were wrongly refused even in cases when + they would work with libvirt. The TLS certificate validation now no longer + requires 'key encipherment' to be enabled. + * **Bug fixes** * bhyve: Fix resetting of the autostart flag of the domain on destroy. @@ -96,6 +107,14 @@ v11.6.0 (unreleased) ebtables, creating the base chains only if they did not already exist. + * Fix systemd unit ordering for auto-shutdown of domains via the daemon + + The ordering of systemd units created by libvirt for individual machines + needed to be adapted when the shutdown of VMs on host shutdown is done + via the virt daemon itself (rather than ``libvirt-guests.service``) to + ensure that the VMs are not terminated before the virt daemon can deal with + them. + v11.5.0 (2025-07-01) ==================== -- 2.50.1

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Question about SEV* guests and automatic firmware selection
by Jim Fehlig 31 Jul '25

31 Jul '25

Hi All, While investigating an internal bug report, we noticed that a minimal firmware auto-selection configuration along with SEV* fails to find a match. E.g. the following config <domain type="kvm"> <os firmware="efi"> <type arch="x86_64" machine="q35">hvm</type> <boot dev="hd"/> </os> <launchSecurity type="sev"> <policy>0x07</policy> </launchSecurity> ... </domain> Fails with "Unable to find 'efi' firmware that is compatible with the current configuration". A firmware that should match has the following json description { "description": "UEFI firmware for x86_64, with AMD SEV", "interface-types": [ "uefi" ], "mapping": { "device": "flash", "mode": "stateless", "executable": { "filename": "/usr/share/qemu/ovmf-x86_64-sev.bin", "format": "raw" } }, "targets": [ { "architecture": "x86_64", "machines": [ "pc-q35-*" ] } ], "features": [ "acpi-s4", "amd-sev", "amd-sev-es", "amd-sev-snp", "verbose-dynamic" ], "tags": [ ] } Auto-selection works fine if I specify a 'stateless' firmware, e.g. amend the above config with <os firmware="efi"> <type arch="x86_64" machine="q35">hvm</type> <loader stateless="yes"/> <boot dev="hd"/> </os> Being unfamiliar with the firmware auto-selection code, I tried the below naive hack, which only led to test failures and the subsequent runtime error "unable to find any master var store for loader: /usr/share/qemu/ovmf-x86_64-sev.bin". Should auto-selection work with the minimal config, or is it expected that user also specify a stateless firmware? Regards, Jim diff --git a/src/qemu/qemu_firmware.c b/src/qemu/qemu_firmware.c index 2d0ec0b4fa..660b74141a 100644 --- a/src/qemu/qemu_firmware.c +++ b/src/qemu/qemu_firmware.c @@ -1293,15 +1293,17 @@ qemuFirmwareMatchDomain(const virDomainDef *def, return false; } - if (loader && loader->stateless == VIR_TRISTATE_BOOL_YES) { - if (flash->mode != QEMU_FIRMWARE_FLASH_MODE_STATELESS) { - VIR_DEBUG("Discarding loader without stateless flash"); - return false; - } - } else { - if (flash->mode != QEMU_FIRMWARE_FLASH_MODE_SPLIT) { - VIR_DEBUG("Discarding loader without split flash"); - return false; + if (loader) { + if (loader->stateless == VIR_TRISTATE_BOOL_YES) { + if (flash->mode != QEMU_FIRMWARE_FLASH_MODE_STATELESS) { + VIR_DEBUG("Discarding loader without stateless flash"); + return false; + } + } else if (loader->stateless == VIR_TRISTATE_BOOL_NO) { + if (flash->mode != QEMU_FIRMWARE_FLASH_MODE_SPLIT) { + VIR_DEBUG("Discarding loader without split flash"); + return false; + } } }

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[PATCH] news: document fixed nwfilter driver base chain creation
by Daniel P. Berrangé 30 Jul '25

30 Jul '25

From: Daniel P. Berrangé <berrange(a)redhat.com> Signed-off-by: Daniel P. Berrangé <berrange(a)redhat.com> --- NEWS.rst | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/NEWS.rst b/NEWS.rst index e5e8626729..c7bfac1db4 100644 --- a/NEWS.rst +++ b/NEWS.rst @@ -48,6 +48,14 @@ v11.6.0 (unreleased) * **Bug fixes** + * The nwfilter driver no longer recreates the base iptable/ip6tables chains + + The nwfilter driver had a impl mistake causing it to recreate the + base chains for iptables/ip6tables every time a VM was started. + This allowed a small window where traffic might not be fully + filtered. It now handles iptables/ip6tables the same way as + ebtables, creating the base chains only if they did not already + exist. v11.5.0 (2025-07-01) ==================== -- 2.50.1

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