kernel/linux.git/drivers/virtio/Makefile, branch v6.19.11

virtio_rtc: Add RTC class driver

2025-05-27T14:27:54+00:00

Expose the virtio-rtc UTC-like clock as an RTC clock to userspace - if it is present, and if it does not step on leap seconds. The RTC class enables the virtio-rtc device to resume the system from sleep states on RTC alarm. Support RTC alarm if the virtio-rtc alarm feature is present. The virtio-rtc device signals an alarm by marking an alarmq buffer as used. Peculiarities ------------- A virtio-rtc clock is a bit special for an RTC clock in that - the clock may step (also backwards) autonomously at any time and - the device, and its notification mechanism, will be reset during boot or resume from sleep. The virtio-rtc device avoids that the driver might miss an alarm. The device signals an alarm whenever the clock has reached or passed the alarm time, and also when the device is reset (on boot or resume from sleep), if the alarm time is in the past. Open Issue ---------- The CLOCK_BOOTTIME_ALARM will use the RTC clock to wake up from sleep, and implicitly assumes that no RTC clock steps will occur during sleep. The RTC class driver does not know whether the current alarm is a real-time alarm or a boot-time alarm. Perhaps this might be handled by the driver also setting a virtio-rtc monotonic alarm (which uses a clock similar to CLOCK_BOOTTIME_ALARM). The virtio-rtc monotonic alarm would just be used to wake up in case it was a CLOCK_BOOTTIME_ALARM alarm. Otherwise, the behavior should not differ from other RTC class drivers. Signed-off-by: Peter Hilber Acked-by: Alexandre Belloni Message-Id: <20250509160734.1772-5-quic_philber@quicinc.com> Signed-off-by: Michael S. Tsirkin

virtio_rtc: Add Arm Generic Timer cross-timestamping

2025-05-27T14:27:54+00:00

For platforms using the Arm Generic Timer, add precise cross-timestamping support to virtio_rtc. Always report the CP15 virtual counter as the HW counter in use by arm_arch_timer, since the Linux kernel's usage of the Arm Generic Timer should always be compatible with this. Signed-off-by: Peter Hilber Message-Id: <20250509160734.1772-4-quic_philber@quicinc.com> Signed-off-by: Michael S. Tsirkin

virtio_rtc: Add PTP clocks

2025-05-27T14:27:54+00:00

Expose the virtio_rtc clocks as PTP clocks to userspace, similar to ptp_kvm. virtio_rtc can expose multiple clocks, e.g. a UTC clock and a monotonic clock. Userspace should distinguish different clocks through the name assigned by the driver. In particular, UTC-like clocks can also be distinguished by if and how leap seconds are smeared. udev rules such as the following can be used to get different symlinks for different clock types: SUBSYSTEM=="ptp", ATTR{clock_name}=="Virtio PTP type 0/variant 0", SYMLINK += "ptp_virtio" SUBSYSTEM=="ptp", ATTR{clock_name}=="Virtio PTP type 1/variant 0", SYMLINK += "ptp_virtio_tai" SUBSYSTEM=="ptp", ATTR{clock_name}=="Virtio PTP type 2/variant 0", SYMLINK += "ptp_virtio_monotonic" SUBSYSTEM=="ptp", ATTR{clock_name}=="Virtio PTP type 3/variant 0", SYMLINK += "ptp_virtio_smear_unspecified" SUBSYSTEM=="ptp", ATTR{clock_name}=="Virtio PTP type 3/variant 1", SYMLINK += "ptp_virtio_smear_noon_linear" SUBSYSTEM=="ptp", ATTR{clock_name}=="Virtio PTP type 3/variant 2", SYMLINK += "ptp_virtio_smear_sls" SUBSYSTEM=="ptp", ATTR{clock_name}=="Virtio PTP type 4/variant 0", SYMLINK += "ptp_virtio_maybe_smeared" The preferred PTP clock reading method is ioctl PTP_SYS_OFFSET_PRECISE2, through the ptp_clock_info.getcrosststamp() op. For now, PTP_SYS_OFFSET_PRECISE2 will return -EOPNOTSUPP through a weak function. PTP_SYS_OFFSET_PRECISE2 requires cross-timestamping support for specific clocksources, which will be added in the following. If the clocksource specific code is enabled, check that the Virtio RTC device supports the respective HW counter before obtaining an actual cross-timestamp from the Virtio device. The Virtio RTC device response time may be higher than the timekeeper seqcount increment interval. Therefore, obtain the cross-timestamp before calling get_device_system_crosststamp(). As a fallback, support the ioctl PTP_SYS_OFFSET_EXTENDED2 for all platforms. Assume that concurrency issues during PTP clock removal are avoided by the posix_clock framework. Kconfig recursive dependencies prevent virtio_rtc from implicitly enabling PTP_1588_CLOCK, therefore just warn the user if PTP_1588_CLOCK is not available. Since virtio_rtc should in the future also expose clocks as RTC class devices, do not depend VIRTIO_RTC on PTP_1588_CLOCK. Signed-off-by: Peter Hilber Message-Id: <20250509160734.1772-3-quic_philber@quicinc.com> Signed-off-by: Michael S. Tsirkin

virtio_rtc: Add module and driver core

2025-05-27T14:27:54+00:00

Add the virtio_rtc module and driver core. The virtio_rtc module implements a driver compatible with the proposed Virtio RTC device specification. The Virtio RTC (Real Time Clock) device provides information about current time. The device can provide different clocks, e.g. for the UTC or TAI time standards, or for physical time elapsed since some past epoch. The driver can read the clocks with simple or more accurate methods. Implement the core, which interacts with the Virtio RTC device. Apart from this, the core does not expose functionality outside of the virtio_rtc module. Follow-up patches will expose PTP clocks and an RTC Class device. Provide synchronous messaging, which is enough for the expected time synchronization use cases through PTP clocks (similar to ptp_kvm) or RTC Class device. Signed-off-by: Peter Hilber Message-Id: <20250509160734.1772-2-quic_philber@quicinc.com> Signed-off-by: Michael S. Tsirkin

virtio: add debugfs infrastructure to allow to debug virtio features

2024-04-26T11:26:53+00:00

Currently there is no way for user to set what features the driver should obey or not, it is hard wired in the code. In order to be able to debug the device behavior in case some feature is disabled, introduce a debugfs infrastructure with couple of files allowing user to see what features the device advertises and to set filter for features used by driver. Example: $cat /sys/bus/virtio/devices/virtio0/features 1110010111111111111101010000110010000000100000000000000000000000 $ echo "5" >/sys/kernel/debug/virtio/virtio0/filter_feature_add $ cat /sys/kernel/debug/virtio/virtio0/filter_features 5 $ echo "virtio0" > /sys/bus/virtio/drivers/virtio_net/unbind $ echo "virtio0" > /sys/bus/virtio/drivers/virtio_net/bind $ cat /sys/bus/virtio/devices/virtio0/features 1110000111111111111101010000110010000000100000000000000000000000 Note that sysfs "features" now already exists, this patch does not touch it. Signed-off-by: Jiri Pirko Acked-by: Michael S. Tsirkin Signed-off-by: Paolo Abeni

virtio-pci: Introduce APIs to execute legacy IO admin commands

2023-12-19T18:51:33+00:00

Introduce APIs to execute legacy IO admin commands. It includes: io_legacy_read/write for both common and the device configuration, io_legacy_notify_info. In addition, exposing an API to check whether the legacy IO commands are supported. (i.e. virtio_pci_admin_has_legacy_io()). Those APIs will be used by the next patches from this series. Note: Unlike modern drivers which support hardware virtio devices, legacy drivers assume software-based devices: e.g. they don't use proper memory barriers on ARM, use big endian on PPC, etc. X86 drivers are mostly ok though, more or less by chance. For now, only support legacy IO on X86. Acked-by: Michael S. Tsirkin Signed-off-by: Yishai Hadas Link: https://lore.kernel.org/r/20231219093247.170936-7-yishaih@nvidia.com Signed-off-by: Alex Williamson

virtio: replace restricted mem access flag with callback

2022-08-01T05:42:49+00:00

Instead of having a global flag to require restricted memory access for all virtio devices, introduce a callback which can select that requirement on a per-device basis. For convenience add a common function returning always true, which can be used for use cases like SEV. Per default use a callback always returning false. As the callback needs to be set in early init code already, add a virtio anchor which is builtin in case virtio is enabled. Signed-off-by: Juergen Gross Tested-by: Oleksandr Tyshchenko # Arm64 guest using Xen Reviewed-by: Stefano Stabellini Link: https://lore.kernel.org/r/20220622063838.8854-2-jgross@suse.com Signed-off-by: Juergen Gross

virtio-pci: introduce legacy device module

2021-11-01T08:30:34+00:00

Split common codes from virtio-pci-legacy so vDPA driver can reuse it later. Signed-off-by: Wu Zongyong Acked-by: Jason Wang Link: https://lore.kernel.org/r/71605acde5e97fcb2760a6973e406279fb1bbd33.1635493219.git.wuzongyong@linux.alibaba.com Signed-off-by: Michael S. Tsirkin

virtio-pci: introduce modern device module

2021-02-23T12:52:58+00:00

Signed-off-by: Jason Wang Link: https://lore.kernel.org/r/20210104065503.199631-17-jasowang@redhat.com Including a bugfix: virtio: don't prompt CONFIG_VIRTIO_PCI_MODERN Cc: Arnd Bergmann Cc: Anders Roxell Cc: Guenter Roeck Reported-by: Naresh Kamboju Fixes: 86b87c9d858b6 ("virtio-pci: introduce modern device module") Signed-off-by: Jason Wang Acked-by: Arnd Bergmann Link: https://lore.kernel.org/r/20210223061905.422659-2-jasowang@redhat.com Signed-off-by: Michael S. Tsirkin

virtio: fix build for configs without dma-bufs

2020-08-19T04:43:28+00:00

Reported-by: kernel test robot Signed-off-by: David Stevens Link: http://patchwork.freedesktop.org/patch/msgid/20200819031011.310180-1-stevensd@chromium.org Signed-off-by: Gerd Hoffmann