This adds a mechanism to detect stalls on the guest vCPUS by creating a per CPU hrtimer which periodically 'pets' the host backend driver. This device driver acts as a soft lockup detector by relying on the host backend driver to measure the elapesed time between subsequent 'pet' events. If the elapsed time doesn't match an expected value, the backend driver decides that the guest vCPU is locked and resets the guest. The host backend driver takes into account the time that the guest is not running. The communication with the backend driver is done through MMIO and the register layout of the virtual watchdog is described as part of the backend driver changes. The host backend driver is implemented as part of: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/3548817 Sebastian Ene (2): dt-bindings: watchdog: Add qemu,vm-watchdog compatible watchdog: Add a mechanism to detect stalls on guest vCPUs .../devicetree/bindings/watchdog/vm-wdt.yaml | 44 ++++ drivers/watchdog/Kconfig | 8 + drivers/watchdog/Makefile | 1 + drivers/watchdog/vm-wdt.c | 215 ++++++++++++++++++ 4 files changed, 268 insertions(+) create mode 100644 Documentation/devicetree/bindings/watchdog/vm-wdt.yaml create mode 100644 drivers/watchdog/vm-wdt.c -- 2.35.1.1094.g7c7d902a7c-goog
