Received-SPF: softfail (google.com: domain of transitioning linux-kernel-owner@vger.kernel.org does not designate 23.128.96.19 as permitted sender) client-ip=23.128.96.19;
Date:   Fri, 22 Apr 2022 14:19:48 +0000
Message-Id: <20220422141949.3456505-1-sebastianene@google.com>
Mime-Version: 1.0
Subject: [PATCH  v2 0/2] Detect stalls on guest vCPUS
From:   Sebastian Ene <sebastianene@google.com>
To:     Rob Herring <robh+dt@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Arnd Bergmann <arnd@arndb.de>,
        Dragan Cvetic <dragan.cvetic@xilinx.com>
Cc:     linux-kernel@vger.kernel.org, devicetree@vger.kernel.org,
        maz@kernel.org, will@kernel.org, qperret@google.com,
        Sebastian Ene <sebastianene@google.com>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

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

Changelog v2:
 - move the driver to misc as this does not cope with watchdog core
   subsystem
 - fix the dt-bindings warnings

Sebastian Ene (2):
  dt-bindings: vm-wdt: Add qemu,vm-watchdog compatible
  misc: Add a mechanism to detect stalls on guest vCPUs

 .../devicetree/bindings/misc/vm-wdt.yaml      |  44 ++++
 drivers/misc/Kconfig                          |   8 +
 drivers/misc/Makefile                         |   1 +
 drivers/misc/vm-wdt.c                         | 215 ++++++++++++++++++
 4 files changed, 268 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/misc/vm-wdt.yaml
 create mode 100644 drivers/misc/vm-wdt.c

-- 
2.36.0.rc2.479.g8af0fa9b8e-goog