Re: [PATCH v2 0/4] pseries-wdt: initial support for H_WATCHDOG-based watchdog timers

[Daniel Henrique Barboza <danielhb413@gmail.com>]

Hi,

I tried this series out with mainline QEMU built with Alexey's patch [1]
and I wasn't able to get it to work. I'm using a simple QEMU command line
booting a fedora36 guest in a Power9 boston host:

sudo  ./qemu-system-ppc64 \
-M pseries,cap-cfpc=broken,cap-sbbc=broken,cap-ibs=broken,cap-ccf-assist=off,ic-mode=dual \
-m 4G -accel kvm -cpu POWER9 -smp 1,maxcpus=1,threads=1,cores=1,sockets=1 \
-device virtio-scsi-pci,id=scsi0,bus=pci.0,addr=0x2 \
-drive file=/home/danielhb/fedora36.qcow2,if=none,id=drive-scsi0-0-0-0,format=qcow2,cache=none \
-device scsi-hd,bus=scsi0.0,channel=0,scsi-id=0,lun=0,drive=drive-scsi0-0-0-0,id=scsi0-0-0-0,bootindex=2 \
-device qemu-xhci,id=usb,bus=pci.0,addr=0x4 -nographic -display none


Guest is running v5.19-rc2 with this series applied. Kernel config consists of
'pseries_le_defconfig' plus the following 'watchdog' related changes:

[root@fedora ~]# cat linux/.config | grep PSERIES_WDT
CONFIG_PSERIES_WDT=y

[root@fedora ~]# cat linux/.config | grep -i watchdog
CONFIG_PPC_WATCHDOG=y
CONFIG_HAVE_NMI_WATCHDOG=y
CONFIG_WATCHDOG=y
CONFIG_WATCHDOG_CORE=y
CONFIG_WATCHDOG_NOWAYOUT=y
CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED=y
CONFIG_WATCHDOG_OPEN_TIMEOUT=0
# CONFIG_WATCHDOG_SYSFS is not set
# CONFIG_WATCHDOG_HRTIMER_PRETIMEOUT is not set
# Watchdog Pretimeout Governors
# CONFIG_WATCHDOG_PRETIMEOUT_GOV is not set
# Watchdog Device Drivers
# CONFIG_SOFT_WATCHDOG is not set
# CONFIG_XILINX_WATCHDOG is not set
# CONFIG_ZIIRAVE_WATCHDOG is not set
# CONFIG_CADENCE_WATCHDOG is not set
# CONFIG_DW_WATCHDOG is not set
# CONFIG_MAX63XX_WATCHDOG is not set
CONFIG_WATCHDOG_RTAS=y
# PCI-based Watchdog Cards
# CONFIG_PCIPCWATCHDOG is not set
# USB-based Watchdog Cards
# CONFIG_USBPCWATCHDOG is not set
# CONFIG_WQ_WATCHDOG is not set
[root@fedora ~]#



Kernel command line:

[root@fedora ~]# cat /proc/cmdline
BOOT_IMAGE=(ieee1275/disk,msdos2)/vmlinuz-5.19.0-rc2-00054-g12ede8ffb103 \
root=/dev/mapper/fedora_fedora-root ro rd.lvm.lv=fedora_fedora/root \
pseries-wdt.timeout=60 pseries-wdt.nowayout=1 pseries-wdt.action=2


With all that, executing

echo V > /dev/watchdog0

Does nothing. dmesg is clean and the guest doesn't reboot after the 60 sec
timeout.  I also tried with PSERIES_WDT being compiled as a module instead
of built-in. Same results.


What am I missing?


[1] https://patchwork.ozlabs.org/project/qemu-ppc/patch/20220608030153.1862335-1-aik@ozlabs.ru/



Thanks,


Daniel




On 6/2/22 14:53, Scott Cheloha wrote:
> PAPR v2.12 defines a new hypercall, H_WATCHDOG.  This patch series
> adds support for this hypercall to powerpc/pseries kernels and
> introduces a new watchdog driver, "pseries-wdt", for the virtual
> timers exposed by the hypercall.
> 
> This series is preceded by the following:
> 
> RFC v1: https://lore.kernel.org/linux-watchdog/20220413165104.179144-1-cheloha@linux.ibm.com/
> RFC v2: https://lore.kernel.org/linux-watchdog/20220509174357.5448-1-cheloha@linux.ibm.com/
> PATCH v1: https://lore.kernel.org/linux-watchdog/20220520183552.33426-1-cheloha@linux.ibm.com/
> 
> Changes of note from PATCH v1:
> 
> - Trim down the large comment documenting the H_WATCHDOG hypercall.
>    The comment is likely to rot, so remove anything we aren't using
>    and anything overly obvious.
> 
> - Remove any preprocessor definitions not actually used in the module
>    right now.  If we want to use other features offered by the hypercall
>    we can add them in later.  They're just clutter until then.
> 
> - Simplify the "action" module parameter.  The value is now an index
>    into an array of possible timeoutAction values.  This design removes
>    the need for the custom get/set methods used in PATCH v1.
> 
>    Now we merely need to check that the "action" value is a valid
>    index during pseries_wdt_probe().  Easy.
> 
> - Make the timeoutAction a member of pseries_wdt, "action".  This
>    eliminates the use of a global variable during pseries_wdt_start().
> 
> - Use watchdog_init_timeout() idiomatically.  Check its return value
>    and error out of pseries_wdt_probe() if it fails.
> 
>