> Add a function to inform Hyper-V about a guest panic.
>
> This code is built only when CONFIG_HYPERV is enabled.
>
> Signed-off-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>
> ---
> arch/arm64/hyperv/hv_core.c | 52 +++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 52 insertions(+)
>
> diff --git a/arch/arm64/hyperv/hv_core.c b/arch/arm64/hyperv/hv_core.c
> index 4c5dc0f..b54c347 100644
> --- a/arch/arm64/hyperv/hv_core.c
> +++ b/arch/arm64/hyperv/hv_core.c
> @@ -127,3 +127,55 @@ u64 hv_get_vpreg(u32 msr)
> return output.as64.low;
> }
> EXPORT_SYMBOL_GPL(hv_get_vpreg);
> +
> +/*
> + * hyperv_report_panic - report a panic to Hyper-V. This function uses
> + * the older version of the Hyper-V interface that admittedly doesn't
> + * pass enough information to be useful beyond just recording the
> + * occurrence of a panic. The parallel hv_kmsg_dump() uses the
> + * new interface that allows reporting 4 Kbytes of data, which is much
> + * more useful. Hyper-V on ARM64 always supports the newer interface, but
> + * we retain support for the older version because the sysadmin is allowed
> + * to disable the newer version via sysctl in case of information security
> + * concerns about the more verbose version.
> + */
> +void hyperv_report_panic(struct pt_regs *regs, long err, bool in_die)
> +{
> + static bool panic_reported;
> + u64 guest_id;
> +
> + /* Don't report a panic to Hyper-V if we're not going to panic */
> + if (in_die && !panic_on_oops)
> + return;
> +
> + /*
> + * We prefer to report panic on 'die' chain as we have proper
> + * registers to report, but if we miss it (e.g. on BUG()) we need
> + * to report it on 'panic'.
> + *
> + * Calling code in the 'die' and 'panic' paths ensures that only
> + * one CPU is running this code, so no atomicity is needed.
> + */
> + if (panic_reported)
> + return;
> + panic_reported = true;
> +
> + guest_id = hv_get_vpreg(HV_REGISTER_GUEST_OSID);
> +
> + /*
> + * Hyper-V provides the ability to store only 5 values.
> + * Pick the passed in error value, the guest_id, the PC,
> + * and the SP.
> + */
> + hv_set_vpreg(HV_REGISTER_CRASH_P0, err);
> + hv_set_vpreg(HV_REGISTER_CRASH_P1, guest_id);
> + hv_set_vpreg(HV_REGISTER_CRASH_P2, regs->pc);
> + hv_set_vpreg(HV_REGISTER_CRASH_P3, regs->sp);
> + hv_set_vpreg(HV_REGISTER_CRASH_P4, 0);
> +
> + /*
> + * Let Hyper-V know there is crash data available
> + */
> + hv_set_vpreg(HV_REGISTER_CRASH_CTL, HV_CRASH_CTL_CRASH_NOTIFY);
> +}
> +EXPORT_SYMBOL_GPL(hyperv_report_panic);
> --
> 1.8.3.1
Reviewed-by: Sunil Muthuswamy <sunilmut@xxxxxxxxxxxxx>
