Re: [PATCH] perf: qcom_l2_pmu: don't allow guest access
- Date: Wed, 6 Dec 2017 16:11:50 +0000
- From: Mark Rutland <mark.rutland@xxxxxxx>
- Subject: Re: [PATCH] perf: qcom_l2_pmu: don't allow guest access
On Wed, Dec 06, 2017 at 10:55:33AM -0500, Neil Leeder wrote:
> Guests cannot access IMPDEF system registers, which are used
> by this driver. Disable the driver if it's running in a guest VM.
> Signed-off-by: Neil Leeder <nleeder@xxxxxxxxxxxxxx>
> drivers/perf/qcom_l2_pmu.c | 4 ++++
> 1 file changed, 4 insertions(+)
I'm a little confused by this. Why is this hypervisor providing a
QCOM8130 device to the guest that it cannot use?
Could you elaborate on what's going on?
> diff --git a/drivers/perf/qcom_l2_pmu.c b/drivers/perf/qcom_l2_pmu.c
> index 4fdc848..49dc954 100644
> --- a/drivers/perf/qcom_l2_pmu.c
> +++ b/drivers/perf/qcom_l2_pmu.c
> @@ -1057,6 +1057,10 @@ static int __init register_l2_cache_pmu_driver(void)
> int err;
> + /* Don't enable driver if running as guest */
> + if (!is_hyp_mode_available())
> + return 0;
> err = cpuhp_setup_state_multi(CPUHP_AP_PERF_ARM_QCOM_L2_ONLINE,
> Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies Inc.
> Qualcomm Technologies, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project.