Re: [PATCH] perf: qcom_l2_pmu: don't allow guest access
- Date: Wed, 6 Dec 2017 16:19:24 -0500
- From: "Leeder, Neil" <nleeder@xxxxxxxxxxxxxx>
- Subject: Re: [PATCH] perf: qcom_l2_pmu: don't allow guest access
On 12/6/2017 11:11 AM, Mark Rutland wrote:
> 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(+)
> Hi Neil,
> 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?
While there's an argument that the guest shouldn't be loading the driver
in the first place, we can't control everyone's guest configuration or what
their hypervisor does.
>> 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.
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.