Re: [PATCH v4 20/23] arm64: perf: Count EL2 events if the kernel is running in HYP
From: Will Deacon
Date: Mon Feb 15 2016 - 12:22:47 EST
On Thu, Feb 11, 2016 at 06:40:01PM +0000, Marc Zyngier wrote:
> When the kernel is running in HYP (with VHE), it is necessary to
> include EL2 events if the user requests counting kernel or
> hypervisor events.
>
> Reviewed-by: Christoffer Dall <christoffer.dall@xxxxxxxxxx>
> Acked-by: Catalin Marinas <catalin.marinas@xxxxxxx>
> Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
> ---
> arch/arm64/kernel/perf_event.c | 14 ++++++++++----
> 1 file changed, 10 insertions(+), 4 deletions(-)
>
> diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c
> index f7ab14c..6013a38 100644
> --- a/arch/arm64/kernel/perf_event.c
> +++ b/arch/arm64/kernel/perf_event.c
> @@ -20,6 +20,7 @@
> */
>
> #include <asm/irq_regs.h>
> +#include <asm/virt.h>
>
> #include <linux/of.h>
> #include <linux/perf/arm_pmu.h>
> @@ -693,10 +694,15 @@ static int armv8pmu_set_event_filter(struct hw_perf_event *event,
> return -EPERM;
> if (attr->exclude_user)
> config_base |= ARMV8_EXCLUDE_EL0;
> - if (attr->exclude_kernel)
> - config_base |= ARMV8_EXCLUDE_EL1;
> - if (!attr->exclude_hv)
> - config_base |= ARMV8_INCLUDE_EL2;
> + if (is_kernel_in_hyp_mode()) {
> + if (!attr->exclude_kernel || !attr->exclude_hv)
> + config_base |= ARMV8_INCLUDE_EL2;
Hmm, so if userspace sets exclude_kernel but not exclude_user and
exclude_hv, what should we do? I'm slightly tempted to reject the
filter with -EINVAL...
Will