On Mon, Feb 15, 2016 at 06:23:35PM +0000, Marc Zyngier wrote: > On 15/02/16 17:22, Will Deacon wrote: > > 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 <[email protected]> > >> Acked-by: Catalin Marinas <[email protected]> > >> Signed-off-by: Marc Zyngier <[email protected]> > >> --- > >> 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... > > I was angling for the minimum level of surprise for the user, but > I guess that the results are going to be troubling anyway. > > How about something like this on top: > > diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c > index 6013a38..8c00ed4 100644 > --- a/arch/arm64/kernel/perf_event.c > +++ b/arch/arm64/kernel/perf_event.c > @@ -695,7 +695,10 @@ static int armv8pmu_set_event_filter(struct > hw_perf_event *event, > if (attr->exclude_user) > config_base |= ARMV8_EXCLUDE_EL0; > if (is_kernel_in_hyp_mode()) { > - if (!attr->exclude_kernel || !attr->exclude_hv) > + /* Demand that kernel and hv are consistent */ > + if (attr->exclude_kernel != attr->exclude_hv) > + return -EINVAL; > + if (!attr->exclude_hv) > config_base |= ARMV8_INCLUDE_EL2; > } else { > if (attr->exclude_kernel)
Looks like the right idea, and you can probably refactor things slightly to avoid having two codepaths dealing with ARMV8_INCLUDE_EL2. Note that I've got a couple of outstanding questions with the architects that I should have answers to later in the week. Will
