Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1432313AbdDYQxJ (ORCPT ); Tue, 25 Apr 2017 12:53:09 -0400 Received: from foss.arm.com ([217.140.101.70]:44654 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1432297AbdDYQxB (ORCPT ); Tue, 25 Apr 2017 12:53:01 -0400 Date: Tue, 25 Apr 2017 17:53:00 +0100 From: Will Deacon To: Ganapatrao Kulkarni Cc: Mark Rutland , "Andrew.Pinski@caviumnetworks.com" , Ganapatrao Kulkarni , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , Catalin Marinas , acme@kernel.org, alexander.shishkin@linux.intel.com, peterz@infradead.org, Ingo Molnar , jnair@caviumnetworks.com Subject: Re: [PATCH v2] arm64: perf: Use only exclude_kernel attribute when kernel is running in HYP Message-ID: <20170425165259.GS24484@arm.com> References: <1492623846-29335-1-git-send-email-ganapatrao.kulkarni@cavium.com> <20170420084928.GC31436@leverpostej> <20170424154530.GO12323@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3140 Lines: 68 On Tue, Apr 25, 2017 at 09:13:40AM +0530, Ganapatrao Kulkarni wrote: > On Mon, Apr 24, 2017 at 9:15 PM, Will Deacon wrote: > > On Thu, Apr 20, 2017 at 02:56:50PM +0530, Ganapatrao Kulkarni wrote: > >> On Thu, Apr 20, 2017 at 2:19 PM, Mark Rutland wrote: > >> > On Wed, Apr 19, 2017 at 11:14:06PM +0530, Ganapatrao Kulkarni wrote: > >> >> commit d98ecda (arm64: perf: Count EL2 events if the kernel is running in HYP) > >> >> is returning error for perf syscall with mixed attribute set for exclude_kernel > >> >> and exclude_hv. This change is breaking some applications (observed with hhvm) > >> >> when ran on VHE enabled platforms. > >> >> > >> >> Adding fix to consider only exclude_kernel attribute when kernel is > >> >> running in HYP. Also adding sysfs file to notify the bhehaviour > >> >> of attribute exclude_hv. > >> >> > >> >> Signed-off-by: Ganapatrao Kulkarni > >> >> --- > >> >> > >> >> Changelog: > >> >> > >> >> V2: > >> >> - Changes as per Will Deacon's suggestion. > >> >> > >> >> V1: Initial patch > >> >> > >> >> arch/arm64/kernel/perf_event.c | 28 ++++++++++++++++++++++++---- > >> >> include/linux/perf/arm_pmu.h | 1 + > >> >> 2 files changed, 25 insertions(+), 4 deletions(-) > >> >> > >> >> @@ -871,14 +890,13 @@ static int armv8pmu_set_event_filter(struct hw_perf_event *event, > >> >> > >> >> if (attr->exclude_idle) > >> >> return -EPERM; > >> >> - if (is_kernel_in_hyp_mode() && > >> >> - attr->exclude_kernel != attr->exclude_hv) > >> >> - return -EINVAL; > >> >> + if (is_kernel_in_hyp_mode() && !attr->exclude_kernel) > >> >> + config_base |= ARMV8_PMU_INCLUDE_EL2; > >> >> if (attr->exclude_user) > >> >> config_base |= ARMV8_PMU_EXCLUDE_EL0; > >> >> if (!is_kernel_in_hyp_mode() && attr->exclude_kernel) > >> >> config_base |= ARMV8_PMU_EXCLUDE_EL1; > >> >> - if (!attr->exclude_hv) > >> >> + if (!is_kernel_in_hyp_mode() && !attr->exclude_hv) > >> >> config_base |= ARMV8_PMU_INCLUDE_EL2; > >> > > >> > This isn't quite what Will suggested. > >> > > >> > The idea was that userspace would read sysfs, then use that to determine > >> > the correct exclusion parameters [1,2]. This logic was not expected to > >> > change; it correctly validates whether we can provide what the user > >> > requests. > >> > >> OK, if you are ok with sysfs part, i can send next version with that > >> change only?. > > > > I think the sysfs part is still a little dodgy, since you still expose the > > "exclude_hv" file with a value of 0 when not running at EL2, which would > > imply that exclude_hv is forced to zero. I don't think that's correct. > > okay, i can make exclude_hv visible only when kernel booted in EL2. > is it ok to have empty directory "attr" when kernel booted to EL1? > attr can be place holder for any other miscellaneous attributes, that > can be added in future. Sounds good to me, although I'll seek comment from the other perf folks before merging anything with ABI implications. Will