From: Suzuki K Poulose <suzuki.poulose@arm.com> To: Andrew Murray <andrew.murray@arm.com>, Christoffer Dall <christoffer.dall@arm.com>, Marc Zyngier <marc.zyngier@arm.com>, Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will.deacon@arm.com>, Mark Rutland <mark.rutland@arm.com> Cc: kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH 3/4] arm64: arm_pmu: Exclude EL1,2 with :G :H perf attributes Date: Thu, 15 Nov 2018 14:57:59 +0000 [thread overview] Message-ID: <2b4efe9a-4f2b-961f-c841-6378dbb4bbd3@arm.com> (raw) In-Reply-To: <1542286549-4501-4-git-send-email-andrew.murray@arm.com> Hi Andrew, On 15/11/2018 12:55, Andrew Murray wrote: > When using VHE, EL1 is unused by the host and EL2 is unused by the > guest - therefore we can filter out these events with the PMU as per > the 'exclude_host' and 'exclude_guest' attributes. > > With both VHE and non-VHE we switch the counters between host/guest > at EL2. With non-VHE when using 'exclude_host' we filter out EL2. > > These changes eliminate counters counting host events on the > boundaries of guest entry/exit when using :G. However when using :H > unless exclude_hv is set on non-VHE then there is a small blackout > window at the guest entry/exit where host events are not captured. > > Signed-off-by: Andrew Murray <andrew.murray@arm.com> > --- > arch/arm64/kernel/perf_event.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c > index 89d444f..c079c1f 100644 > --- a/arch/arm64/kernel/perf_event.c > +++ b/arch/arm64/kernel/perf_event.c > @@ -971,12 +971,14 @@ static int armv8pmu_set_event_filter(struct hw_perf_event *event, > * with other architectures (x86 and Power). > */ > if (is_kernel_in_hyp_mode()) { > - if (!attr->exclude_kernel) > + if (!attr->exclude_kernel && !attr->exclude_host) > config_base |= ARMV8_PMU_INCLUDE_EL2; > + if (attr->exclude_guest) > + config_base |= ARMV8_PMU_EXCLUDE_EL1; Do we really need this ? exclude_guest also implies you need to exclude guest EL0. We anyway disable the events when we enter the guest. So the above is not necessary and could possibly create confusion. > } else { > if (attr->exclude_kernel) > config_base |= ARMV8_PMU_EXCLUDE_EL1; > - if (!attr->exclude_hv) > + if (!attr->exclude_hv && !attr->exclude_host) > config_base |= ARMV8_PMU_INCLUDE_EL2; > } > if (attr->exclude_user) > I think this can be folded into the previous patch, which adds the support for exclude_host/guest support. :G, :H are nothing but the those exclude_ flags. Otherwise looks good to me. Cheers Suzuki
WARNING: multiple messages have this Message-ID (diff)
From: suzuki.poulose@arm.com (Suzuki K Poulose) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH 3/4] arm64: arm_pmu: Exclude EL1,2 with :G :H perf attributes Date: Thu, 15 Nov 2018 14:57:59 +0000 [thread overview] Message-ID: <2b4efe9a-4f2b-961f-c841-6378dbb4bbd3@arm.com> (raw) In-Reply-To: <1542286549-4501-4-git-send-email-andrew.murray@arm.com> Hi Andrew, On 15/11/2018 12:55, Andrew Murray wrote: > When using VHE, EL1 is unused by the host and EL2 is unused by the > guest - therefore we can filter out these events with the PMU as per > the 'exclude_host' and 'exclude_guest' attributes. > > With both VHE and non-VHE we switch the counters between host/guest > at EL2. With non-VHE when using 'exclude_host' we filter out EL2. > > These changes eliminate counters counting host events on the > boundaries of guest entry/exit when using :G. However when using :H > unless exclude_hv is set on non-VHE then there is a small blackout > window at the guest entry/exit where host events are not captured. > > Signed-off-by: Andrew Murray <andrew.murray@arm.com> > --- > arch/arm64/kernel/perf_event.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c > index 89d444f..c079c1f 100644 > --- a/arch/arm64/kernel/perf_event.c > +++ b/arch/arm64/kernel/perf_event.c > @@ -971,12 +971,14 @@ static int armv8pmu_set_event_filter(struct hw_perf_event *event, > * with other architectures (x86 and Power). > */ > if (is_kernel_in_hyp_mode()) { > - if (!attr->exclude_kernel) > + if (!attr->exclude_kernel && !attr->exclude_host) > config_base |= ARMV8_PMU_INCLUDE_EL2; > + if (attr->exclude_guest) > + config_base |= ARMV8_PMU_EXCLUDE_EL1; Do we really need this ? exclude_guest also implies you need to exclude guest EL0. We anyway disable the events when we enter the guest. So the above is not necessary and could possibly create confusion. > } else { > if (attr->exclude_kernel) > config_base |= ARMV8_PMU_EXCLUDE_EL1; > - if (!attr->exclude_hv) > + if (!attr->exclude_hv && !attr->exclude_host) > config_base |= ARMV8_PMU_INCLUDE_EL2; > } > if (attr->exclude_user) > I think this can be folded into the previous patch, which adds the support for exclude_host/guest support. :G, :H are nothing but the those exclude_ flags. Otherwise looks good to me. Cheers Suzuki
next prev parent reply other threads:[~2018-11-15 14:58 UTC|newest] Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-11-15 12:55 [PATCH 0/4] arm64: Support perf event modifiers :G and :H Andrew Murray 2018-11-15 12:55 ` Andrew Murray 2018-11-15 12:55 ` [PATCH 1/4] arm64: KVM: add accessors to track guest/host only counters Andrew Murray 2018-11-15 12:55 ` Andrew Murray 2018-11-15 12:55 ` [PATCH 2/4] arm64: arm_pmu: Add support for exclude_host/exclude_guest attributes Andrew Murray 2018-11-15 12:55 ` Andrew Murray 2018-11-15 12:55 ` [PATCH 3/4] arm64: arm_pmu: Exclude EL1,2 with :G :H perf attributes Andrew Murray 2018-11-15 12:55 ` Andrew Murray 2018-11-15 14:57 ` Suzuki K Poulose [this message] 2018-11-15 14:57 ` Suzuki K Poulose 2018-11-15 16:06 ` Andrew Murray 2018-11-15 16:06 ` Andrew Murray 2018-11-15 12:55 ` [PATCH 4/4] arm64: KVM: Enable support for :G/:H perf event modifiers Andrew Murray 2018-11-15 12:55 ` Andrew Murray 2018-11-15 14:00 ` Julien Thierry 2018-11-15 14:00 ` Julien Thierry 2018-11-15 15:57 ` Andrew Murray 2018-11-15 15:57 ` Andrew Murray 2018-11-15 17:40 ` Suzuki K Poulose 2018-11-15 17:40 ` Suzuki K Poulose 2018-11-16 12:12 ` Andrew Murray 2018-11-16 12:12 ` Andrew Murray 2018-11-16 17:53 ` Suzuki K Poulose 2018-11-16 17:53 ` Suzuki K Poulose
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