From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DCE36C43387 for ; Tue, 8 Jan 2019 10:18:55 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id AD0AD2087F for ; Tue, 8 Jan 2019 10:18:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="W9ePKXz8" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AD0AD2087F Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=o/qyyhsuv5tiR7m3qOnQeepwarisljwyY6Sz5sWPx4M=; b=W9ePKXz8nfIExQ 7tTXBr2tJETk/7SJoD0AwgoYaXY7ETV2wxlmqLxmc/Uy0UNdFtR4ijNSxv9LaYcyiG+2AXGwr84z5 eJwPaEL2Da1YWoNvlwcn8/Bz7qjNXLvZqaLOihJV7cpV4Cor9iGicG9kIUx1GdF54JA8Y2JptFnRs qsoQUr8p8YLoYZvk3F2JjPnoUVSUyFAZwQZRqUzoECsDFl7QWXo+l367sK9L2LhA/+LRyDzx++fFd CgHwQXpnLK9/BbNYFp2NJ9vksOX3xg3uLP0ZIDfWx/06dAx8Gy5WI9uWdt+obk/YQ264ioafyLzVV hV8NaEM6XkJI3A09NYsw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1ggoTD-0004n4-Ul; Tue, 08 Jan 2019 10:18:51 +0000 Received: from foss.arm.com ([217.140.101.70]) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1ggoTA-0004mT-CV for linux-arm-kernel@lists.infradead.org; Tue, 08 Jan 2019 10:18:50 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id F1047EBD; Tue, 8 Jan 2019 02:18:45 -0800 (PST) Received: from localhost (e113682-lin.copenhagen.arm.com [10.32.144.41]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 86EEE3F6CF; Tue, 8 Jan 2019 02:18:45 -0800 (PST) Date: Tue, 8 Jan 2019 11:18:43 +0100 From: Christoffer Dall To: Will Deacon Subject: Re: [PATCH v8 4/5] arm64: arm_pmu: Add support for exclude_host/exclude_guest attributes Message-ID: <20190108101843.GH10769@e113682-lin.lund.arm.com> References: <1544610573-28446-1-git-send-email-andrew.murray@arm.com> <1544610573-28446-5-git-send-email-andrew.murray@arm.com> <20181218120226.GC25383@e113682-lin.lund.arm.com> <20190104153205.GA31479@edgewater-inn.cambridge.arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190104153205.GA31479@edgewater-inn.cambridge.arm.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190108_021848_437964_F7B01D7F X-CRM114-Status: GOOD ( 28.58 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Julien Thierry , Marc Zyngier , Catalin Marinas , joro@8bytes.org, Suzuki K Poulose , Andrew Murray , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Jan 04, 2019 at 03:32:06PM +0000, Will Deacon wrote: > On Tue, Dec 18, 2018 at 01:02:26PM +0100, Christoffer Dall wrote: > > On Wed, Dec 12, 2018 at 10:29:32AM +0000, Andrew Murray wrote: > > > Add support for the :G and :H attributes in perf by handling the > > > exclude_host/exclude_guest event attributes. > > > > > > We notify KVM of counters that we wish to be enabled or disabled on > > > guest entry/exit and thus defer from starting or stopping :G events > > > as per the events exclude_host attribute. > > > > > > With both VHE and non-VHE we switch the counters between host/guest > > > at EL2. We are able to eliminate counters counting host events on > > > the boundaries of guest entry/exit when using :G by filtering out > > > EL2 for exclude_host. 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 > > > --- > > > arch/arm64/kernel/perf_event.c | 51 ++++++++++++++++++++++++++++++++++++------ > > > 1 file changed, 44 insertions(+), 7 deletions(-) > > > > > > diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c > > > index de564ae..4a3c73d 100644 > > > --- a/arch/arm64/kernel/perf_event.c > > > +++ b/arch/arm64/kernel/perf_event.c > > > @@ -26,6 +26,7 @@ > > > > > > #include > > > #include > > > +#include > > > #include > > > #include > > > #include > > > @@ -647,11 +648,26 @@ static inline int armv8pmu_enable_counter(int idx) > > > > > > static inline void armv8pmu_enable_event_counter(struct perf_event *event) > > > { > > > + struct perf_event_attr *attr = &event->attr; > > > int idx = event->hw.idx; > > > + int flags = 0; > > > + u32 counter_bits = BIT(ARMV8_IDX_TO_COUNTER(idx)); > > > > > > - armv8pmu_enable_counter(idx); > > > if (armv8pmu_event_is_chained(event)) > > > - armv8pmu_enable_counter(idx - 1); > > > + counter_bits |= BIT(ARMV8_IDX_TO_COUNTER(idx - 1)); > > > + > > > + if (!attr->exclude_host) > > > + flags |= KVM_PMU_EVENTS_HOST; > > > + if (!attr->exclude_guest) > > > + flags |= KVM_PMU_EVENTS_GUEST; > > > + > > > + kvm_set_pmu_events(counter_bits, flags); > > > + > > > + if (!attr->exclude_host) { > > > + armv8pmu_enable_counter(idx); > > > + if (armv8pmu_event_is_chained(event)) > > > + armv8pmu_enable_counter(idx - 1); > > > + } > > > } > > > > > > static inline int armv8pmu_disable_counter(int idx) > > > @@ -664,11 +680,20 @@ static inline int armv8pmu_disable_counter(int idx) > > > static inline void armv8pmu_disable_event_counter(struct perf_event *event) > > > { > > > struct hw_perf_event *hwc = &event->hw; > > > + struct perf_event_attr *attr = &event->attr; > > > int idx = hwc->idx; > > > + u32 counter_bits = BIT(ARMV8_IDX_TO_COUNTER(idx)); > > > > > > if (armv8pmu_event_is_chained(event)) > > > - armv8pmu_disable_counter(idx - 1); > > > - armv8pmu_disable_counter(idx); > > > + counter_bits |= BIT(ARMV8_IDX_TO_COUNTER(idx - 1)); > > > + > > > + kvm_clr_pmu_events(counter_bits); > > > + > > > + if (!attr->exclude_host) { > > > + if (armv8pmu_event_is_chained(event)) > > > + armv8pmu_disable_counter(idx - 1); > > > + armv8pmu_disable_counter(idx); > > > + } > > > } > > > > > > static inline int armv8pmu_enable_intens(int idx) > > > @@ -943,16 +968,25 @@ static int armv8pmu_set_event_filter(struct hw_perf_event *event, > > > * Therefore we ignore exclude_hv in this configuration, since > > > * there's no hypervisor to sample anyway. This is consistent > > > * with other architectures (x86 and Power). > > > + * > > > + * To eliminate counting host events on the boundaries of > > > + * guest entry/exit we ensure EL2 is not included in hyp mode > > > + * with !exclude_host. > > > */ > > > if (is_kernel_in_hyp_mode()) { > > > - if (!attr->exclude_kernel) > > > + if (!attr->exclude_kernel && !attr->exclude_host) > > > config_base |= ARMV8_PMU_INCLUDE_EL2; > > > } else { > > > - if (attr->exclude_kernel) > > > - config_base |= ARMV8_PMU_EXCLUDE_EL1; > > > if (!attr->exclude_hv) > > > config_base |= ARMV8_PMU_INCLUDE_EL2; > > > > I'm not sure about the current use of exclude_hv here. The comment says > > it's consistent with other architectures, but I can't find an example to > > confirm this, and I don't think we have a comparable thing to the split > > of the hypervisor between EL1 and EL2 we have on non-VHE. > > FWIW, that comment came from this thread: > > http://lists.infradead.org/pipermail/linux-arm-kernel/2017-April/503908.html > > That was painful enough at the time, so I'd /really/ prefer not to change > the semantics of this again if we can avoid it. The comment makes sense for the is_kernel_in_hyp_mode() case. However, for the !is_kernel_in_hyp_mode() case I can't see the current behavior of exclude_hv being similar in other architectures. I don't think the current semantics of excluding EL2 on a non-VHE host system makes much sense, and I doubt anyone is using that for something meaningful. I think changing behavior for excldue_hv to depend on is_hyp_mode_available rather than is_kernel_in_hyp_mode is the right thing to do which would also align the semantics with other architectures and between VHE and non-VHE. Thanks, Christoffer _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel