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 Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id CF42DCD11C2 for ; Tue, 19 Mar 2024 15:24:00 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1rmbIt-0004lS-LR; Tue, 19 Mar 2024 11:23:03 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rmbIs-0004kh-Jl for qemu-devel@nongnu.org; Tue, 19 Mar 2024 11:23:02 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rmbIq-00017x-W0 for qemu-devel@nongnu.org; Tue, 19 Mar 2024 11:23:02 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1710861780; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:in-reply-to:in-reply-to: references:references; bh=AHYD2aoQDkkw9ORPXg1micmc/tT7gZ08fuyWCxxnQTY=; b=YzrIdz2VSFXihHylsaM3Ynf8OeDM/UYib+93VbRSpH4SFIu87z1vgvlbQ53EWTc/3EdVu6 w/wSQ+53oGjBYzWbvwWMGmALJZiC/ZKYcjynYBuVmnFtVNvyth/YPoIHmBV2DSRBxh+Axb XLXb+Q8CmfTTQOvSheImIuok9aG7KMY= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-148-P0s4xJHcMIqCeNA6JBZo5Q-1; Tue, 19 Mar 2024 11:22:56 -0400 X-MC-Unique: P0s4xJHcMIqCeNA6JBZo5Q-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.rdu2.redhat.com [10.11.54.7]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 72C92185A78E; Tue, 19 Mar 2024 15:22:56 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.88]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 692F51C060A4; Tue, 19 Mar 2024 15:22:54 +0000 (UTC) Date: Tue, 19 Mar 2024 15:22:47 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Shaoqin Huang Cc: qemu-arm@nongnu.org, Eric Auger , Sebastian Ott , Peter Maydell , Paolo Bonzini , qemu-devel@nongnu.org, kvm@vger.kernel.org Subject: Re: [PATCH v7] arm/kvm: Enable support for KVM_ARM_VCPU_PMU_V3_FILTER Message-ID: References: <20240221063431.76992-1-shahuang@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20240221063431.76992-1-shahuang@redhat.com> User-Agent: Mutt/2.2.12 (2023-09-09) X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.7 Received-SPF: pass client-ip=170.10.133.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -24 X-Spam_score: -2.5 X-Spam_bar: -- X-Spam_report: (-2.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.422, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Wed, Feb 21, 2024 at 01:34:31AM -0500, Shaoqin Huang wrote: > The KVM_ARM_VCPU_PMU_V3_FILTER provides the ability to let the VMM decide > which PMU events are provided to the guest. Add a new option > `kvm-pmu-filter` as -cpu sub-option to set the PMU Event Filtering. > Without the filter, all PMU events are exposed from host to guest by > default. The usage of the new sub-option can be found from the updated > document (docs/system/arm/cpu-features.rst). > > Here is an example which shows how to use the PMU Event Filtering, when > we launch a guest by use kvm, add such command line: > > # qemu-system-aarch64 \ > -accel kvm \ > -cpu host,kvm-pmu-filter="D:0x11-0x11" snip > @@ -517,6 +533,12 @@ void kvm_arm_add_vcpu_properties(ARMCPU *cpu) > kvm_steal_time_set); > object_property_set_description(obj, "kvm-steal-time", > "Set off to disable KVM steal time."); > + > + object_property_add_str(obj, "kvm-pmu-filter", kvm_pmu_filter_get, > + kvm_pmu_filter_set); > + object_property_set_description(obj, "kvm-pmu-filter", > + "PMU Event Filtering description for " > + "guest PMU. (default: NULL, disabled)"); > } Passing a string property, but....[1] > > bool kvm_arm_pmu_supported(void) > @@ -1706,6 +1728,62 @@ static bool kvm_arm_set_device_attr(ARMCPU *cpu, struct kvm_device_attr *attr, > return true; > } > > +static void kvm_arm_pmu_filter_init(ARMCPU *cpu) > +{ > + static bool pmu_filter_init; > + struct kvm_pmu_event_filter filter; > + struct kvm_device_attr attr = { > + .group = KVM_ARM_VCPU_PMU_V3_CTRL, > + .attr = KVM_ARM_VCPU_PMU_V3_FILTER, > + .addr = (uint64_t)&filter, > + }; > + int i; > + g_auto(GStrv) event_filters; > + > + if (!cpu->kvm_pmu_filter) { > + return; > + } > + if (kvm_vcpu_ioctl(CPU(cpu), KVM_HAS_DEVICE_ATTR, &attr)) { > + warn_report("The KVM doesn't support the PMU Event Filter!"); If the user requested a filter and it can't be supported, QEMU must exit with an error, not ignore the user's request. > + return; > + } > + > + /* > + * The filter only needs to be initialized through one vcpu ioctl and it > + * will affect all other vcpu in the vm. > + */ > + if (pmu_filter_init) { > + return; > + } else { > + pmu_filter_init = true; > + } > + > + event_filters = g_strsplit(cpu->kvm_pmu_filter, ";", -1); > + for (i = 0; event_filters[i]; i++) { > + unsigned short start = 0, end = 0; > + char act; > + > + if (sscanf(event_filters[i], "%c:%hx-%hx", &act, &start, &end) != 3) { > + warn_report("Skipping invalid PMU filter %s", event_filters[i]); > + continue; Warning on user syntax errors is undesirable - it should be a fatal error of the user gets this wrong. > + } > + > + if ((act != 'A' && act != 'D') || start > end) { > + warn_report("Skipping invalid PMU filter %s", event_filters[i]); > + continue; Likewise should be fatal. > + } > + > + filter.base_event = start; > + filter.nevents = end - start + 1; > + filter.action = (act == 'A') ? KVM_PMU_EVENT_ALLOW : > + KVM_PMU_EVENT_DENY; > + > + if (!kvm_arm_set_device_attr(cpu, &attr, "PMU_V3_FILTER")) { > + break; > + } > + } > +} ..[1] then implementing a custom parser is rather a QEMU design anti-pattern, especially when the proposed syntax is incapable of being mapped into the normal QAPI syntax for a list of structs should we want to fully convert -cpu to QAPI parsing later. I wonder if can we model this property with QAPI now ? With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|