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([2a01:e0a:59e:9d80:527b:9dff:feef:3874]) by smtp.gmail.com with ESMTPSA id c11-20020a0ce64b000000b0067ab7eada1dsm6177573qvn.59.2023.12.14.10.13.17 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 14 Dec 2023 10:13:19 -0800 (PST) Message-ID: Date: Thu, 14 Dec 2023 19:13:15 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4] arm/kvm: Enable support for KVM_ARM_VCPU_PMU_V3_FILTER Content-Language: en-US To: Shaoqin Huang , qemu-arm@nongnu.org Cc: Gavin Shan , Paolo Bonzini , Peter Maydell , kvm@vger.kernel.org, qemu-devel@nongnu.org References: <20231207103648.2925112-1-shahuang@redhat.com> From: Eric Auger In-Reply-To: <20231207103648.2925112-1-shahuang@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=170.10.129.124; envelope-from=eauger@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -5 X-Spam_score: -0.6 X-Spam_bar: / X-Spam_report: (-0.6 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, 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, RCVD_IN_SORBS_WEB=1.5, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=no 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: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Hi Shaoqin, On 12/7/23 11:36, Shaoqin Huang wrote: > The KVM_ARM_VCPU_PMU_V3_FILTER provide the ability to let the VMM decide > which PMU events are provided to the guest. Add a new option > `pmu-filter` as -accel sub-option to set the PMU Event Filtering. > Without the filter, the KVM will expose all events from the host to > guest by default. > > The `pmu-filter` has such format: > > pmu-filter="{A,D}:start-end[;{A,D}:start-end...]" > > The A means "allow" and D means "deny", start is the first event of the > range and the end is the last one. The first registered range defines > the global policy(global ALLOW if the first @action is DENY, global DENY > if the first @action is ALLOW). The start and end only support hex > format now. For example: > > pmu-filter="A:0x11-0x11;A:0x23-0x3a;D:0x30-0x30" > > Since the first action is allow, we have a global deny policy. It > will allow event 0x11 (The cycle counter), events 0x23 to 0x3a is > also allowed except the event 0x30 is denied, and all the other events > are disallowed. > > Here is an real example 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,pmu-filter="D:0x11-0x11" > > Since the first action is deny, we have a global allow policy. This > disables the filtering of the cycle counter (event 0x11 being CPU_CYCLES). > > And then in guest, use the perf to count the cycle: > > # perf stat sleep 1 > > Performance counter stats for 'sleep 1': > > 1.22 msec task-clock # 0.001 CPUs utilized > 1 context-switches # 820.695 /sec > 0 cpu-migrations # 0.000 /sec > 55 page-faults # 45.138 K/sec > cycles > 1128954 instructions > 227031 branches # 186.323 M/sec > 8686 branch-misses # 3.83% of all branches > > 1.002492480 seconds time elapsed > > 0.001752000 seconds user > 0.000000000 seconds sys > > As we can see, the cycle counter has been disabled in the guest, but > other pmu events are still work. > > Signed-off-by: Shaoqin Huang > --- > v3->v4: > - Fix the wrong check for pmu_filter_init. [Sebastian] > - Fix multiple alignment issue. [Gavin] > - Report error by warn_report() instead of error_report(), and don't use > abort() since the PMU Event Filter is an add-on and best-effort feature. > [Gavin] > - Add several missing { } for single line of code. [Gavin] > - Use the g_strsplit() to replace strtok(). [Gavin] > > v2->v3: > - Improve commits message, use kernel doc wording, add more explaination on > filter example, fix some typo error. [Eric] > - Add g_free() in kvm_arch_set_pmu_filter() to prevent memory leak. [Eric] > - Add more precise error message report. [Eric] > - In options doc, add pmu-filter rely on KVM_ARM_VCPU_PMU_V3_FILTER support in > KVM. [Eric] > > v1->v2: > - Add more description for allow and deny meaning in > commit message. [Sebastian] > - Small improvement. [Sebastian] > > v2: https://lore.kernel.org/all/20231117060838.39723-1-shahuang@redhat.com/ > v1: https://lore.kernel.org/all/20231113081713.153615-1-shahuang@redhat.com/ > --- > include/sysemu/kvm_int.h | 1 + > qemu-options.hx | 21 +++++++++++ > target/arm/kvm.c | 23 ++++++++++++ > target/arm/kvm64.c | 75 ++++++++++++++++++++++++++++++++++++++++ > 4 files changed, 120 insertions(+) > > diff --git a/include/sysemu/kvm_int.h b/include/sysemu/kvm_int.h > index fd846394be..8f4601474f 100644 > --- a/include/sysemu/kvm_int.h > +++ b/include/sysemu/kvm_int.h > @@ -120,6 +120,7 @@ struct KVMState > uint32_t xen_caps; > uint16_t xen_gnttab_max_frames; > uint16_t xen_evtchn_max_pirq; > + char *kvm_pmu_filter; > }; > > void kvm_memory_listener_register(KVMState *s, KVMMemoryListener *kml, > diff --git a/qemu-options.hx b/qemu-options.hx > index 42fd09e4de..054865ba0d 100644 > --- a/qemu-options.hx > +++ b/qemu-options.hx > @@ -187,6 +187,7 @@ DEF("accel", HAS_ARG, QEMU_OPTION_accel, > " tb-size=n (TCG translation block cache size)\n" > " dirty-ring-size=n (KVM dirty ring GFN count, default 0)\n" > " eager-split-size=n (KVM Eager Page Split chunk size, default 0, disabled. ARM only)\n" > + " pmu-filter={A,D}:start-end[;{A,D}:start-end...] (KVM PMU Event Filter, default no filter. ARM only)\n" Sorry for coming back late with this kind of comment but I am not comfortable with the pmu-filter being an accel suboption. Why isn't it a cpu option instead like the pmu option? qemu-system-aarch64 -M virt -cpu max,pmu-filter="A:0x11-0x11;A:0x23-0x3a;D:0x30-0x30",sve=on,sve128=on,sve256=on See https://qemu-project.gitlab.io/qemu/system/arm/cpu-features.html Wouldn't it make more sense? The PMU filter control is a vcpu device ctrl, isn't it. > " notify-vmexit=run|internal-error|disable,notify-window=n (enable notify VM exit and set notify window, x86 only)\n" > " thread=single|multi (enable multi-threaded TCG)\n", QEMU_ARCH_ALL) > SRST > @@ -259,6 +260,26 @@ SRST > impact on the memory. By default, this feature is disabled > (eager-split-size=0). > > + ``pmu-filter={A,D}:start-end[;{A,D}:start-end...]`` > + KVM implements PMU Event Filtering to prevent a guest from being able to > + sample certain events. It depends on the KVM_ARM_VCPU_PMU_V3_FILTER > + attribute supported in KVM. It has the following format: > + > + pmu-filter="{A,D}:start-end[;{A,D}:start-end...]" > + > + The A means "allow" and D means "deny", start is the first event of the > + range and the end is the last one. The first registered range defines > + the global policy(global ALLOW if the first @action is DENY, global DENY > + if the first @action is ALLOW). The start and end only support hex > + format now. For example: > + > + pmu-filter="A:0x11-0x11;A:0x23-0x3a;D:0x30-0x30" > + > + Since the first action is allow, we have a global deny policy. It > + will allow event 0x11 (The cycle counter), events 0x23 to 0x3a is > + also allowed except the event 0x30 is denied, and all the other events > + are disallowed. > + > ``notify-vmexit=run|internal-error|disable,notify-window=n`` > Enables or disables notify VM exit support on x86 host and specify > the corresponding notify window to trigger the VM exit if enabled. > diff --git a/target/arm/kvm.c b/target/arm/kvm.c > index 7903e2ddde..1f73b83674 100644 > --- a/target/arm/kvm.c > +++ b/target/arm/kvm.c > @@ -1108,6 +1108,22 @@ static void kvm_arch_set_eager_split_size(Object *obj, Visitor *v, > s->kvm_eager_split_size = value; > } > > +static char *kvm_arch_get_pmu_filter(Object *obj, Error **errp) > +{ > + KVMState *s = KVM_STATE(obj); > + > + return g_strdup(s->kvm_pmu_filter); > +} > + > +static void kvm_arch_set_pmu_filter(Object *obj, const char *pmu_filter, > + Error **errp) > +{ > + KVMState *s = KVM_STATE(obj); > + > + g_free(s->kvm_pmu_filter); > + s->kvm_pmu_filter = g_strdup(pmu_filter); > +} > + > void kvm_arch_accel_class_init(ObjectClass *oc) > { > object_class_property_add(oc, "eager-split-size", "size", > @@ -1116,4 +1132,11 @@ void kvm_arch_accel_class_init(ObjectClass *oc) > > object_class_property_set_description(oc, "eager-split-size", > "Eager Page Split chunk size for hugepages. (default: 0, disabled)"); > + > + object_class_property_add_str(oc, "pmu-filter", > + kvm_arch_get_pmu_filter, > + kvm_arch_set_pmu_filter); > + > + object_class_property_set_description(oc, "pmu-filter", > + "PMU Event Filtering description for guest PMU. (default: NULL, disabled)"); > } > diff --git a/target/arm/kvm64.c b/target/arm/kvm64.c > index 3c175c93a7..0ed6744057 100644 > --- a/target/arm/kvm64.c > +++ b/target/arm/kvm64.c > @@ -10,6 +10,7 @@ > */ > > #include "qemu/osdep.h" > +#include > #include > #include > > @@ -131,6 +132,77 @@ static bool kvm_arm_set_device_attr(CPUState *cs, struct kvm_device_attr *attr, > return true; > } > > +static void kvm_arm_pmu_filter_init(CPUState *cs) > +{ > + KVMState *kvm_state = cs->kvm_state; > + static bool pmu_filter_init = false; > + 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, > + }; > + char act; > + int i; > + gchar **event_filters; > + > + if (!kvm_state->kvm_pmu_filter) > + return; > + > + if (kvm_vcpu_ioctl(cs, KVM_HAS_DEVICE_ATTR, &attr)) { > + warn_report("The kernel doesn't support the PMU Event Filter!\n"); > + return; > + } > + > + /* The filter only needs to be initialized for 1 vcpu. */ Are you sure? This is a per vcpu device ctrl. Where is it written in the doc that this shall not be called for each vcpu > + if (pmu_filter_init) { > + return; > + } > + pmu_filter_init = true; > + > + event_filters = g_strsplit(kvm_state->kvm_pmu_filter, ";", -1); > + > + for (i = 0; event_filters[i]; i++) { > + unsigned short start = 0, end = 0; > + > + sscanf(event_filters[i], "%c:%hx-%hx", &act, &start, &end); > + if ((act != 'A' && act != 'D') || (!start && !end)) { > + warn_report("Skipping invalid PMU filter %s\n", event_filters[i]); > + continue; > + } > + > + filter = (struct kvm_pmu_event_filter) { > + .base_event = start, > + .nevents = end - start + 1, > + .action = act == 'A' ? KVM_PMU_EVENT_ALLOW : > + KVM_PMU_EVENT_DENY, > + }; > + > + if (!kvm_arm_set_device_attr(cs, &attr, "PMU Event Filter")) { > + if (errno == EINVAL) { > + warn_report("Invalid PMU filter range [0x%x-0x%x]. " > + "ARMv8.0 support 10 bits event space, " > + "ARMv8.1 support 16 bits event space", > + start, end); > + } > + else if (errno == ENODEV) { > + warn_report("GIC not initialized"); > + } > + else if (errno == ENXIO) { > + warn_report("PMUv3 not properly configured or in-kernel irqchip " > + "not configured."); > + } > + else if (errno == EBUSY) { > + warn_report("PMUv3 already initialized or a VCPU has already run"); > + } > + > + break; > + } > + } > + > + g_strfreev(event_filters); > +} > + > void kvm_arm_pmu_init(CPUState *cs) > { > struct kvm_device_attr attr = { > @@ -141,6 +213,9 @@ void kvm_arm_pmu_init(CPUState *cs) > if (!ARM_CPU(cs)->has_pmu) { > return; > } > + > + kvm_arm_pmu_filter_init(cs); > + > if (!kvm_arm_set_device_attr(cs, &attr, "PMU")) { > error_report("failed to init PMU"); > abort(); Thanks Eric