From patchwork Thu Sep 19 19:07:50 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Colton Lewis X-Patchwork-Id: 13807966 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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id B0DE1CF3962 for ; Thu, 19 Sep 2024 19:15:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Type:Cc:To:From: Subject:Message-ID:References:Mime-Version:In-Reply-To:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=09zZtsyjNKU34RxIAdYq19fo4EG569yh76FDw7B839k=; b=V/f6Vn6nS9Q0wvy99dsZwp0hnG xdctzARc5XU+nf7MIf9ZJG7PTJ+hZoOS7QzxXjJt8XX1qTjcO8qq2Gybnd1jTxbEjkCudMhHbB0iU eRBh3HEHM5QKtGFKC/Dwyb7pcz354CUVgZIf3JMyRRnQv+JcUiuRaoIuNGkYVGAg9Y1xIRELy0ifh 5SD/s3Jy67iifoPXeCDYsJPg07agXWPwAcs3ioKh6mqxoj5QvdNNbBW1ekbs+LXapgMGUAT4mCGXl hazXN20QnkbYYgpeev5sOcdA1cRUFuMfWJEejc9DDge3sDNjPmWKDR21lBLH/y1FFh+3VJCO48OcR r5wXXH7w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1srMcU-0000000Atp6-39vu; Thu, 19 Sep 2024 19:15:14 +0000 Received: from mail-yb1-xb49.google.com ([2607:f8b0:4864:20::b49]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1srMVf-0000000AskM-0v67 for linux-arm-kernel@lists.infradead.org; Thu, 19 Sep 2024 19:08:12 +0000 Received: by mail-yb1-xb49.google.com with SMTP id 3f1490d57ef6-e1dc0585fbfso1887724276.3 for ; Thu, 19 Sep 2024 12:08:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1726772889; x=1727377689; darn=lists.infradead.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=09zZtsyjNKU34RxIAdYq19fo4EG569yh76FDw7B839k=; b=GHGIB1R3ZPIut962NQgmkBs6gPvuaeBhxpetdR6oqcfzwg6lZM8yP5kWRRZLrJRTJD wK/Ydj1dbGr+WODcUqpN1HWuSP+Q4x64QN/e0Grr1Q/hnv1sOzH9/s01/y9m0qj3N8Sn DAshbPm7xoqDasnKZfuAUSh07JnDWTxNyP/N2U6fAaPM9Whg5CDvOw19NTT0vLuT20Bv ndqMb4OBzQZRO2RFgQL3LyxfUoT2UuJPXHb9EnUlKouGn83zH3L2z6GuPGMRKNOh+0wi 22pTraKiD+YxSQWWuAyvCDR6yuMW3oc+cqAXpXGAUtbB41MJe1U9JiNGZHaQMGafXsDj PiTg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1726772889; x=1727377689; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=09zZtsyjNKU34RxIAdYq19fo4EG569yh76FDw7B839k=; b=VJqIY4m9yyq6D6Z3pwZYnYEfhyMHBssqumBmfoPoEq3nMK3IbWyJ53HJN4VrwWnKht Ktuq2RInWaDuAj3pRVuO/+ZH6mFp7RExKfg4u/cNw+lM8PH5mV/Spp5uduhHeYT5vcRc j5qcCXnhBQYAQXMKv+SMZ78gQy/LHtSjIXcgIZ0snx0NOQqf6CjkgHFgfR7gGZLPSO/a zV9Oq0ucp9wiaXb36Iv848etGVMQ4WhOp39+Org9VLKxYn11g90skXr6sUaBCDRqScuQ kQz8ht6oXkJWtc7FSExRcIc+C/727vSgFA9IKF1tLIGENhVoQPcX8w9Md646ZEKv4b6p uRKg== X-Forwarded-Encrypted: i=1; AJvYcCWVDLV4PR9arwGWqGR48QUAKfOd8cc6xVTZJp0vbDLY5xs2/1n3KhntBurt0pDCzPI3GrZln3m9quE3Yrx0y/Gl@lists.infradead.org X-Gm-Message-State: AOJu0YwZZxueo2XJPwh5PUqvIzN66z+G9gFpR16FXCn/mdL4cKpLd+2W YVYxDwC4TZplvnaHMaypKWdPAR4Mct30jzbUw6PoX5ZIpJBAVx8PaQXRqSrFNX2pRzN54fZUvF9 nHhZKe51XQfIgMGugUj50xQ== X-Google-Smtp-Source: AGHT+IH7DS+SKBUjwFhvlyrXRx7BdcWzXxigrbQzKIYP4oeDJso13ZKWEUISE2cE3y2zWZHTyZIEgxGF1DgagD7KPQ== X-Received: from coltonlewis-kvm.c.googlers.com ([fda3:e722:ac3:cc00:11b:3898:ac11:fa18]) (user=coltonlewis job=sendgmr) by 2002:a05:6902:1347:b0:e0b:958a:3344 with SMTP id 3f1490d57ef6-e2250cd2f53mr3552276.10.1726772889473; Thu, 19 Sep 2024 12:08:09 -0700 (PDT) Date: Thu, 19 Sep 2024 19:07:50 +0000 In-Reply-To: <20240919190750.4163977-1-coltonlewis@google.com> Mime-Version: 1.0 References: <20240919190750.4163977-1-coltonlewis@google.com> X-Mailer: git-send-email 2.46.0.792.g87dc391469-goog Message-ID: <20240919190750.4163977-6-coltonlewis@google.com> Subject: [PATCH v4 5/5] perf: Correct perf sampling with guest VMs From: Colton Lewis To: kvm@vger.kernel.org Cc: Oliver Upton , Sean Christopherson , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , Kan Liang , Will Deacon , Russell King , Catalin Marinas , Michael Ellerman , Nicholas Piggin , Christophe Leroy , Naveen N Rao , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , Thomas Gleixner , Borislav Petkov , Dave Hansen , x86@kernel.org, "H . Peter Anvin" , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, Colton Lewis X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240919_120811_311173_4D4A52B5 X-CRM114-Status: GOOD ( 21.81 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Previously any PMU overflow interrupt that fired while a VCPU was loaded was recorded as a guest event whether it truly was or not. This resulted in nonsense perf recordings that did not honor perf_event_attr.exclude_guest and recorded guest IPs where it should have recorded host IPs. Rework the sampling logic to only record guest samples for events with exclude_guest = 0. This way any host-only events with exclude_guest set will never see unexpected guest samples. The behaviour of events with exclude_guest = 0 is unchanged. Note that events configured to sample both host and guest may still misattribute a PMI that arrived in the host as a guest event depending on KVM arch and vendor behavior. Signed-off-by: Colton Lewis --- arch/arm64/include/asm/perf_event.h | 4 ---- arch/arm64/kernel/perf_callchain.c | 28 ---------------------------- arch/x86/events/core.c | 16 ++++------------ include/linux/perf_event.h | 21 +++++++++++++++++++-- kernel/events/core.c | 21 +++++++++++++++++---- 5 files changed, 40 insertions(+), 50 deletions(-) diff --git a/arch/arm64/include/asm/perf_event.h b/arch/arm64/include/asm/perf_event.h index 31a5584ed423..ee45b4e77347 100644 --- a/arch/arm64/include/asm/perf_event.h +++ b/arch/arm64/include/asm/perf_event.h @@ -10,10 +10,6 @@ #include #ifdef CONFIG_PERF_EVENTS -struct pt_regs; -extern unsigned long perf_arch_instruction_pointer(struct pt_regs *regs); -extern unsigned long perf_arch_misc_flags(struct pt_regs *regs); -#define perf_arch_misc_flags(regs) perf_misc_flags(regs) #define perf_arch_bpf_user_pt_regs(regs) ®s->user_regs #endif diff --git a/arch/arm64/kernel/perf_callchain.c b/arch/arm64/kernel/perf_callchain.c index 01a9d08fc009..9b7f26b128b5 100644 --- a/arch/arm64/kernel/perf_callchain.c +++ b/arch/arm64/kernel/perf_callchain.c @@ -38,31 +38,3 @@ void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, arch_stack_walk(callchain_trace, entry, current, regs); } - -unsigned long perf_arch_instruction_pointer(struct pt_regs *regs) -{ - if (perf_guest_state()) - return perf_guest_get_ip(); - - return instruction_pointer(regs); -} - -unsigned long perf_arch_misc_flags(struct pt_regs *regs) -{ - unsigned int guest_state = perf_guest_state(); - int misc = 0; - - if (guest_state) { - if (guest_state & PERF_GUEST_USER) - misc |= PERF_RECORD_MISC_GUEST_USER; - else - misc |= PERF_RECORD_MISC_GUEST_KERNEL; - } else { - if (user_mode(regs)) - misc |= PERF_RECORD_MISC_USER; - else - misc |= PERF_RECORD_MISC_KERNEL; - } - - return misc; -} diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c index d51e5d24802b..3c5f512d2bcf 100644 --- a/arch/x86/events/core.c +++ b/arch/x86/events/core.c @@ -2942,9 +2942,6 @@ static unsigned long code_segment_base(struct pt_regs *regs) unsigned long perf_arch_instruction_pointer(struct pt_regs *regs) { - if (perf_guest_state()) - return perf_guest_get_ip(); - return regs->ip + code_segment_base(regs); } @@ -2971,17 +2968,12 @@ unsigned long perf_arch_guest_misc_flags(struct pt_regs *regs) unsigned long perf_arch_misc_flags(struct pt_regs *regs) { - unsigned int guest_state = perf_guest_state(); unsigned long misc = common_misc_flags(regs); - if (guest_state) { - misc |= perf_arch_guest_misc_flags(regs); - } else { - if (user_mode(regs)) - misc |= PERF_RECORD_MISC_USER; - else - misc |= PERF_RECORD_MISC_KERNEL; - } + if (user_mode(regs)) + misc |= PERF_RECORD_MISC_USER; + else + misc |= PERF_RECORD_MISC_KERNEL; return misc; } diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index d061e327ad54..968f3edd95e4 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -1633,8 +1633,9 @@ extern void perf_tp_event(u16 event_type, u64 count, void *record, struct task_struct *task); extern void perf_bp_event(struct perf_event *event, void *data); -extern unsigned long perf_misc_flags(struct pt_regs *regs); -extern unsigned long perf_instruction_pointer(struct pt_regs *regs); +extern unsigned long perf_misc_flags(struct perf_event *event, struct pt_regs *regs); +extern unsigned long perf_instruction_pointer(struct perf_event *event, + struct pt_regs *regs); #ifndef perf_arch_misc_flags # define perf_arch_misc_flags(regs) \ @@ -1645,6 +1646,22 @@ extern unsigned long perf_instruction_pointer(struct pt_regs *regs); # define perf_arch_bpf_user_pt_regs(regs) regs #endif +#ifndef perf_arch_guest_misc_flags +static inline unsigned long perf_arch_guest_misc_flags(struct pt_regs *regs) +{ + unsigned long guest_state = perf_guest_state(); + + if (guest_state & PERF_GUEST_USER) + return PERF_RECORD_MISC_GUEST_USER; + + if (guest_state & PERF_GUEST_ACTIVE) + return PERF_RECORD_MISC_GUEST_KERNEL; + + return 0; +} +# define perf_arch_guest_misc_flags(regs) perf_arch_guest_misc_flags(regs) +#endif + static inline bool has_branch_stack(struct perf_event *event) { return event->attr.sample_type & PERF_SAMPLE_BRANCH_STACK; diff --git a/kernel/events/core.c b/kernel/events/core.c index eeabbf791a8c..c5e57c024d9a 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -6921,13 +6921,26 @@ void perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *cbs) EXPORT_SYMBOL_GPL(perf_unregister_guest_info_callbacks); #endif -unsigned long perf_misc_flags(struct pt_regs *regs) +static bool should_sample_guest(struct perf_event *event) { + return !event->attr.exclude_guest && perf_guest_state(); +} + +unsigned long perf_misc_flags(struct perf_event *event, + struct pt_regs *regs) +{ + if (should_sample_guest(event)) + return perf_arch_guest_misc_flags(regs); + return perf_arch_misc_flags(regs); } -unsigned long perf_instruction_pointer(struct pt_regs *regs) +unsigned long perf_instruction_pointer(struct perf_event *event, + struct pt_regs *regs) { + if (should_sample_guest(event)) + return perf_guest_get_ip(); + return perf_arch_instruction_pointer(regs); } @@ -7743,7 +7756,7 @@ void perf_prepare_sample(struct perf_sample_data *data, __perf_event_header__init_id(data, event, filtered_sample_type); if (filtered_sample_type & PERF_SAMPLE_IP) { - data->ip = perf_instruction_pointer(regs); + data->ip = perf_instruction_pointer(event, regs); data->sample_flags |= PERF_SAMPLE_IP; } @@ -7907,7 +7920,7 @@ void perf_prepare_header(struct perf_event_header *header, { header->type = PERF_RECORD_SAMPLE; header->size = perf_sample_data_size(data, event); - header->misc = perf_misc_flags(regs); + header->misc = perf_misc_flags(event, regs); /* * If you're adding more sample types here, you likely need to do