From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj1-f74.google.com (mail-pj1-f74.google.com [209.85.216.74]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4413E1AAA1F for ; Wed, 8 Jan 2025 19:31:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.74 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736364669; cv=none; b=PAt1hk+Pt1lHu0yOhjXfw6G2fKPuSZY6ZfmW1/W7CcQNIvb9GPMYylD/SvKYTgInRqTYAWzPtGCv/9gUoXow+UDSmM7nArNft+cMk4Jj7f8ud6p5GUTWKht1eZ8s2Ls0oSc8qvMw9oHTlAgLfTcpRru5oInbvwBtEyBIzUnTTkA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736364669; c=relaxed/simple; bh=j8Lp5ED8JKW0YShHaZyKoSTKpSj2NUc/6Fr7W0m9S8w=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=bBRM5yd80WphI6gelBu5LG/BYjpcObQyHAFXPg1S5JWPnBEU5MPiyu3SiDkDBfr7Cp2YrJpwtttjqQw4Fd5WZPW6Em06VdusMa+q211d9ZoqlGAe7BG9wag378eEUHRo7niIw9AILyFrUxMulI8oN4jHAQs4EJvF/nl9Bhj89fs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=bP4zn/lp; arc=none smtp.client-ip=209.85.216.74 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="bP4zn/lp" Received: by mail-pj1-f74.google.com with SMTP id 98e67ed59e1d1-2ef35de8901so232885a91.3 for ; Wed, 08 Jan 2025 11:31:08 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1736364667; x=1736969467; darn=vger.kernel.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=8QSU9WBtVajX3qFErB85rNsWVoVpkqgMri6VMcSJZxE=; b=bP4zn/lpDXwJPr4oIJkIMLaeJcL7shODw1/XJ56WquJ3x0t/ZwG/E+pFM+Hczwt28L TKNcNqPhSgVoFocA1FyG884oo/PBo1oQdxlCtc7lV6z17Jugohu5+Wn+E+5EDdFdRAUe bku9KoSCEZ47bKrw5CDYCnRXupmp7Invr3jIgrkMeupRATf82n7kmeAuiPjBGAedIYqK fSuZGfSzo1g/oJJweojVgrKueD4GI6JiYp+dc1/0hLzVhEqru1ugsURz/WOr3SXsCIZh 99pJ4WrJ18tWEnX865wVE9FQRQahrfd7MRdyD++MTeyFmWv0GHVVUqsaf0f19YpmPqXm YF9Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1736364667; x=1736969467; 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=8QSU9WBtVajX3qFErB85rNsWVoVpkqgMri6VMcSJZxE=; b=F1l4p/d1xOhpReScbGehwhAeWZ7suM59rTWRMbspAAC3ABpVfJCDkm8+Se5OSePsr/ 0Nvh5TV4COyZKLfiXLgHmqnmj22THQPONMfIJq2etn85mWJYAiV2Rv7FYLGhnf43eyYH B961c1GDDCDki9S4G5i6Au1rdnSe79W2cNiBKqnbi5DJg4zRBxZuxLFqbQzbyY+PWfI/ dZvezvmFQJfOg5FjOjgqfzqyWQh7l2ReSiD4E8Ldu9u1e7KwpT5czb3tH06d3nP1+wdQ 37YGuOC2Ia4p+KHkCVvaghyx2SSjChwDKLjG1FgTgxNf3+hyV6bkawphxL2BrrNyTeof b9tA== X-Forwarded-Encrypted: i=1; AJvYcCWLnctfEcJrZLa86XhQNSDAzKiRx51isS8L4wGBdT8ANQCysM7ryzK6RsupfrYI/j1fA1LiyjdKrlgttQ8=@vger.kernel.org X-Gm-Message-State: AOJu0Yyep7fDn6oKqV0LB3lKV4SZzBdgpemff4VmukIj4Ov48rXn/yDB oVBblmU9CpmSTZKNaaJX5UKXkCFwNyC4Hj3yxcotitFseLHmHsxVvm8VI8WMSLSijV8qqXJBaRu CEg== X-Google-Smtp-Source: AGHT+IEqs6N7PPsng94De5dx3mkquV1TM1SYIb1HlxfQlEumNRj6VcGiC4B0xcwZFGnydYIZent9HBZlEJA= X-Received: from pfwo12.prod.google.com ([2002:a05:6a00:1bcc:b0:72b:ccb:c99b]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a20:c89b:b0:1e1:dd97:7881 with SMTP id adf61e73a8af0-1e88d12745bmr6952244637.23.1736364667587; Wed, 08 Jan 2025 11:31:07 -0800 (PST) Date: Wed, 8 Jan 2025 11:31:06 -0800 In-Reply-To: <20240918205319.3517569-6-coltonlewis@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20240918205319.3517569-1-coltonlewis@google.com> <20240918205319.3517569-6-coltonlewis@google.com> Message-ID: Subject: Re: [PATCH v2 5/6] KVM: x86: selftests: Test core events From: Sean Christopherson To: Colton Lewis Cc: kvm@vger.kernel.org, Mingwei Zhang , Jinrong Liang , Jim Mattson , Aaron Lewis , Paolo Bonzini , Shuah Khan , linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="us-ascii" On Wed, Sep 18, 2024, Colton Lewis wrote: > Test events on core counters by iterating through every combination of > events in amd_pmu_zen_events with every core counter. > > For each combination, calculate the appropriate register addresses for > the event selection/control register and the counter register. The > base addresses and layout schemes change depending on whether we have > the CoreExt feature. > > To do the testing, reuse GUEST_TEST_EVENT to run a standard known > workload. Decouple it from guest_assert_event_count (now > guest_assert_intel_event_count) to generalize to AMD. > > Then assert the most specific detail that can be reasonably known > about the counter result. Exact count is defined and known for some > events and for other events merely asserted to be nonzero. > > Note on exact counts: AMD counts one more branch than Intel for the > same workload. Though I can't confirm a reason, the only thing it > could be is the boundary of the loop instruction being counted > differently. Presumably, when the counter reaches 0 and execution > continues to the next instruction, AMD counts this as a branch and > Intel doesn't IIRC, VMRUN is counted as a branch instruction for the guest. Assuming my memory is correct, that means this test is going to be flaky as an asynchronous exit, e.g. due to a host IRQ, during the measurement loop will inflate the count. I'm not entirely sure what to do about that :-( > +static void __guest_test_core_event(uint8_t event_idx, uint8_t counter_idx) > +{ > + /* One fortunate area of actual compatibility! This register /* * This is the proper format for multi-line comments. We are not the * crazy net/ folks. */ > + * layout is the same for both AMD and Intel. It's not, actually. There are differences in the layout, it just so happens that the differences don't throw a wrench in things. The comments in tools/testing/selftests/kvm/include/x86_64/pmu.h document this fairly well, I don't see any reason to have a comment here. > + */ > + uint64_t eventsel = ARCH_PERFMON_EVENTSEL_OS | > + ARCH_PERFMON_EVENTSEL_ENABLE | > + amd_pmu_zen_events[event_idx]; Align the indentation. uint64_t eventsel = ARCH_PERFMON_EVENTSEL_OS | ARCH_PERFMON_EVENTSEL_ENABLE | amd_pmu_zen_events[event_idx]; > + bool core_ext = this_cpu_has(X86_FEATURE_PERF_CTR_EXT_CORE); > + uint64_t esel_msr_base = core_ext ? MSR_F15H_PERF_CTL : MSR_K7_EVNTSEL0; > + uint64_t cnt_msr_base = core_ext ? MSR_F15H_PERF_CTR : MSR_K7_PERFCTR0; > + uint64_t msr_step = core_ext ? 2 : 1; > + uint64_t esel_msr = esel_msr_base + msr_step * counter_idx; > + uint64_t cnt_msr = cnt_msr_base + msr_step * counter_idx; This pattern of code is copy+pasted in three functions. Please add macros and/or helpers to consolidate things. These should also be uint32_t, not 64. It's a bit evil, but one approach would be to add a macro to iterate over all PMU counters. Eating the VM-Exit for the CPUID to get X86_FEATURE_PERF_CTR_EXT_CORE each time is unfortunate, but I doubt/hope it's not problematic in practice. If the cost is meaningful, we could figure out a way to cache the info, e.g. something awful like this might work: /* Note, this relies on guest state being recreated between each test. */ static int has_perfctr_core = -1; if (has_perfctr_core == -1) has_perfctr_core = this_cpu_has(X86_FEATURE_PERFCTR_CORE); if (has_perfctr_core) { static bool get_pmu_counter_msrs(int idx, uint32_t *eventsel, uint32_t *pmc) { if (this_cpu_has(X86_FEATURE_PERFCTR_CORE)) { *eventsel = MSR_F15H_PERF_CTL + idx * 2; *pmc = MSR_F15H_PERF_CTR + idx * 2; } else { *eventsel = MSR_K7_EVNTSEL0 + idx; *pmc = MSR_K7_PERFCTR0 + idx; } return true; } #define for_each_pmu_counter(_i, _nr_counters, _eventsel, _pmc) \ for (_i = 0; i < _nr_counters; _i++) \ if (get_pmu_counter_msrs(_i, &_eventsel, _pmc)) \ static void guest_test_core_events(void) { uint8_t nr_counters = guest_nr_core_counters(); uint32_t eventsel_msr, pmc_msr; int i, j; for (i = 0; i < NR_AMD_ZEN_EVENTS; i++) { for_each_pmu_counter(j, nr_counters, eventsel_msr, pmc_msr) { uint64_t eventsel = ARCH_PERFMON_EVENTSEL_OS | ARCH_PERFMON_EVENTSEL_ENABLE | amd_pmu_zen_events[event_idx]; GUEST_TEST_EVENT(pmc_msr, eventsel_msr, eventsel, ""); guest_assert_amd_event_count(i, j, pmc_msr); if (!is_forced_emulation_enabled) continue; GUEST_TEST_EVENT(pmc_msr, eventsel_msr, eventsel, KVM_FEP); guest_assert_amd_event_count(i, j, pmc_msr); } } }