From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-yb1-f202.google.com (mail-yb1-f202.google.com [209.85.219.202]) (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 C9280150994 for ; Wed, 20 Nov 2024 16:45:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.219.202 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732121133; cv=none; b=NSCu/1OFC5ip9chJtXxFskKPYaa2M4T9wke8nXoXuS2sg01DOaAmHLUOR+x0C4dUIYUHZvhcYrj28RacOTnA3s6KcJ9XMR+ndY4YX0QdbmO+ABLGzMgxqDrXIxzni47wQ8vDkHer8dekAawhRI/wdLKAGo3Grl3BgvP8nwmxIWc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732121133; c=relaxed/simple; bh=atBL+bq6+6djW/2Iaq1n5OzAjtgj/78bksKGJWYuQ1I=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=hxbemg0WKLFNAJfxQZrrNmt0X19M+yDv6nCLMQTwisJ1YCmQuzCFUioIJpxWwqCrhkfoW7EFlmeplN+3JvN0z1df5oACWT5hoE2Q//SR92R2ct7C36m6QJYszxG+oD7D0jIeIfDpvqV0jta1lEpiSCM4/dvkaBrhltASwq5jRyk= 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=gTY9dj5s; arc=none smtp.client-ip=209.85.219.202 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="gTY9dj5s" Received: by mail-yb1-f202.google.com with SMTP id 3f1490d57ef6-e38aae1bdb8so5167170276.0 for ; Wed, 20 Nov 2024 08:45:31 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1732121130; x=1732725930; 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=tygqKFbg+ArMhOWF5Yig1w6NXblyM3/JZLFP5+5GacQ=; b=gTY9dj5skMgeeJ+GFfKi94Z4ifJMyKjexzIQ9GFMT0KBUP+UkVcLTeQWg+7Wh3AunE AO6lEMQz2SKurfERzp60DNXmb9GMTSGALMlRV7YvJ++gWt7uO3sgbGACC6xETR6vyBVr vUC1Kj1Vdc6RUDBWUCv8/j8VSfgQobBJdmY/96lpkyBNDPpwO2rFNyqsbolzFS+Tt60w Idi/fk1JHqlzwY5ohQ4CHAQKO+NDmfZyqpFaRT3pGItbwr9kSCLIOLDjk/2Ovegrf/29 /J8WWZrr9RoA1edo7iB9gHa/reTRvJy0X6l7m7/N/wBHMw45rcTETOIhC8MW3CZI5u8d hHFQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1732121130; x=1732725930; 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=tygqKFbg+ArMhOWF5Yig1w6NXblyM3/JZLFP5+5GacQ=; b=nj9DpXs3NNpvyYyDg7DKjqqMWfU7z/MfIeaF2rrKDRN+tm6mZYdSKknpzsiYXGDAML OiL47V3dhp3lH2g0wwkneHeUnnr6/NESO7+B6cUs7aVYllDsGk1HzlkIxlyXipknFoTg hMuumuVutKueeQNuKfe1Hz01vCbT6GaTztDXbZG9DML2t0679lyz01xsMpGYm7zW8JQc lZ3sofqgRoRdFM5osuS46zaWOPC33UXuJgtxqSW9zJYcLi7/PObmLcVzGCv1jMgkkIim wLIz7YX8nEnxpXJRzGlAy9yNkF7o7DqSQLWOdCloM8hoMF0GG6lCG5/RK59lamk5vkvU zRCg== X-Forwarded-Encrypted: i=1; AJvYcCWTDNKSNRuy1EpCetPT1yr9REHrpRxb/iAAtwmc9dHCVUS2KDvJUXMjRViw/3k4v54kBPA=@vger.kernel.org X-Gm-Message-State: AOJu0YzOPtwU0zppWAYu9MRhDZph1pbDWsRf0sK8tcswgZb142TL7Jzt renvV4WQDH52RZHXc5gDpzmwsm3Igk5yN9gD7qbEgJJIH4QpSo3NPXaOfWhfFNk1sXzzJpWg1Gm 1bQ== X-Google-Smtp-Source: AGHT+IFYE+jm3yiya0/yDKPXKQmXpVzHcYjlo1U85vuIz90XeZaFiWv84vDiWNxcprGDNlPAvHLOb3hc2Zw= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:9d:3983:ac13:c240]) (user=seanjc job=sendgmr) by 2002:a25:698a:0:b0:e38:bf01:4df9 with SMTP id 3f1490d57ef6-e38cb718fa0mr10347276.9.1732121130735; Wed, 20 Nov 2024 08:45:30 -0800 (PST) Date: Wed, 20 Nov 2024 08:45:29 -0800 In-Reply-To: <2ec98cd1-e96e-4f17-a615-a5eac54a7004@linux.intel.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20240801045907.4010984-1-mizhang@google.com> <20240801045907.4010984-20-mizhang@google.com> <2ec98cd1-e96e-4f17-a615-a5eac54a7004@linux.intel.com> Message-ID: Subject: Re: [RFC PATCH v3 19/58] KVM: x86/pmu: Plumb through pass-through PMU to vcpu for Intel CPUs From: Sean Christopherson To: Dapeng Mi Cc: Mingwei Zhang , Paolo Bonzini , Xiong Zhang , Kan Liang , Zhenyu Wang , Manali Shukla , Sandipan Das , Jim Mattson , Stephane Eranian , Ian Rogers , Namhyung Kim , gce-passthrou-pmu-dev@google.com, Samantha Alt , Zhiyuan Lv , Yanfei Xu , Like Xu , Peter Zijlstra , Raghavendra Rao Ananta , kvm@vger.kernel.org, linux-perf-users@vger.kernel.org Content-Type: text/plain; charset="us-ascii" On Wed, Nov 20, 2024, Dapeng Mi wrote: > > On 11/19/2024 10:54 PM, Sean Christopherson wrote: > > On Thu, Aug 01, 2024, Mingwei Zhang wrote: > >> Plumb through pass-through PMU setting from kvm->arch into kvm_pmu on each > >> vcpu created. Note that enabling PMU is decided by VMM when it sets the > >> CPUID bits exposed to guest VM. So plumb through the enabling for each pmu > >> in intel_pmu_refresh(). > > Why? As with the per-VM snapshot, I see zero reason for this to exist, it's > > simply: > > > > kvm->arch.enable_pmu && enable_mediated_pmu && pmu->version; > > > > And in literally every correct usage of pmu->passthrough, kvm->arch.enable_pmu > > and pmu->version have been checked (though implicitly), i.e. KVM can check > > enable_mediated_pmu and nothing else. > > Ok, too many passthrough_pmu flags indeed confuse readers. Besides these > dependencies, mediated vPMU also depends on lapic_in_kernel(). We need to > set enable_mediated_pmu to false as well if lapic_in_kernel() returns false. No, just kill the entire vPMU. Also, the need for an in-kernel APIC isn't unique to the mediated PMU. KVM simply drops PMIs if there's no APIC. If we're feeling lucky, we could try a breaking change like so: diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c index fcd188cc389a..bb08155f6198 100644 --- a/arch/x86/kvm/pmu.c +++ b/arch/x86/kvm/pmu.c @@ -817,7 +817,7 @@ void kvm_pmu_refresh(struct kvm_vcpu *vcpu) pmu->pebs_data_cfg_mask = ~0ull; bitmap_zero(pmu->all_valid_pmc_idx, X86_PMC_IDX_MAX); - if (!vcpu->kvm->arch.enable_pmu) + if (!vcpu->kvm->arch.enable_pmu || !lapic_in_kernel(vcpu)) return; static_call(kvm_x86_pmu_refresh)(vcpu); If we don't want to risk breaking weird setups, we could restrict the behavior to the mediated PMU being enabled: diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c index fcd188cc389a..bc9673190574 100644 --- a/arch/x86/kvm/pmu.c +++ b/arch/x86/kvm/pmu.c @@ -817,7 +817,8 @@ void kvm_pmu_refresh(struct kvm_vcpu *vcpu) pmu->pebs_data_cfg_mask = ~0ull; bitmap_zero(pmu->all_valid_pmc_idx, X86_PMC_IDX_MAX); - if (!vcpu->kvm->arch.enable_pmu) + if (!vcpu->kvm->arch.enable_pmu || + (!lapic_in_kernel(vcpu) && enable_mediated_pmu)) return; static_call(kvm_x86_pmu_refresh)(vcpu);