From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f202.google.com (mail-pl1-f202.google.com [209.85.214.202]) (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 F3189308F19 for ; Fri, 15 Aug 2025 15:51:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.202 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755273100; cv=none; b=tZfqME77pDszfebyK2E0cdUEW/IMxAA798SlifvMaf6xmVM07V36ZB3WJ3Va0KqePKupl61D5YXQeSnARRUSJmvOwGiskZSadPxhwuHIiM84oHdinDEoWu0Nspr3MjUIgBDAhfuXiiZ/wj8F35hs6+pJHrtsPf8wc1cW05yCYIk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755273100; c=relaxed/simple; bh=TC3F7GjzY+OYu16pCnRLEw1W9DDDYcqj1aSZMIOYjuI=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=PxBzLyEI9qEGRLvFGs1/BZXvxsMd+UMCZUnZd7fwNfdt/WiaxnHGdcOWJRp3rirCvRryHh5qrLUVBQBCQtvsTwzw5oXKbRMNJPIS88tN8Uui9MaeOnPpWUZDaGa4AMQHNFb/oBfA3hi1kZEtRpoM6jO7TisvwTGNbcGUxgCKIG4= 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=VbUwWtvm; arc=none smtp.client-ip=209.85.214.202 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="VbUwWtvm" Received: by mail-pl1-f202.google.com with SMTP id d9443c01a7336-244570600a1so24406775ad.1 for ; Fri, 15 Aug 2025 08:51:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1755273098; x=1755877898; 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=yLuuQdqXBRGyu60+ieS//bbxP+3AVwFN22YqAdloirM=; b=VbUwWtvmPg2mzJ1mDCrvoA9XcEX+R1vUa2Ytu1ZtQTkrmWQBNqlULza7r07TfXRunw rgTiJih/HIKEqr7vaGDRRkBS0UnEY54fKQBbf4WBjGJVIk38G8ugO1jrZ3Xd0gSIz6cT R8STM5KEF6lEudZxvKFLWEkK0CiqcYRWCl8OZlFVyonlBmDE43x4v3HHCoaFVQYkZue0 3DDjzZSrVEJdosIX6rTshEjnnm7d/hKlnkWEy3LUwn8NqJ7LWYZ2DxJChCMoZwznWSqX TRyAEETcPbALtpKTWxzCy1T3weTv0fjnZI76Z8PrWUcFGL84VdFEXdrEadNIdzowWYYh l9NQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1755273098; x=1755877898; 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=yLuuQdqXBRGyu60+ieS//bbxP+3AVwFN22YqAdloirM=; b=Kf4jeknXWkwc6E7MWWhI8uaC6prEmXR6qHW/gtl0VYSPh5skAcvBiqDjuTt0Ge41mH 7kgJ/z4tSQsHrhpmYX2Cci258tA+Y7/gox+87WRsJcLxAGRtAK0CQFRqyNoWHKAnPXpj bIue+D3aGFI8N4YrwHfpQqrTfoevaui8FZcnE2T8PHX8XGiGEmnbEh9bZaEECE9TVFak 6kCOESMU/9r26BCLhOAQfxOwxZRW95weuxxuxDQEm4J0W+TCUMMYVcT6UgWU7tidoGOg 6GFNPOqdXrbk9JiyQhQswaMua/12Tn2l+3AeqapWqIdHy+dKRKDPKZXXbb2Oew430OOJ PyNw== X-Forwarded-Encrypted: i=1; AJvYcCU2BLuDNGI76tQz+rJpJDnSQ5JQPBYsmgbSU3wrIbNcf/xbCpZoRF4GCn1N+sTRVUad7m4db9+P3zGcs9ln3Vgn@vger.kernel.org X-Gm-Message-State: AOJu0YxJqegKzFHlU6V2tbz9GJz72Rhe5tcYws3oC3tJKGSbeYR3XG8s vCVX9Wr8/eubuzkBi1ij/lBmtQSsaTZqUH+E/KoA/w1JJSGaqMh+HS8z7Yqog9cRssYJbxKHWKA 9lQ9Qtg== X-Google-Smtp-Source: AGHT+IEixUUF/+ontXG1UvvxuaP113HP3iSlTpnTS0Og0gwZnRo8djp+nSrKI0cvN3mMbDgB4JtBQNij17k= X-Received: from pjee7.prod.google.com ([2002:a17:90b:5787:b0:321:c2d6:d1c3]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:902:cec3:b0:244:5aa5:a8b with SMTP id d9443c01a7336-2445aa50e20mr99042625ad.27.1755273098085; Fri, 15 Aug 2025 08:51:38 -0700 (PDT) Date: Fri, 15 Aug 2025 08:51:36 -0700 In-Reply-To: <20250815130436.GA3289052@noisy.programming.kicks-ass.net> Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250806195706.1650976-1-seanjc@google.com> <20250806195706.1650976-10-seanjc@google.com> <20250815130436.GA3289052@noisy.programming.kicks-ass.net> Message-ID: Subject: Re: [PATCH v5 09/44] perf/x86: Switch LVTPC to/from mediated PMI vector on guest load/put context From: Sean Christopherson To: Peter Zijlstra Cc: Marc Zyngier , Oliver Upton , Tianrui Zhao , Bibo Mao , Huacai Chen , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Xin Li , "H. Peter Anvin" , Andy Lutomirski , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Paolo Bonzini , linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, kvm@vger.kernel.org, loongarch@lists.linux.dev, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, Kan Liang , Yongwei Ma , Mingwei Zhang , Xiong Zhang , Sandipan Das , Dapeng Mi Content-Type: text/plain; charset="us-ascii" On Fri, Aug 15, 2025, Peter Zijlstra wrote: > On Wed, Aug 06, 2025 at 12:56:31PM -0700, Sean Christopherson wrote: > > > @@ -2727,6 +2739,21 @@ static struct pmu pmu = { > > .filter = x86_pmu_filter, > > }; > > > > +void arch_perf_load_guest_context(unsigned long data) > > +{ > > + u32 masked = data & APIC_LVT_MASKED; > > + > > + apic_write(APIC_LVTPC, > > + APIC_DM_FIXED | PERF_GUEST_MEDIATED_PMI_VECTOR | masked); > > + this_cpu_write(x86_guest_ctx_loaded, true); > > +} > > I'm further confused, why would this ever be masked? The idea is to match the guest's LVTPC state so that KVM doesn't trigger IRQ VM-Exits on counter overflow when the guest's LVTPC is masked.