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[34.125.73.210]) by smtp.gmail.com with ESMTPSA id lr31-20020a056a00739f00b006ecfe1c9630sm3368108pfb.92.2024.04.12.13.44.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 12 Apr 2024 13:44:45 -0700 (PDT) Date: Fri, 12 Apr 2024 13:44:41 -0700 From: David Matlack To: James Houghton Cc: Andrew Morton , Paolo Bonzini , Yu Zhao , Marc Zyngier , Oliver Upton , Sean Christopherson , Jonathan Corbet , James Morse , Suzuki K Poulose , Zenghui Yu , Catalin Marinas , Will Deacon , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , Shaoqin Huang , Gavin Shan , Ricardo Koller , Raghavendra Rao Ananta , Ryan Roberts , David Rientjes , Axel Rasmussen , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, kvm@vger.kernel.org, linux-mm@kvack.org, linux-trace-kernel@vger.kernel.org Subject: Re: [PATCH v3 5/7] KVM: x86: Participate in bitmap-based PTE aging Message-ID: References: <20240401232946.1837665-1-jthoughton@google.com> <20240401232946.1837665-6-jthoughton@google.com> Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240401232946.1837665-6-jthoughton@google.com> On 2024-04-01 11:29 PM, James Houghton wrote: > Only handle the TDP MMU case for now. In other cases, if a bitmap was > not provided, fallback to the slowpath that takes mmu_lock, or, if a > bitmap was provided, inform the caller that the bitmap is unreliable. I think this patch will trigger a lockdep assert in kvm_tdp_mmu_age_gfn_range kvm_tdp_mmu_handle_gfn for_each_tdp_mmu_root __for_each_tdp_mmu_root kvm_lockdep_assert_mmu_lock_held ... because it walks tdp_mmu_roots without holding mmu_lock. Yu's patch[1] added a lockless walk to the TDP MMU. We'd need something similar here and also update the comment above tdp_mmu_roots describing how tdp_mmu_roots can be read locklessly. [1] https://lore.kernel.org/kvmarm/ZItX64Bbx5vdjo9M@google.com/ From mboxrd@z Thu Jan 1 00:00:00 1970 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 1313AC4345F for ; Fri, 12 Apr 2024 20:45:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=Lj1qnOSWvRPsrhIFuuU61SR8lYooEPk8BBr+UGrBmIk=; b=ikWCJ+47sqL8is /aJQ3gcLNTm2wQnNiLqrWir1QPqtC1mxFwO2L5VGaDN6UpPL48YJd/TCd1KIR/tS8yX6V0iooxqMJ 7veCXU4x01jcsO8IzhNkpQGnhn7XMfo5tqJmB0SA6OpDkba+tMOWx0dXpDcQuUGinOaTAvkrHrVyw ZYZ7fQIq5OJf9OsiOWz7Y3t9XudUNxMB8hfw5RPHE1n1L3Jqrnl9xkgCPxE01eqqf10wyS99snjKj lJaw+8MwkOmD8uoUIbHKGd4Gzbsg7Wp2ap0lK/shVAIR78sh8y+Pevm9aizJE6oll32nF7wxxqGSu W5tjOo5oeUR4TfjHKMTg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1rvNlS-00000001FOU-3oSk; Fri, 12 Apr 2024 20:44:50 +0000 Received: from mail-pf1-x430.google.com ([2607:f8b0:4864:20::430]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1rvNlP-00000001FNN-3Gog for linux-arm-kernel@lists.infradead.org; Fri, 12 Apr 2024 20:44:49 +0000 Received: by mail-pf1-x430.google.com with SMTP id d2e1a72fcca58-6ece8991654so1255569b3a.3 for ; Fri, 12 Apr 2024 13:44:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1712954686; x=1713559486; darn=lists.infradead.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=7z+VKNpPRufGEfzC58h5hLq5eFFz0DWRzzztXBo7m7o=; b=FETzOgP9oclbi/4hBozZEkKPpk9Nzb0j+v2AMzigz1mhfT3qcfnHobyac3XWrioolR y5HB1DV3N0MHPvvODuPNTh0Ewqu6hM+Kn7JVdmI/jJtylQFsUF8gNnEui7xyzCE0NkiG iUIWPg1zJRwv3VK5tcjg0SQa7IJmhzS0QZt9mYDTO2qHWWW5aIoghGg9IFZfRmuYdHGp SXcoHOZ2nQNAKp802X8z0jJuhEq9zci3b8e8dRNCj8nWmnNoeb/UfvQR2FNcEvrqbjhT Gi2iLAAf0uGVE7F3AeFKZybW6VSBldA6k9/CBSiElBuiHSnZIBfy62i6ttkZwD/zyfp7 +dDw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1712954686; x=1713559486; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=7z+VKNpPRufGEfzC58h5hLq5eFFz0DWRzzztXBo7m7o=; b=ovoAS23HzsIPCgVzXwumEyuJEKwnC3TWopUq7o42D6i5sP9zHDlDqdg8KmSpT7zM/R KaskvGu45N83uoJRTWO6CnzfpH0FpAp3azUodbAZi6sWirozJ54bpduG+FuGVbjM+QCQ V0FZfjiBjlA5RkRg1ecJxBTzjeFrKS9+wUjHbqbK93tIAgZ0NaGvJhxBETXwikAWPoT3 Xll7Ud5uaxzm9H0HlkLhmP0Z1sq3YPLQ+BgbJ3tfhtieNn3iexKH75J3kcoA9e1KGUBc TjuqxI+qzxp7h+uh+8kqpow7L2XpLy+vJCwcKGZN430EWDd8ay1cTaGnBjl7YXmbORMI w6EA== X-Forwarded-Encrypted: i=1; AJvYcCXa4kpzBoUvAv94z38u7zcRhsN6QlUuhtVUGXTkvvnZMzMLglh970VV29wVs6fg2iMOY+iz80GzjwLtSK5F/pEeH8eOnGsvOnvF2YUjwQjUE74g5cc= X-Gm-Message-State: AOJu0YymB1qSDx/ATCpq45PslyuE8Sbl3HscKJ9NjTx6BuEVhNihRh2x 3YaCarr65NG+BRk8X8+uNJs5D6YxUDr6+UcIsdCETKY3Wd4Foyw7ORWEHeSfSg== X-Google-Smtp-Source: AGHT+IFZFKdCRdPaL3Vb0XTMjnUQNtJVoruOo48GxoyfTAhTrJOnmmO+jVgRuAaY5z2jRsVdxr03aw== X-Received: by 2002:a05:6a20:8428:b0:1a9:6c42:77f5 with SMTP id c40-20020a056a20842800b001a96c4277f5mr4669546pzd.59.1712954685790; Fri, 12 Apr 2024 13:44:45 -0700 (PDT) Received: from google.com (210.73.125.34.bc.googleusercontent.com. [34.125.73.210]) by smtp.gmail.com with ESMTPSA id lr31-20020a056a00739f00b006ecfe1c9630sm3368108pfb.92.2024.04.12.13.44.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 12 Apr 2024 13:44:45 -0700 (PDT) Date: Fri, 12 Apr 2024 13:44:41 -0700 From: David Matlack To: James Houghton Cc: Andrew Morton , Paolo Bonzini , Yu Zhao , Marc Zyngier , Oliver Upton , Sean Christopherson , Jonathan Corbet , James Morse , Suzuki K Poulose , Zenghui Yu , Catalin Marinas , Will Deacon , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , Shaoqin Huang , Gavin Shan , Ricardo Koller , Raghavendra Rao Ananta , Ryan Roberts , David Rientjes , Axel Rasmussen , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, kvm@vger.kernel.org, linux-mm@kvack.org, linux-trace-kernel@vger.kernel.org Subject: Re: [PATCH v3 5/7] KVM: x86: Participate in bitmap-based PTE aging Message-ID: References: <20240401232946.1837665-1-jthoughton@google.com> <20240401232946.1837665-6-jthoughton@google.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20240401232946.1837665-6-jthoughton@google.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240412_134447_840092_5A231B74 X-CRM114-Status: GOOD ( 11.75 ) 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: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 2024-04-01 11:29 PM, James Houghton wrote: > Only handle the TDP MMU case for now. In other cases, if a bitmap was > not provided, fallback to the slowpath that takes mmu_lock, or, if a > bitmap was provided, inform the caller that the bitmap is unreliable. I think this patch will trigger a lockdep assert in kvm_tdp_mmu_age_gfn_range kvm_tdp_mmu_handle_gfn for_each_tdp_mmu_root __for_each_tdp_mmu_root kvm_lockdep_assert_mmu_lock_held ... because it walks tdp_mmu_roots without holding mmu_lock. Yu's patch[1] added a lockless walk to the TDP MMU. We'd need something similar here and also update the comment above tdp_mmu_roots describing how tdp_mmu_roots can be read locklessly. [1] https://lore.kernel.org/kvmarm/ZItX64Bbx5vdjo9M@google.com/ _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel