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[34.168.104.7]) by smtp.gmail.com with ESMTPSA id m1-20020a170902db0100b00186a2274382sm8586776plx.76.2022.11.02.09.33.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 02 Nov 2022 09:33:19 -0700 (PDT) Date: Wed, 2 Nov 2022 16:33:15 +0000 From: Sean Christopherson To: Peter Xu Subject: Re: [PATCH v7 1/9] KVM: x86: Introduce KVM_REQ_DIRTY_RING_SOFT_FULL Message-ID: References: <20221031003621.164306-1-gshan@redhat.com> <20221031003621.164306-2-gshan@redhat.com> <867d0de4b0.wl-maz@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: Cc: shuah@kernel.org, kvm@vger.kernel.org, Marc Zyngier , andrew.jones@linux.dev, dmatlack@google.com, will@kernel.org, shan.gavin@gmail.com, bgardon@google.com, kvmarm@lists.linux.dev, pbonzini@redhat.com, zhenyzha@redhat.com, catalin.marinas@arm.com, kvmarm@lists.cs.columbia.edu, ajones@ventanamicro.com X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu On Wed, Nov 02, 2022, Peter Xu wrote: > Might be slightly off-topic: I didn't quickly spot how do we guarantee two > threads doing KVM_RUN ioctl on the same vcpu fd concurrently. I know > that's insane and could have corrupted things, but I just want to make sure > e.g. even a malicious guest app won't be able to trigger host warnings. kvm_vcpu_ioctl() takes the vCPU's mutex: static long kvm_vcpu_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg) { ... /* * Some architectures have vcpu ioctls that are asynchronous to vcpu * execution; mutex_lock() would break them. */ r = kvm_arch_vcpu_async_ioctl(filp, ioctl, arg); if (r != -ENOIOCTLCMD) return r; if (mutex_lock_killable(&vcpu->mutex)) return -EINTR; switch (ioctl) { case KVM_RUN: { _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pg1-f181.google.com (mail-pg1-f181.google.com [209.85.215.181]) (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 599701E9F9 for ; Wed, 2 Nov 2022 16:33:20 +0000 (UTC) Received: by mail-pg1-f181.google.com with SMTP id b5so16697646pgb.6 for ; Wed, 02 Nov 2022 09:33:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; 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=bSpvtaO5+biFCdXjgWOU/VG7HbNWLZ5uq+eRXSvuuCM=; b=QFzFFdsD02xgwNnv6w/5D3h0dWbBgJ42EmoGbAgWbOReIP7ibvMB1sHHN5oEGVDyK2 bk3kncpJvgSara7MPPqv92ajq9XrSKjcvnywOsb4pV2qvmxneWfV7ARhIkMOGJwlrz8R 1Wwd/25n0QydVBeAVmeDEjCCXnRkwe9F3P5rzk+d4bD1ddvkvul8tu19r92ToFUVyoGx nlwWSse6N6Jrp3BrkQdIfBw3LZGgL0c72+hR7wt3XtF30HeXkl7FuQ+WbQd2KaROGHaG irDvrqhCVigzw0R9bF16EmQWLdUFa8qhbnJy8fQMwqr8Dq2eNuzsKxKGR7dvUWm40Zes M5Lw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; 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=bSpvtaO5+biFCdXjgWOU/VG7HbNWLZ5uq+eRXSvuuCM=; b=hr3bwNN7m7IRxq0j0mBXswaDnSiEI9suqEdL9GiWpv+JQspUozmnrjoqvJQWp2GnHr R1/EcmLHvoMXIWR4qhwpkXQBIcyZCMgQErUStdZk5ef34fsSKaeijhjyr9wngwY10uRz +322Qf7ae5pUFxRk0NQUdNV8JfY1ajmiYpiQfwrJrtlXfcBrPldfk95IQISdhrgYF1xj oVS04wX4yUADyX7hlis1HMFN4VurfTZ1YKmvFmlVXEvoSHptfo15SYPU98iQCjyBA/T1 z/fCJYI+/ordi4CCLtxT9MKqiDt5Etm9t7tFNHqXOBf58UeF/z3vQT/zMcMwP+72i/Tm ShDA== X-Gm-Message-State: ACrzQf2ZSAbX8t/exjP+wodqR/YiMpxU0oPYMos8zPlDIInKhetImD48 qaBJd8BxBLivJDBnlAhEfA/sVXEaK3hn4A== X-Google-Smtp-Source: AMsMyM7/IFIrAzLF68OTsZpwvpWxXuJLq80r9JuhA6FJpKg68htFc94IYvOx1OmW0dUzBtPQISiKSQ== X-Received: by 2002:a63:fc12:0:b0:45f:a6e3:7559 with SMTP id j18-20020a63fc12000000b0045fa6e37559mr22400123pgi.237.1667406799666; Wed, 02 Nov 2022 09:33:19 -0700 (PDT) Received: from google.com (7.104.168.34.bc.googleusercontent.com. [34.168.104.7]) by smtp.gmail.com with ESMTPSA id m1-20020a170902db0100b00186a2274382sm8586776plx.76.2022.11.02.09.33.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 02 Nov 2022 09:33:19 -0700 (PDT) Date: Wed, 2 Nov 2022 16:33:15 +0000 From: Sean Christopherson To: Peter Xu Cc: Marc Zyngier , Gavin Shan , kvmarm@lists.linux.dev, kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu, andrew.jones@linux.dev, ajones@ventanamicro.com, bgardon@google.com, catalin.marinas@arm.com, dmatlack@google.com, will@kernel.org, pbonzini@redhat.com, oliver.upton@linux.dev, james.morse@arm.com, shuah@kernel.org, suzuki.poulose@arm.com, alexandru.elisei@arm.com, zhenyzha@redhat.com, shan.gavin@gmail.com Subject: Re: [PATCH v7 1/9] KVM: x86: Introduce KVM_REQ_DIRTY_RING_SOFT_FULL Message-ID: References: <20221031003621.164306-1-gshan@redhat.com> <20221031003621.164306-2-gshan@redhat.com> <867d0de4b0.wl-maz@kernel.org> 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: Message-ID: <20221102163315.QwPoHxqImO3d9i5xIaWhBRJ0bX_65LJguLBSvfoWtqo@z> On Wed, Nov 02, 2022, Peter Xu wrote: > Might be slightly off-topic: I didn't quickly spot how do we guarantee two > threads doing KVM_RUN ioctl on the same vcpu fd concurrently. I know > that's insane and could have corrupted things, but I just want to make sure > e.g. even a malicious guest app won't be able to trigger host warnings. kvm_vcpu_ioctl() takes the vCPU's mutex: static long kvm_vcpu_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg) { ... /* * Some architectures have vcpu ioctls that are asynchronous to vcpu * execution; mutex_lock() would break them. */ r = kvm_arch_vcpu_async_ioctl(filp, ioctl, arg); if (r != -ENOIOCTLCMD) return r; if (mutex_lock_killable(&vcpu->mutex)) return -EINTR; switch (ioctl) { case KVM_RUN: {