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 mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by smtp.lore.kernel.org (Postfix) with ESMTP id 697F0C4332F for ; Wed, 2 Nov 2022 16:49:16 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id D2E844B88E; Wed, 2 Nov 2022 12:49:15 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Authentication-Results: mm01.cs.columbia.edu (amavisd-new); dkim=softfail (fail, message has been altered) header.i=@kernel.org Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 20oQUX2axYaM; Wed, 2 Nov 2022 12:49:12 -0400 (EDT) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id F12654B8B0; Wed, 2 Nov 2022 12:49:11 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 2D6D54B88E for ; Wed, 2 Nov 2022 12:49:11 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id GUNpXVGGdEO4 for ; Wed, 2 Nov 2022 12:49:06 -0400 (EDT) Received: from sin.source.kernel.org (sin.source.kernel.org [145.40.73.55]) by mm01.cs.columbia.edu (Postfix) with ESMTPS id 520354B880 for ; Wed, 2 Nov 2022 12:49:06 -0400 (EDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by sin.source.kernel.org (Postfix) with ESMTPS id C60D1CE2275; Wed, 2 Nov 2022 16:49:00 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id F31E4C4347C; Wed, 2 Nov 2022 16:48:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1667407739; bh=tRsjyo8FJNFmccLVQxVnp+9o24jB8i/WgRkJHPFRPwc=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=MvpDxsR2jiiQIBMQXKVibQlhUlCcJbHm10uOjW/GhMkD32pAdGVp6UWM8uIoPaz34 Csa3F2U/HEJBXYzCIivYREnLVIAmcZVybuj4Y+nsYGF32/vwpnOrrWOy/KGrB0EjGZ Wav4AajmwtgrU+qIbTEK7lmP7oGLoFkgNk6mCvM+uBW6QO6EIPT6K8eYskPab9voGG VA8RItZcs89WGWDhUDrHiqYmw2zg1YIOHSv+83eKK0Ki7a33RYF/SMzPWiNFwTguPi qEr6m/4IYsn1YbjSU/V/7Di4ZjVXmULEHlRT6do79Ynocz/+MqwczVo4IeHQvEOk+y zgJ2xgOuY20sA== Received: from sofa.misterjones.org ([185.219.108.64] helo=wait-a-minute.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1oqGvA-003GhM-QP; Wed, 02 Nov 2022 16:48:56 +0000 Date: Wed, 02 Nov 2022 16:48:26 +0000 Message-ID: <87zgd9fgkl.wl-maz@kernel.org> From: Marc Zyngier To: Peter Xu Subject: Re: [PATCH v7 1/9] KVM: x86: Introduce KVM_REQ_DIRTY_RING_SOFT_FULL In-Reply-To: References: <20221031003621.164306-1-gshan@redhat.com> <20221031003621.164306-2-gshan@redhat.com> <867d0de4b0.wl-maz@kernel.org> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/27.1 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: peterx@redhat.com, seanjc@google.com, gshan@redhat.com, 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 X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Cc: shuah@kernel.org, kvm@vger.kernel.org, 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, 02 Nov 2022 16:23:16 +0000, 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. In kvm_vcpu_ioctl(): if (mutex_lock_killable(&vcpu->mutex)) <----- this return -EINTR; switch (ioctl) { case KVM_RUN: { struct pid *oldpid; r = -EINVAL; if (arg) We simply don't allow two concurrent ioctls to the same vcpu, let alone two KVM_RUN. M. -- Without deviation from the norm, progress is not possible. _______________________________________________ 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 smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6670A1E9FF for ; Wed, 2 Nov 2022 16:48:59 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id F31E4C4347C; Wed, 2 Nov 2022 16:48:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1667407739; bh=tRsjyo8FJNFmccLVQxVnp+9o24jB8i/WgRkJHPFRPwc=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=MvpDxsR2jiiQIBMQXKVibQlhUlCcJbHm10uOjW/GhMkD32pAdGVp6UWM8uIoPaz34 Csa3F2U/HEJBXYzCIivYREnLVIAmcZVybuj4Y+nsYGF32/vwpnOrrWOy/KGrB0EjGZ Wav4AajmwtgrU+qIbTEK7lmP7oGLoFkgNk6mCvM+uBW6QO6EIPT6K8eYskPab9voGG VA8RItZcs89WGWDhUDrHiqYmw2zg1YIOHSv+83eKK0Ki7a33RYF/SMzPWiNFwTguPi qEr6m/4IYsn1YbjSU/V/7Di4ZjVXmULEHlRT6do79Ynocz/+MqwczVo4IeHQvEOk+y zgJ2xgOuY20sA== Received: from sofa.misterjones.org ([185.219.108.64] helo=wait-a-minute.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1oqGvA-003GhM-QP; Wed, 02 Nov 2022 16:48:56 +0000 Date: Wed, 02 Nov 2022 16:48:26 +0000 Message-ID: <87zgd9fgkl.wl-maz@kernel.org> From: Marc Zyngier To: Peter Xu Cc: Sean Christopherson , 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 In-Reply-To: References: <20221031003621.164306-1-gshan@redhat.com> <20221031003621.164306-2-gshan@redhat.com> <867d0de4b0.wl-maz@kernel.org> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/27.1 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO) Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: peterx@redhat.com, seanjc@google.com, gshan@redhat.com, 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 X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Message-ID: <20221102164826.hxQBU7m1jgq8kTruwPx68r4XalUYyq5ZHfjdp0PN2Ds@z> On Wed, 02 Nov 2022 16:23:16 +0000, 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. In kvm_vcpu_ioctl(): if (mutex_lock_killable(&vcpu->mutex)) <----- this return -EINTR; switch (ioctl) { case KVM_RUN: { struct pid *oldpid; r = -EINVAL; if (arg) We simply don't allow two concurrent ioctls to the same vcpu, let alone two KVM_RUN. M. -- Without deviation from the norm, progress is not possible.