From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id E525AD2FB for ; Thu, 23 Mar 2023 22:48:39 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 632CD4B3; Thu, 23 Mar 2023 15:49:23 -0700 (PDT) Received: from [192.168.122.164] (U203867.austin.arm.com [10.118.30.28]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 27FE63F766; Thu, 23 Mar 2023 15:48:32 -0700 (PDT) Message-ID: Date: Thu, 23 Mar 2023 17:48:29 -0500 Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.8.0 Subject: Re: [PATCH v2 0/4] KVM: arm64: Fix vcpu->mutex v. kvm->lock inversion Content-Language: en-US To: Oliver Upton , Marc Zyngier Cc: James Morse , Suzuki K Poulose , kvmarm@lists.linux.dev, Zenghui Yu , linux-arm-kernel@lists.infradead.org, Sean Christopherson References: <20230316211412.2651555-1-oliver.upton@linux.dev> From: Jeremy Linton In-Reply-To: <20230316211412.2651555-1-oliver.upton@linux.dev> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Hi, On 3/16/23 16:14, Oliver Upton wrote: > As it so happens, lock ordering in KVM/arm64 is completely backwards. > There's a significant amount of VM-wide state that needs to be accessed > from the context of a vCPU. Until now, this was accomplished by > acquiring the kvm->lock, but that cannot be nested within vcpu->mutex. > > This series fixes the issue with some fine-grained locking for MP state > and a new, dedicated mutex that can nest with both kvm->lock and > vcpu->mutex. > > Tested with kvmtool and QEMU scaled up to 64 vCPUs on a kernel w/ > lockdep enabled. Applies to kvmarm/next. This set makes the reported lockdep error go away for me, it also appears to complete some basic kernel/kvm testing without error as well. So, Tested-by: Jeremy Linton Thanks, > > v1: http://lore.kernel.org/kvmarm/20230308083947.3760066-1-oliver.upton@linux.dev > > v1 -> v2: > - Add a dedicated lock for serializing writes to MP state > - Inform lockdep of acquisition order at time of VM/vCPU creation > - Plug a race with GIC creation (Sean) > - Use the config_lock in GIC ITS flows as well. There is now a single > (valid) use of kvm->lock when enabling MTE. > > Oliver Upton (4): > KVM: arm64: Avoid vcpu->mutex v. kvm->lock inversion in CPU_ON > KVM: arm64: Avoid lock inversion when setting the VM register width > KVM: arm64: Use config_lock to protect data ordered against KVM_RUN > KVM: arm64: Use config_lock to protect vgic state > > arch/arm64/include/asm/kvm_host.h | 4 ++ > arch/arm64/kvm/arm.c | 45 +++++++++++++++++++---- > arch/arm64/kvm/guest.c | 2 + > arch/arm64/kvm/hypercalls.c | 4 +- > arch/arm64/kvm/pmu-emul.c | 23 +++--------- > arch/arm64/kvm/psci.c | 19 +++++----- > arch/arm64/kvm/reset.c | 16 ++++---- > arch/arm64/kvm/vgic/vgic-debug.c | 8 ++-- > arch/arm64/kvm/vgic/vgic-init.c | 33 ++++++++++------- > arch/arm64/kvm/vgic/vgic-its.c | 29 ++++++--------- > arch/arm64/kvm/vgic/vgic-kvm-device.c | 53 ++++++++++++--------------- > arch/arm64/kvm/vgic/vgic-mmio-v3.c | 4 +- > arch/arm64/kvm/vgic/vgic-mmio.c | 12 +++--- > arch/arm64/kvm/vgic/vgic-v4.c | 11 +++--- > arch/arm64/kvm/vgic/vgic.c | 2 +- > 15 files changed, 146 insertions(+), 119 deletions(-) >