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 0B146168B4 for ; Mon, 8 May 2023 09:53:30 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 51346C4339C; Mon, 8 May 2023 09:53:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1683539610; bh=lE0iVr6vFooUwwIpPU3OVgO1WvMteKCsrak9kTdvJ50=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Qn7HddVzsMfGKvtPe6Je/0TLhg2ZkyO4tPoe3piROS9VksNKo+CjIW4OLcArFnYhi rO2kh6Tk8lHSmtvgLKn8bBj/1+ylVFAasVdHU3+mgCJpwkakOwTfehL4qCnsdGGf6q DAYwY4Zo2BThRQPOta+TLZJ0vHNhPbqoAVgHi6gg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Oliver Upton , Marc Zyngier Subject: [PATCH 6.1 080/611] KVM: arm64: vgic: Dont acquire its_lock before config_lock Date: Mon, 8 May 2023 11:38:42 +0200 Message-Id: <20230508094424.676793467@linuxfoundation.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230508094421.513073170@linuxfoundation.org> References: <20230508094421.513073170@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Oliver Upton commit 49e5d16b6fc003407a33a9961b4bcbb970bd1c76 upstream. commit f00327731131 ("KVM: arm64: Use config_lock to protect vgic state") was meant to rectify a longstanding lock ordering issue in KVM where the kvm->lock is taken while holding vcpu->mutex. As it so happens, the aforementioned commit introduced yet another locking issue by acquiring the its_lock before acquiring the config lock. This is obviously wrong, especially considering that the lock ordering is well documented in vgic.c. Reshuffle the locks once more to take the config_lock before the its_lock. While at it, sprinkle in the lockdep hinting that has become popular as of late to keep lockdep apprised of our ordering. Cc: stable@vger.kernel.org Fixes: f00327731131 ("KVM: arm64: Use config_lock to protect vgic state") Signed-off-by: Oliver Upton Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20230412062733.988229-1-oliver.upton@linux.dev Signed-off-by: Greg Kroah-Hartman --- arch/arm64/kvm/vgic/vgic-its.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) --- a/arch/arm64/kvm/vgic/vgic-its.c +++ b/arch/arm64/kvm/vgic/vgic-its.c @@ -1958,6 +1958,16 @@ static int vgic_its_create(struct kvm_de mutex_init(&its->its_lock); mutex_init(&its->cmd_lock); + /* Yep, even more trickery for lock ordering... */ +#ifdef CONFIG_LOCKDEP + mutex_lock(&dev->kvm->arch.config_lock); + mutex_lock(&its->cmd_lock); + mutex_lock(&its->its_lock); + mutex_unlock(&its->its_lock); + mutex_unlock(&its->cmd_lock); + mutex_unlock(&dev->kvm->arch.config_lock); +#endif + its->vgic_its_base = VGIC_ADDR_UNDEF; INIT_LIST_HEAD(&its->device_list); @@ -2752,15 +2762,14 @@ static int vgic_its_ctrl(struct kvm *kvm return 0; mutex_lock(&kvm->lock); - mutex_lock(&its->its_lock); if (!lock_all_vcpus(kvm)) { - mutex_unlock(&its->its_lock); mutex_unlock(&kvm->lock); return -EBUSY; } mutex_lock(&kvm->arch.config_lock); + mutex_lock(&its->its_lock); switch (attr) { case KVM_DEV_ARM_ITS_CTRL_RESET: @@ -2774,9 +2783,9 @@ static int vgic_its_ctrl(struct kvm *kvm break; } + mutex_unlock(&its->its_lock); mutex_unlock(&kvm->arch.config_lock); unlock_all_vcpus(kvm); - mutex_unlock(&its->its_lock); mutex_unlock(&kvm->lock); return ret; }