From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 AF5E53D9DDB; Thu, 20 Aug 2026 08:56:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787216189; cv=none; b=LkfyqG8jrSVQccdqPSRJF/SnqlQu7jYPS3Wo+U/mOnf5xPZvInNVfuORQT6K567zYO1zLTz1wSHWkgyZHXh3OSwIXhIK3wn0T6OphXALwAuDc9tOyieKaPpKIV2jUEwMz6g+iORPQQBJ7XqptfvowaLMbL8ab4x80UONq3qieP4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787216189; c=relaxed/simple; bh=IHlSvMwq9tSKhGemCiip+/nEfQRm1nM1gvcM4DJggVA=; h=Date:Message-ID:From:To:Cc:Subject:In-Reply-To:References: MIME-Version:Content-Type; b=Jomks1ynjI74bFnHx0TBxveGcCIYzQ1taKY9VbqBrjEHryfPtWRzb5yxRVOkt+Zr7QgtCrTxzCYDmNLcadPCOx1kCrEPP5za6gdrY53HnK35bcsyQerqd2vLFY58sOyt1qlDj8P0ZWuTyGiGxH6RUlqcitQVsISnDCFk5eUU4sc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=QZOx0Ruq; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="QZOx0Ruq" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3FC6E1F000E9; Thu, 20 Aug 2026 08:56:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787216188; bh=5FzXYhM0M5jzCRYnzBUAIuHT1gsO3TFgi0kl9BxMwWs=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=QZOx0RuqO1AZi6vfaxCS69JVJbuy1tnf6htquabluybdKcOrfuInrjhp1abtP0NYG E2rGsaLsIt40lRQVnkk9yrO4rF2g9TsQmHu+EDSImK7n6rj6MMGpVBKM86AiIy3k9h u2/6+eHKvjQnxnMgaPP0eDQpfUWCrV86U1x+khHDxGS/RGvsu8U8piw5r8zgJW3cyR 4pCypm+N68+YRg5DSMHfpFaZGQhvMo9SWKDFaDvoTWybpblK0KeZvYtCgSvYg14bCc r5iG1PMJ22CynDXEiSng2xFl/1JAEO+Bckv2vfT6jQb8jffh6FtGlh6PqFGXnKQxHZ Uwa/d4OHhAJwg== Received: from sofa.misterjones.org ([185.219.108.64] helo=lobster-girl.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.98.2) (envelope-from ) id 1wwyZW-0000000HDi7-0kgy; Thu, 20 Aug 2026 08:56:26 +0000 Date: Thu, 20 Aug 2026 09:58:57 +0100 Message-ID: <874igpp3qm.wl-maz@kernel.org> From: Marc Zyngier To: Karl Mehltretter Cc: Oliver Upton , kvmarm@lists.linux.dev, Fuad Tabba , Joey Gouly , Steffen Eiden , Suzuki K Poulose , Zenghui Yu , Catalin Marinas , Will Deacon , Paolo Bonzini , Shuah Khan , Eric Auger , Christoffer Dall , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH v2 3/5] KVM: arm64: vgic-v3: Unregister redistributors before freeing regions In-Reply-To: <20260819224229.82948-4-kmehltretter@gmail.com> References: <20260819224229.82948-1-kmehltretter@gmail.com> <20260819224229.82948-4-kmehltretter@gmail.com> 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/30.1 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org 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: kmehltretter@gmail.com, oupton@kernel.org, kvmarm@lists.linux.dev, tabba@google.com, joey.gouly@arm.com, seiden@linux.ibm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, catalin.marinas@arm.com, will@kernel.org, pbonzini@redhat.com, shuah@kernel.org, eric.auger@redhat.com, christoffer.dall@arm.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-kselftest@vger.kernel.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false On Wed, 19 Aug 2026 23:42:27 +0100, Karl Mehltretter wrote: > > vgic_unregister_redist_iodev() uses rdreg to return its region slot. During > VM teardown, kvm_vgic_destroy() frees the regions before unregistering > their iodevs, so vgic_v3_free_redist_region() must first clear every rdreg > pointer. > > Unregister the iodevs before kvm_vgic_dist_destroy(), while the regions are > still alive. Temporarily drop config_lock because > vgic_unregister_redist_iodev() takes it; slots_lock remains held for the > MMIO bus updates. The region destructor no longer needs the vCPU scan. > > Suggested-by: Marc Zyngier > Assisted-by: Codex:gpt-5.6-sol > Signed-off-by: Karl Mehltretter > --- > arch/arm64/kvm/vgic/vgic-init.c | 11 +++++++---- > arch/arm64/kvm/vgic/vgic-mmio-v3.c | 9 --------- > 2 files changed, 7 insertions(+), 13 deletions(-) > > diff --git a/arch/arm64/kvm/vgic/vgic-init.c b/arch/arm64/kvm/vgic/vgic-init.c > index 0a3df6d3a691..df6d0bdda4a9 100644 > --- a/arch/arm64/kvm/vgic/vgic-init.c > +++ b/arch/arm64/kvm/vgic/vgic-init.c > @@ -570,14 +570,17 @@ void kvm_vgic_destroy(struct kvm *kvm) > kvm_for_each_vcpu(i, vcpu, kvm) > __kvm_vgic_vcpu_destroy(vcpu); > > + if (kvm->arch.vgic.vgic_model == KVM_DEV_TYPE_ARM_VGIC_V3) { > + mutex_unlock(&kvm->arch.config_lock); > + kvm_for_each_vcpu(i, vcpu, kvm) > + vgic_unregister_redist_iodev(vcpu); > + mutex_lock(&kvm->arch.config_lock); > + } This really is awful. It'd be easy enough to have an "already locked" primitive (__vgic_unassign_redist_iodev()) that doesn't take the config_lock, and simply write this as: kvm_for_each_vcpu(i, vcpu, kvm) { struct vgic_io_device *rd_dev = &vcpu->arch.vgic_cpu.rd_iodev; kvm_io_bus_unregister_dev(vcpu->kvm, KVM_MMIO_BUS, &rd_dev->dev); __vgic_unassign_redist_iodev(vcpu); } or another variation on the same theme. The other bit of interest is in __kvm_vgic_vcpu_destroy(), and its conditional removal of the RD iodevs. Can't we just get rid of this whole block altogether now that we have a saner failing path? Thanks, M. -- Jazz isn't dead. It just smells funny.