From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794050303; b=fSivAqEFNGNeH9kkGM4dOyFhozwpbqHkxVRA8CwxSkGmm58kEB8Z1igKiteN+8F+v4tL vmcWlzSkMbN8yxh8thWCS8M3UoIy96hREqsFIuwjuOjVB2CyeBEWsgVtUD0aWH4gkN/IW MyvoY+FF1jX0xTPFioK5uo7YL/wqh7+iEuptFPpUKMcFJU+pAifCh2JPfMmPXu+n2H4cd IfWb2/RrNGMikIDoXzGDEtGre9o1rB1H6/UjU8ZojRkBZszWb22WXLTZ6LBVNjXzDVzG9 TTJ+go59lZsdYEEg1nInSU4QAr26ryFVBKWAOqbuXcCmyfPoy4vVjs+LzzfourFEGTA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794050303; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=9RroseIl4/mexFraNPKjklQk18r3cyqYjcb0EejRIsg=; b=4zt4wt97WmA/FxDnAd6GRDFHNkjGqfhcC0E9hhmdYhdCQgUfP22d2wizjiwcrHRLz708 Q284/Yqx29aAVGK9821lQkn2dnMT7NY9/cGbTNJTklH27pdtYA4rmIum2dFVcTk/MzPzc KP/8Atl9o/PwcEDPwv4UNIdJ3jIp+D3Kle6jbwPllYzTI3xaZhTvy7rzpXmCm7ZgQ1cA2 Il5x8SeF/IEF7WLgqmQ19hNxNx4yxIhuOhFnCEBodxN3i6CwrrXBMywlWXiyU/npGB6Po kHiB7/7+wP/2q38nfqcBbHkkctGCYOAGDFN2/SQtklVdHABUsbrJskrYklCwJvHX3Eg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b="bLPX4/v/"; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E9128606A326 for ; Sat, 7 Nov 2026 11:18:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=bLPX4/v/ Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5D7721F0089F; Sat, 7 Nov 2026 11:18:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794050302; bh=9RroseIl4/mexFraNPKjklQk18r3cyqYjcb0EejRIsg=; h=From:To:Cc:Subject:Date; b=bLPX4/v/tniDwbpg9T8eZyZwC0B24VKVaGjukssVCh2dSv2JEcVjSU+IbMzI0Ivrh x6BG7/WU2rK5RVpymIJvyop8Qs2LQAr5GqKkltCU2JoaYUHPBb6FqmuVKArncrLVRg iIAqjAsfgKri/jNmYx4kqQ7rlO/2RWnnn8l/o2vMsVlOLqhzwkiJ0iqxPqg4nhVqaA mym2fSuWGTFWSggbeZ8BtkS0m+zzSMObfqosKvketoLmgFOrbHoZIKzGTx1nHR/dqY FEYxzyCyvcgBCsZYX1J4WDTCHnpdK9eLR1kQCHdBvVrkITtEv/EQ4wJBhVwHaLYrSH BLfOgsm9D36hg== From: Sasha Levin To: kmehltretter@gmail.com, maz@kernel.org Cc: stable@vger.kernel.org Subject: FAILED: patch "[PATCH] KVM: arm64: vgic-v3: Roll back assignments from the new region" failed to apply to 5.10-stable tree Date: Sat, 7 Nov 2026 06:18:20 -0500 Message-ID: <20261107061820-failed-5.10-a32c01324eb4@kernel.org> X-Mailer: git-send-email 2.53.0 X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The patch below does not apply to the 5.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y git checkout FETCH_HEAD git cherry-pick -x a32c01324eb494dda811912eb847b0e907cd7270 # git commit -s git send-email --to '' --in-reply-to '20261107061820-failed-5.10-a32c01324eb4@kernel.org' --subject-prefix 'PATCH 5.10.y' 'HEAD^..' Thanks, Sasha ------------------ original commit in Linus's tree ------------------ >From a32c01324eb494dda811912eb847b0e907cd7270 Mon Sep 17 00:00:00 2001 From: Karl Mehltretter Date: Mon, 31 Aug 2026 10:10:02 +0200 Subject: [PATCH] KVM: arm64: vgic-v3: Roll back assignments from the new region A failed REDIST_REGION write unregisters the redistributor iodevs of every vCPU processed before the failure. This includes vCPUs assigned to older regions. Their assignments remain cached, so a retry does not register the iodevs again. The vCPU whose registration fails has no assignment to roll back. For vCPUs processed earlier, limit rollback to those assigned to the new region. The region is removed on failure, so its free_index does not need restoring. Resetting assignments from older regions is unsafe because a vCPU can own one before kvm_for_each_vcpu() can see it. Rollback could then move free_index behind that live assignment. kvm_vgic_addr() holds slots_lock across the REDIST_REGION write. vCPU creation takes the same lock before assigning a redistributor. A concurrent vCPU cannot acquire an assignment from the new region before rollback completes. The lock also keeps rdreg valid across the config_lock drop required by MMIO-bus registration. Fixes: c011f4ea106b ("KVM: arm/arm64: Check vcpu redist base before registering an iodev") Cc: stable@vger.kernel.org Assisted-by: Codex:gpt-5.6-sol Signed-off-by: Karl Mehltretter Link: https://patch.msgid.link/20260831081005.41346-3-kmehltretter@gmail.com [maz: moved helper into the sole caller] Signed-off-by: Marc Zyngier --- arch/arm64/kvm/vgic/vgic-mmio-v3.c | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-) diff --git a/arch/arm64/kvm/vgic/vgic-mmio-v3.c b/arch/arm64/kvm/vgic/vgic-mmio-v3.c index 8fb0a3eb3457d..5ab789accc9d4 100644 --- a/arch/arm64/kvm/vgic/vgic-mmio-v3.c +++ b/arch/arm64/kvm/vgic/vgic-mmio-v3.c @@ -846,7 +846,8 @@ void vgic_unregister_redist_iodev(struct kvm_vcpu *vcpu) kvm_io_bus_unregister_dev(vcpu->kvm, KVM_MMIO_BUS, &rd_dev->dev); } -static int vgic_register_all_redist_iodevs(struct kvm *kvm) +static int vgic_register_all_redist_iodevs(struct kvm *kvm, + struct vgic_redist_region *rdreg) { struct kvm_vcpu *vcpu; unsigned long c; @@ -866,7 +867,14 @@ static int vgic_register_all_redist_iodevs(struct kvm *kvm) for (i = 0; i < c; i++) { vcpu = kvm_get_vcpu(kvm, i); + if (vcpu->arch.vgic_cpu.rdreg != rdreg) + continue; + vgic_unregister_redist_iodev(vcpu); + + guard(mutex)(&vcpu->kvm->arch.config_lock); + vcpu->arch.vgic_cpu.rdreg = NULL; + vcpu->arch.vgic_cpu.rd_iodev.base_addr = VGIC_ADDR_UNDEF; } } @@ -975,10 +983,13 @@ void vgic_v3_free_redist_region(struct kvm *kvm, struct vgic_redist_region *rdre int vgic_v3_set_redist_base(struct kvm *kvm, u32 index, u64 addr, u32 count) { + struct vgic_redist_region *rdreg; int ret; mutex_lock(&kvm->arch.config_lock); ret = vgic_v3_alloc_redist_region(kvm, index, addr, count); + if (!ret) + rdreg = vgic_v3_rdist_region_from_index(kvm, index); mutex_unlock(&kvm->arch.config_lock); if (ret) return ret; @@ -987,12 +998,9 @@ int vgic_v3_set_redist_base(struct kvm *kvm, u32 index, u64 addr, u32 count) * Register iodevs for each existing VCPU. Adding more VCPUs * afterwards will register the iodevs when needed. */ - ret = vgic_register_all_redist_iodevs(kvm); + ret = vgic_register_all_redist_iodevs(kvm, rdreg); if (ret) { - struct vgic_redist_region *rdreg; - mutex_lock(&kvm->arch.config_lock); - rdreg = vgic_v3_rdist_region_from_index(kvm, index); vgic_v3_free_redist_region(kvm, rdreg); mutex_unlock(&kvm->arch.config_lock); return ret; -- 2.53.0