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=1794312436; b=E0tkWuwNjMmbAz3fm/o3iKSyOl1tzWm4Z6SiM3MgmVcNymZ2teqDN+pCt9/mhNj0AOxZ IZkosfb+YEoGjEvcj9Eb9DEv9cMXjgw/FRyeKO9kilxccrVpeSlkVVKM4vHL8QuAgil/0 V09KhPIuaNSdzunsCPGycoDfSSdaAFjA8NPeUYYnYg2OX0wVePDskDAtxAIFxuZvco28+ V/DzOYJ3xFb47FojY3Y740iapquu8M9v2NQ6qTgxZ2TskBooIhHP/eB07FJJ53NerawrP Vip/RGN+xLPeD3IpQAci50luKiXex4zV6PPaI9uR/zus+4L7bk9MrxbkMSQDdX8qfjg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794312436; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=Jx3SLt7x3xgQKoZ/g+VwJ2+pQlnVF++EioCk4UVifB8=; b=jQI/kEPVlQYU0BRLefLTgF5O+lYtHv4iFx5b78HixvCQ3WPSEPVmOSVVoJ6f+FqCHu1W 9V1W6zUorD9qillqOvV+B9ouj6vqNuKIcr8/z0edLeqfvSeHHQhsVFBoZTzy481ln5I/L UpbXVsC3B7h31cZodOmL/XI7HbTht2zEh2GaR1s7E/E/3fY6rKGnSuP+y+el7b31PAbFl USBnSauvx0LVTwzxmyN1UTCMPIQXATIwlgJj6BqOXM6Zumm7obfeesgjKsXr+LOYLF0aQ saencDktFo1fjPLgMGPWI+FiLDQ6MoI/sFjrxa6eAWle8AH83CM3YhJIrhUSLjQ7qRw== 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=mz2M4JFe; 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 ABE99606A321 for ; Tue, 10 Nov 2026 12:07:15 +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=mz2M4JFe Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9E5401F0089F; Tue, 10 Nov 2026 12:07:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794312435; bh=Jx3SLt7x3xgQKoZ/g+VwJ2+pQlnVF++EioCk4UVifB8=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=mz2M4JFeO6FCDI0mRsm79X/OJPv/54LRBvCaFecAUQPISO1ikboZ6u0jnT/naKBVN QNoszicgEO3k00JbqYidHwg/JAiZgC6enY61SqquNr9TSyyTzSQKFz4fbGVragg4Pe Cp3S4OZjFMuIyb54b+97QxB3CMSvmRfQ3BuHid09vPfCk+YPwEpcVDYs1PSs14YdOb w32pAiir0rquCTk6V93dT5DwlC+fTwcW8uuh8bXHAe4PIQcTVStHZvwFKHBoq2mXuc 2uMnvKda0ebK5rNqQ0PK2uqUV0vIbHk4TeqsPICIFZ9JsVXO7zOQLI2EfkxbrnG1CA +n6qs/47T3SYg== From: Sasha Levin To: stable@vger.kernel.org Cc: Karl Mehltretter , Fuad Tabba , Marc Zyngier , Sasha Levin Subject: [PATCH 5.15.y] KVM: arm64: vgic-v3: Undo assignment on iodev registration failure Date: Tue, 10 Nov 2026 07:07:13 -0500 Message-ID: <20261110120652.941189-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261107060136-failed-5.15-8a88a46b86ca@kernel.org> References: <20261107060136-failed-5.15-8a88a46b86ca@kernel.org> 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-Transfer-Encoding: 8bit From: Karl Mehltretter [ Upstream commit 8a88a46b86ca3dbbd24522760d29edfb3f24ac2a ] vgic_register_redist_iodev() assigns a redistributor region and base address to the vCPU before adding its iodev to the MMIO bus. However, the region's free_index is advanced only after registration succeeds. If kvm_io_bus_register_dev() fails, the vCPU retains the assignment while free_index still identifies the same slot as free. A later registration can therefore reuse a slot that remains assigned to the vCPU. Reserve the slot before registering its iodev. The caller holds slots_lock, so a registration failure cannot race with a later assignment. Undo the reservation and clear the cached assignment on failure. Fixes: dbd9733ab674 ("KVM: arm/arm64: Replace the single rdist region by a list") Cc: stable@vger.kernel.org Assisted-by: Codex:gpt-5.6-sol Signed-off-by: Karl Mehltretter Reviewed-by: Fuad Tabba Tested-by: Fuad Tabba Link: https://patch.msgid.link/20260831081005.41346-2-kmehltretter@gmail.com [maz: moved helper into the sole caller] Signed-off-by: Marc Zyngier [ sashal: adapted locking to rely on the caller-held kvm->lock instead of config_lock and guard(mutex). ] Signed-off-by: Sasha Levin --- arch/arm64/kvm/vgic/vgic-mmio-v3.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/arch/arm64/kvm/vgic/vgic-mmio-v3.c b/arch/arm64/kvm/vgic/vgic-mmio-v3.c index fd1fa2561520e..c3c0204b3eb1e 100644 --- a/arch/arm64/kvm/vgic/vgic-mmio-v3.c +++ b/arch/arm64/kvm/vgic/vgic-mmio-v3.c @@ -739,16 +739,21 @@ int vgic_register_redist_iodev(struct kvm_vcpu *vcpu) rd_dev->nr_regions = ARRAY_SIZE(vgic_v3_rd_registers); rd_dev->redist_vcpu = vcpu; + /* Protected by kvm->lock */ + rdreg->free_index++; + mutex_lock(&kvm->slots_lock); ret = kvm_io_bus_register_dev(kvm, KVM_MMIO_BUS, rd_base, 2 * SZ_64K, &rd_dev->dev); mutex_unlock(&kvm->slots_lock); - if (ret) - return ret; + if (ret) { + vgic_cpu->rdreg->free_index--; + vgic_cpu->rdreg = NULL; + vgic_cpu->rd_iodev.base_addr = VGIC_ADDR_UNDEF; + } - rdreg->free_index++; - return 0; + return ret; } void vgic_unregister_redist_iodev(struct kvm_vcpu *vcpu) -- 2.53.0