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[79.180.2.31]) by smtp.gmail.com with ESMTPSA id l12sm2068012edn.83.2021.02.05.07.03.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 05 Feb 2021 07:03:42 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1612537429; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=0YVwlnyhma8tw3aikrEQmkUKeFTYcxGuyLeIpvMJSOU=; b=EqNeaZ+b4qXcXkWmkZjqNT2vAdoGgpXHEnWgmosv5FpwjII95zI/b31M2taVuY5nD5Xrma CFDQI1rZywluuKEaPOiqLe+8pCYfS3gm3NPeWqkDkitH0y06WlFx2+qmzqIChF9VdCJosx LrRgiHK9fD5aFfGicqea/E6mjjx8Htk= X-MC-Unique: jEhGuVdHMtGuKn6avrIWHA-1 X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=0YVwlnyhma8tw3aikrEQmkUKeFTYcxGuyLeIpvMJSOU=; b=ZOk5hsgASvvVNbGsILZgFvRFwKEfUsUZ6J6zPvI+jU9+j2g6YwfizytuxoJc8rBwj7 CNVP1d6nS7cWfslxgahaFcfgwhI7+p3fU3P03QcxaeohhsFhKYu32+qeFCknfmMXTbMf z8kKiWMB9GlY+QC5wOYgzWbLY7diQ3LW3S78JTI/hhyD6tXqEhqZ7EKZGCftXHSb/6Yj AZLzVeqP1TAmHs8YOqbwHsAllzmolJjjh1WfPy94zAx0zhrYHEy/NFG3MlKihJQagE03 1jjwhXPbI7t33K3fJUhmVRWjnw0a5MIh2pjDIzByx66j9m6TIvZfq7BHlQFJdGYIVCPJ xBXQ== X-Gm-Message-State: AOAM532JF5c6kQh9ine3ZZ2sGWwJch+Eusk3NZ50NzoK7DpIDHlYKF57 czD+DduDfMrS1thB+8re24/tPCvMlM/M6S2ac9iXYe7YUuzRKFWPaoSRfrKGffhJW8yeEvydCoY 46PDdcFQBjYzFKPhh1hr7PxTkVEKley+wmdHC451oSRF9JvDUEYdHe2Mw+mqN X-Received: by 2002:a50:bf4a:: with SMTP id g10mr3759973edk.201.1612537423776; Fri, 05 Feb 2021 07:03:43 -0800 (PST) X-Google-Smtp-Source: ABdhPJzBBrxNGYfwiVbSab/8GAANM2FFTaEMhekLRBWouXRJNuNvq5AjR2EVFCMWymsGI+Ho1W4LzA== X-Received: by 2002:a50:bf4a:: with SMTP id g10mr3759944edk.201.1612537423494; Fri, 05 Feb 2021 07:03:43 -0800 (PST) Date: Fri, 5 Feb 2021 10:03:41 -0500 From: "Michael S. Tsirkin" To: qemu-devel@nongnu.org Subject: [PULL v2 04/16] virtio-mmio: fix guest kernel crash with SHM regions Message-ID: <20210205150135.94643-5-mst@redhat.com> References: <20210205150135.94643-1-mst@redhat.com> MIME-Version: 1.0 In-Reply-To: <20210205150135.94643-1-mst@redhat.com> X-Mailer: git-send-email 2.27.0.106.g8ac3dc51b1 X-Mutt-Fcc: =sent Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=mst@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Disposition: inline Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=63.128.21.124; envelope-from=mst@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.352, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Peter Maydell , Stefano Garzarella , Laurent Vivier , Gerd Hoffmann Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Laurent Vivier In the kernel, virtio_gpu_init() uses virtio_get_shm_region() since commit 6076a9711dc5 ("drm/virtio: implement blob resources: probe for host = visible region") but vm_get_shm_region() unconditionally uses VIRTIO_MMIO_SHM_SEL to get the address and the length of the region. commit 38e895487afc ("virtio: Implement get_shm_region for MMIO transport" As this is not implemented in QEMU, address and length are 0 and passed as is to devm_request_mem_region() that triggers a crash: [drm:virtio_gpu_init] *ERROR* Could not reserve host visible region Unable to handle kernel NULL pointer dereference at virtual address (ptrv= al) According to the comments in the kernel, a non existent shared region has a length of (u64)-1. This is what we return now with this patch to disable the region. Signed-off-by: Laurent Vivier Message-Id: <20201220163539.2255963-1-laurent@vivier.eu> Acked-by: Gerd Hoffmann Reviewed-by: Stefano Garzarella Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin --- hw/virtio/virtio-mmio.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/hw/virtio/virtio-mmio.c b/hw/virtio/virtio-mmio.c index e1b5c3b81e..610661d6a5 100644 --- a/hw/virtio/virtio-mmio.c +++ b/hw/virtio/virtio-mmio.c @@ -191,6 +191,14 @@ static uint64_t virtio_mmio_read(void *opaque, hwaddr = offset, unsigned size) return 0; } return vdev->generation; + case VIRTIO_MMIO_SHM_LEN_LOW: + case VIRTIO_MMIO_SHM_LEN_HIGH: + /* + * VIRTIO_MMIO_SHM_SEL is unimplemented + * according to the linux driver, if region length is -1 + * the shared memory doesn't exist + */ + return -1; case VIRTIO_MMIO_DEVICE_FEATURES_SEL: case VIRTIO_MMIO_DRIVER_FEATURES: case VIRTIO_MMIO_DRIVER_FEATURES_SEL: --=20 MST