From mboxrd@z Thu Jan  1 00:00:00 1970
From: Avi Kivity <avi@redhat.com>
Subject: Re: [PATCH 1/4] s390/kvm: Handle hosts not supporting
	s390-virtio.
Date: Thu, 09 Aug 2012 13:03:57 +0300
Message-ID: <50238B0D.2060604@redhat.com>
References: <1344351168-2568-1-git-send-email-cornelia.huck@de.ibm.com>
	<1344351168-2568-2-git-send-email-cornelia.huck@de.ibm.com>
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Cc: linux-s390 <linux-s390@vger.kernel.org>,
	Anthony Liguori <aliguori@us.ibm.com>,
	Rusty Russell <rusty@rustcorp.com.au>, KVM <kvm@vger.kernel.org>,
	Carsten Otte <cotte@de.ibm.com>, Sebastian Ott <sebott@linux.vnet.ibm.com>,
	Marcelo Tosatti <mtosatti@redhat.com>,
	Heiko Carstens <heiko.carstens@de.ibm.com>,
	qemu-devel <qemu-devel@nongnu.org>, Alexander Graf <agraf@suse.de>,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	Martin Schwidefsky <schwidefsky@de.ibm.com>
To: Cornelia Huck <cornelia.huck@de.ibm.com>
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On 08/07/2012 05:52 PM, Cornelia Huck wrote:
> Running under a kvm host does not necessarily imply the presence of
> a page mapped above the main memory with the virtio information;
> however, the code includes a hard coded access to that page.
> 
> Instead, check for the presence of the page and exit gracefully
> before we hit an addressing exception if it does not exist.
> 
>  /*
>   * Init function for virtio
>   * devices are in a single page above top of "normal" mem
> @@ -443,6 +458,12 @@ static int __init kvm_devices_init(void)
>  	}
>  
>  	kvm_devices = (void *) real_memory_size;
> +	if (test_devices_support() < 0) {
> +		vmem_remove_mapping(real_memory_size, PAGE_SIZE);
> +		root_device_unregister(kvm_root);
> +		/* No error. */
> +		return 0;
> +	}
>  

Cleaner to defer root_device_register() until after the mapping has been
verified.


-- 
error compiling committee.c: too many arguments to function