linux-kernel - Re: [PATCH 1/2] kvm: Remove ability to assign a device without iommu support

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Message-ID: <4EF04F54.9010500@siemens.com>
Date:	Tue, 20 Dec 2011 10:03:16 +0100
From:	Jan Kiszka <jan.kiszka@...mens.com>
To:	Sasha Levin <levinsasha928@...il.com>
CC:	Alex Williamson <alex.williamson@...hat.com>,
	"avi@...hat.com" <avi@...hat.com>,
	"kvm@...r.kernel.org" <kvm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] kvm: Remove ability to assign a device without iommu
 support

On 2011-12-20 09:49, Sasha Levin wrote:
> On Mon, 2011-12-19 at 20:19 -0700, Alex Williamson wrote:
>> This option has no users and it exposes a security hole that we
>> can allow devices to be assigned without iommu protection.  Make
>> KVM_DEV_ASSIGN_ENABLE_IOMMU a mandatory option.
>>
>> Signed-off-by: Alex Williamson <alex.williamson@...hat.com>
>> ---
>>
>>  virt/kvm/assigned-dev.c |   18 +++++++++---------
>>  1 files changed, 9 insertions(+), 9 deletions(-)
>>
>> diff --git a/virt/kvm/assigned-dev.c b/virt/kvm/assigned-dev.c
>> index 3ad0925..a251a28 100644
>> --- a/virt/kvm/assigned-dev.c
>> +++ b/virt/kvm/assigned-dev.c
>> @@ -487,6 +487,9 @@ static int kvm_vm_ioctl_assign_device(struct kvm *kvm,
>>  	struct kvm_assigned_dev_kernel *match;
>>  	struct pci_dev *dev;
>>  
>> +	if (!(assigned_dev->flags & KVM_DEV_ASSIGN_ENABLE_IOMMU))
>> +		return -EINVAL;
> 
> Could we just drop KVM_DEV_ASSIGN_ENABLE_IOMMU and do it by default?
> calling KVM_ASSIGN_PCI_DEVICE without that flag set it pretty
> meaningless.

There is that thing called "backward compatibility". :)

Jan

-- 
Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux
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