[lkml]   [2017]   [Sep]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [RFC] KVM: arm/arm64: Introduce KVM_DEV_ARM_ITS_CTRL_RESET

On 14/09/2017 19:06, Marc Zyngier wrote:
> On Thu, Sep 14 2017 at 10:57:28 am BST, Eric Auger <> wrote:
>> At the moment, the in-kernel emulated ITS is not properly reset.
>> On guest restart/reset some registers keep their old values and
>> internal structures like device, ITE, collection lists are not emptied.
>> This may lead to various bugs. Among them, we can have incorrect state
>> backup or failure when saving the ITS state at early guest boot stage.
>> This patch introduces a new attribute, KVM_DEV_ARM_ITS_CTRL_RESET in
>> Upon this action, we can invalidate the various memory structures
>> pointed by GITS_BASERn and GITS_CBASER, free the ITS internal caches
>> and reset the relevant registers.
>> Signed-off-by: Eric Auger <>
>> ---
>> An alternative would consist in having the userspace writing
>> individual registers with default values: GITS_BASERn, GITS_CBASER
>> and GITS_CTLR. On kernel side we would reset related lists when
>> detecting the valid bit is set to false.
> I'm not sure this is necessarily a "either/or" situation. It looks to me
> that we're not completely doing the right thing when writing to the
> GITS_BASER registers, and that writing a new value (with the valid bit
> set or not) should have an action of some sort on the fate of the
> existing mappings.

I agree. I think whenever the GITS_BASERn or GITS_CBASER validity bit is
reset, we should empty the internal lists and assure the code does not
attempt to read the data structures in caches/RAM anymore.

I will follow up with some patches.


> Thoughts?
> M.

 \ /
  Last update: 2017-09-15 14:27    [W:0.071 / U:8.120 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site