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SubjectRe: [RFC] KVM: arm/arm64: Introduce KVM_DEV_ARM_ITS_CTRL_RESET
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.


Jazz is not dead. It just smells funny.

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