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Subject[RFC] KVM: arm/arm64: Introduce KVM_DEV_ARM_ITS_CTRL_RESET
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.
Documentation/virtual/kvm/devices/arm-vgic-its.txt | 3 +++
1 file changed, 3 insertions(+)

diff --git a/Documentation/virtual/kvm/devices/arm-vgic-its.txt b/Documentation/virtual/kvm/devices/arm-vgic-its.txt
index eb06beb..ebb15c5 100644
--- a/Documentation/virtual/kvm/devices/arm-vgic-its.txt
+++ b/Documentation/virtual/kvm/devices/arm-vgic-its.txt
@@ -33,6 +33,9 @@ Groups:
request the initialization of the ITS, no additional parameter in

+ reset the ITS, no additional parameter in kvm_device_attr.addr.
save the ITS table data into guest RAM, at the location provisioned
by the guest in corresponding registers/table entries.
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