On Thu, Sep 14, 2017 at 10:57:28AM +0200, 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 > the KVM_DEV_ARM_VGIC_GRP_CTRL group. > > Upon this action, we can invalidate the various memory structures > pointed by GITS_BASERn and GITS_CBASER, free the ITS internal caches It's more about freeing the cached data structures than what the BASERn registers point to, really, but ok. > and reset the relevant registers. > > Signed-off-by: Eric Auger <eric.auger@xxxxxxxxxx> > > --- > > 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 crazy about that idea. > --- > 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 > kvm_device_attr.addr. > > + KVM_DEV_ARM_ITS_CTRL_RESET > + reset the ITS, no additional parameter in kvm_device_attr.addr. > + I can't find information in the spec about what 'reset the ITS' means. So I think we need to describe this a little more carefully. Which assumptions does a user have after calling this. > KVM_DEV_ARM_ITS_SAVE_TABLES > save the ITS table data into guest RAM, at the location provisioned > by the guest in corresponding registers/table entries. > -- > 2.5.5 > Thanks, -Christoffer
