Hi, On 14/09/2017 19:06, Marc Zyngier wrote: > On Thu, Sep 14 2017 at 10:57:28 am BST, Eric Auger <eric.auger@xxxxxxxxxx> 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 >> 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 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. Thanks Eric > > Thoughts? > > M. >
