On Fri, Oct 13, 2017 at 04:22:25PM +0200, Auger Eric wrote: > Hi, > > On 13/10/2017 15:16, Christoffer Dall wrote: > > On Wed, Sep 27, 2017 at 03:28:33PM +0200, Eric Auger wrote: > >> At the moment the device table save() returns -EINVAL if > >> vgic_its_check_id() fails to return the gpa of the entry > >> associated to the device/collection id. Let vgic_its_check_id() > >> return an int instead of a bool and return a more precised > >> error value: > >> - EINVAL in case the id is out of range > >> - EFAULT if the gpa is not provisionned or is not valid > >> > > > > This is just to ease debugging, yes? > > I understood user-space should be able to discriminate between bad guest > programming and values corrupted by the userspace (regs for instance). > In first case QEMU should not abort. In latter case it should abort. So what is userspace supposed to do in the first case? > > In vgic_its_check_id we are checking the L1 entry validity bit and in > case it is invalid we can't compute the GPA of the entry. I was thinking > we should return -EFAULT in that case. But maybe returning EFAULT in > case the BASER<n> address is not reachable also is wrong because that > may be caused by the userspace writing a wrong value. Sigh ... > I think if either userspace or the guest programmed something that cannot be traversed, then you just don't save/restore the ITS properly, because it's broken anyway, so I don't think we need to replicate the *same broken state* at the destination. Maybe I'm missing part of the picture here. Thanks, -Christoffer
