On Fri, Apr 14, 2017 at 12:15:28PM +0200, Eric Auger wrote: > Add a generic lookup_table() helper whose role consists in > scanning a contiguous table located in guest RAM and applying > a callback on each entry. Entries can be handled as linked lists > since the callback may return an offset to the next entry and > also tell that an entry is the last one. > > Helper functions also are added to compute the device/event ID > offset to the next DTE/ITE. > > compute_next_devid_offset, compute_next_eventid_offset and > lookup_table will become static in subsequent patches > > Signed-off-by: Eric Auger <eric.auger@xxxxxxxxxx> > > --- > v4 -> v5: > - use kvm_read_guest > > v3 -> v4: > - remove static to avoid compilation warning > - correct size computation in looup_table() > - defines now encode the number of bits used for devid and eventid offsets > - use BIT() - 1 to encode the max offets > --- > virt/kvm/arm/vgic/vgic-its.c | 93 ++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 93 insertions(+) > > diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c > index 56c5123..c22b35d 100644 > --- a/virt/kvm/arm/vgic/vgic-its.c > +++ b/virt/kvm/arm/vgic/vgic-its.c > @@ -195,6 +195,8 @@ static struct its_ite *find_ite(struct vgic_its *its, u32 device_id, > > #define VITS_TYPER_IDBITS 16 > #define VITS_TYPER_DEVBITS 16 > +#define VITS_DTE_MAX_DEVID_OFFSET (BIT(14) - 1) > +#define VITS_ITE_MAX_EVENTID_OFFSET (BIT(16) - 1) > > /* > * Finds and returns a collection in the ITS collection table. > @@ -1674,6 +1676,97 @@ int vgic_its_attr_regs_access(struct kvm_device *dev, > return ret; > } > > +u32 compute_next_devid_offset(struct list_head *h, struct its_device *dev) > +{ > + struct list_head *e = &dev->dev_list; > + struct its_device *next; > + u32 next_offset; > + > + if (e->next == h) > + return 0; > + next = list_entry(e->next, struct its_device, dev_list); > + next_offset = next->device_id - dev->device_id; > + > + return min_t(u32, next_offset, VITS_DTE_MAX_DEVID_OFFSET); > +} > + > +u32 compute_next_eventid_offset(struct list_head *h, struct its_ite *ite) > +{ > + struct list_head *e = &ite->ite_list; > + struct its_ite *next; > + u32 next_offset; > + > + if (e->next == h) > + return 0; > + next = list_entry(e->next, struct its_ite, ite_list); > + next_offset = next->event_id - ite->event_id; > + > + return min_t(u32, next_offset, VITS_ITE_MAX_EVENTID_OFFSET); nit: in both of these functions you can avoid the extra e variable and maybe make this slightly more readable by using these two calls instead: list_is_last(&ite->ite_list, h); next = list_next_entry(ite, ite_list); Thanks, -Christoffer