Hi, On 27/04/2017 20:06, Christoffer Dall wrote: > 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 <[email protected]> >> >> --- >> 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); >> +} >> + >> +/** >> + * entry_fn_t - Callback called on a table entry restore path >> + * @its: its handle >> + * @id: id of the entry >> + * @entry: pointer to the entry >> + * @opaque: pointer to an opaque data >> + * @next_offset: minimal ID offset to the next entry. 0 if this >> + * entry is the last one, 1 if the entry is invalid, >= 1 if an >> + * entry's next_offset field was truly decoded >> + * >> + * Return: < 0 on error, 0 otherwise >> + */ >> +typedef int (*entry_fn_t)(struct vgic_its *its, u32 id, void *entry, >> + void *opaque, u32 *next_offset); >> + >> +/** >> + * lookup_table - scan a contiguous table in guest RAM and applies a >> function >> + * to each entry >> + * >> + * @its: its handle >> + * @base: base gpa of the table >> + * @size: size of the table in bytes >> + * @esz: entry size in bytes >> + * @start_id: first entry's ID > > I'm a little confused. Why is this not 0? Because this is meant to be called on a second-level table as well (device table). In that case the start ID != 0. > >> + * @fn: function to apply on each entry >> + * >> + * Return: < 0 on error, 1 if last element identified, 0 otherwise > > How can you scan the entire table and not find the last element? This happens on 2d level tables. The last element might be in another 2d level table. > >> + */ >> +int lookup_table(struct vgic_its *its, gpa_t base, int size, int esz, >> + int start_id, entry_fn_t fn, void *opaque) > > Is this really a lookup? I think this should be called > 'scan_its_table'. ok no strong opinion here. > >> +{ >> + void *entry = kzalloc(esz, GFP_KERNEL); >> + struct kvm *kvm = its->dev->kvm; >> + unsigned long len = size; >> + u32 id = start_id; > > why are ids u32 and not just an unsigned long? will change that. > >> + gpa_t gpa = base; >> + int ret; >> + >> + while (len > 0) { >> + u32 next_offset; >> + size_t byte_offset; >> + >> + ret = kvm_read_guest(kvm, gpa, entry, esz); >> + if (ret) >> + goto out; >> + >> + ret = fn(its, id, entry, opaque, &next_offset); >> + if (ret < 0 || (!ret && !next_offset)) >> + goto out; >> + >> + byte_offset = next_offset * esz; >> + id += next_offset; >> + gpa += byte_offset; >> + len -= byte_offset; >> + } >> + kfree(entry); >> + return 0; >> + > > here you can just set 'ret = 0;' > >> +out: >> + kfree(entry); >> + return (ret < 0 ? ret : 1); > > and then here you can do 'return (ret <= 0 ? ret : 1)' > but I actually think it's nicer to just write: > > if (ret <= 0) > return ret; > return 1; OK
thanks Eric > >> +} >> + >> /** >> * vgic_its_save_device_tables - Save the device table and all ITT >> * into guest RAM >> -- >> 2.5.5 >> > > Thanks, > -Christoffer > _______________________________________________ kvmarm mailing list [email protected] https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
