Add a new function kvm_io_bus_write_cookie() that allows users of the kvm io infrastructure to use a cookie value to speed up lookup of a device on an io bus.
Signed-off-by: Cornelia Huck <[email protected]> --- include/linux/kvm_host.h | 2 ++ virt/kvm/kvm_main.c | 44 ++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 46 insertions(+) diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index e3aae6d..2d298fc 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -159,6 +159,8 @@ enum kvm_bus { int kvm_io_bus_write(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr, int len, const void *val); +int kvm_io_bus_write_cookie(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr, + int len, const void *val, long *cookie); int kvm_io_bus_read(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr, int len, void *val); int kvm_io_bus_register_dev(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr, diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 1580dd4..222475a 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -2891,6 +2891,50 @@ int kvm_io_bus_write(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr, return -EOPNOTSUPP; } +/* kvm_io_bus_write_cookie - called under kvm->slots_lock */ +int kvm_io_bus_write_cookie(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr, + int len, const void *val, long *cookie) +{ + int idx, ret = -EOPNOTSUPP; + struct kvm_io_bus *bus; + struct kvm_io_range range; + + range = (struct kvm_io_range) { + .addr = addr, + .len = len, + }; + + bus = srcu_dereference(kvm->buses[bus_idx], &kvm->srcu); + + /* First try the device referenced by *cookie. */ + if ((*cookie >= 0) && (*cookie < bus->dev_count) && + (kvm_io_bus_sort_cmp(&range, &bus->range[*cookie]) == 0)) + if (!kvm_iodevice_write(bus->range[*cookie].dev, addr, len, + val)) + return 0; + + /* + * *cookie contained garbage; fall back to search and return the + * correct value in *cookie. + */ + idx = kvm_io_bus_get_first_dev(bus, addr, len); + if (idx < 0) + goto out; + + while (idx < bus->dev_count && + kvm_io_bus_sort_cmp(&range, &bus->range[idx]) == 0) { + if (!kvm_iodevice_write(bus->range[idx].dev, addr, len, val)) { + ret = 0; + goto out; + } + idx++; + } + idx = -ENOENT; +out: + *cookie = idx; + return ret; +} + /* kvm_io_bus_read - called under kvm->slots_lock */ int kvm_io_bus_read(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr, int len, void *val) -- 1.8.2.2 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
