KVM: kvm-io: support cookies
Add new functions kvm_io_bus_{read,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 <cornelia.huck@de.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index a63d83e..ec590ae 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -160,8 +160,12 @@
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_read_cookie(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr,
+ int len, void *val, long cookie);
int kvm_io_bus_register_dev(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr,
int len, struct kvm_io_device *dev);
int kvm_io_bus_unregister_dev(struct kvm *kvm, enum kvm_bus bus_idx,
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 1580dd4..71960fb 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2863,11 +2863,48 @@
return off;
}
+static int __kvm_io_bus_write(struct kvm_io_bus *bus,
+ struct kvm_io_range *range, const void *val)
+{
+ int idx;
+
+ idx = kvm_io_bus_get_first_dev(bus, range->addr, range->len);
+ if (idx < 0)
+ return -EOPNOTSUPP;
+
+ while (idx < bus->dev_count &&
+ kvm_io_bus_sort_cmp(range, &bus->range[idx]) == 0) {
+ if (!kvm_iodevice_write(bus->range[idx].dev, range->addr,
+ range->len, val))
+ return idx;
+ idx++;
+ }
+
+ return -EOPNOTSUPP;
+}
+
/* kvm_io_bus_write - called under kvm->slots_lock */
int kvm_io_bus_write(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr,
int len, const void *val)
{
- int idx;
+ struct kvm_io_bus *bus;
+ struct kvm_io_range range;
+ int r;
+
+ range = (struct kvm_io_range) {
+ .addr = addr,
+ .len = len,
+ };
+
+ bus = srcu_dereference(kvm->buses[bus_idx], &kvm->srcu);
+ r = __kvm_io_bus_write(bus, &range, val);
+ return r < 0 ? r : 0;
+}
+
+/* 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)
+{
struct kvm_io_bus *bus;
struct kvm_io_range range;
@@ -2877,14 +2914,35 @@
};
bus = srcu_dereference(kvm->buses[bus_idx], &kvm->srcu);
- idx = kvm_io_bus_get_first_dev(bus, addr, len);
+
+ /* 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 cookie;
+
+ /*
+ * cookie contained garbage; fall back to search and return the
+ * correct cookie value.
+ */
+ return __kvm_io_bus_write(bus, &range, val);
+}
+
+static int __kvm_io_bus_read(struct kvm_io_bus *bus, struct kvm_io_range *range,
+ void *val)
+{
+ int idx;
+
+ idx = kvm_io_bus_get_first_dev(bus, range->addr, range->len);
if (idx < 0)
return -EOPNOTSUPP;
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))
- return 0;
+ kvm_io_bus_sort_cmp(range, &bus->range[idx]) == 0) {
+ if (!kvm_iodevice_read(bus->range[idx].dev, range->addr,
+ range->len, val))
+ return idx;
idx++;
}
@@ -2895,7 +2953,24 @@
int kvm_io_bus_read(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr,
int len, void *val)
{
- int idx;
+ struct kvm_io_bus *bus;
+ struct kvm_io_range range;
+ int r;
+
+ range = (struct kvm_io_range) {
+ .addr = addr,
+ .len = len,
+ };
+
+ bus = srcu_dereference(kvm->buses[bus_idx], &kvm->srcu);
+ r = __kvm_io_bus_read(bus, &range, val);
+ return r < 0 ? r : 0;
+}
+
+/* kvm_io_bus_read_cookie - called under kvm->slots_lock */
+int kvm_io_bus_read_cookie(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr,
+ int len, void *val, long cookie)
+{
struct kvm_io_bus *bus;
struct kvm_io_range range;
@@ -2905,18 +2980,19 @@
};
bus = srcu_dereference(kvm->buses[bus_idx], &kvm->srcu);
- idx = kvm_io_bus_get_first_dev(bus, addr, len);
- if (idx < 0)
- return -EOPNOTSUPP;
- while (idx < bus->dev_count &&
- kvm_io_bus_sort_cmp(&range, &bus->range[idx]) == 0) {
- if (!kvm_iodevice_read(bus->range[idx].dev, addr, len, val))
- return 0;
- idx++;
- }
+ /* 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_read(bus->range[cookie].dev, addr, len,
+ val))
+ return cookie;
- return -EOPNOTSUPP;
+ /*
+ * cookie contained garbage; fall back to search and return the
+ * correct cookie value.
+ */
+ return __kvm_io_bus_read(bus, &range, val);
}
/* Caller must hold slots_lock. */
