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authorCornelia Huck <cornelia.huck@de.ibm.com>2013-07-03 16:30:53 +0200
committerPaolo Bonzini <pbonzini@redhat.com>2013-07-18 12:29:23 +0200
commit126a5af520eff9b99a0bb1ca4bb4a0b7973f7d5a (patch)
tree74084d4e3bb3526c132f58b0ca8b9c98065452b9 /virt
parent1c118b8226922d225a7df4127926ed2a2d73baaf (diff)
downloadlinux-stericsson-126a5af520eff9b99a0bb1ca4bb4a0b7973f7d5a.tar.gz
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>
Diffstat (limited to 'virt')
-rw-r--r--virt/kvm/kvm_main.c108
1 files changed, 92 insertions, 16 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 1580dd4ace4e..71960fb03c2a 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2863,13 +2863,33 @@ static int kvm_io_bus_get_first_dev(struct kvm_io_bus *bus,
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,
@@ -2877,14 +2897,52 @@ int kvm_io_bus_write(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr,
};
bus = srcu_dereference(kvm->buses[bus_idx], &kvm->srcu);
- idx = kvm_io_bus_get_first_dev(bus, addr, len);
+ 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;
+
+ 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 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++;
}
@@ -2895,9 +2953,9 @@ int kvm_io_bus_write(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr,
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,
@@ -2905,18 +2963,36 @@ int kvm_io_bus_read(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr,
};
bus = srcu_dereference(kvm->buses[bus_idx], &kvm->srcu);
- idx = kvm_io_bus_get_first_dev(bus, addr, len);
- if (idx < 0)
- return -EOPNOTSUPP;
+ r = __kvm_io_bus_read(bus, &range, val);
+ return r < 0 ? r : 0;
+}
- 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++;
- }
+/* 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;
- return -EOPNOTSUPP;
+ 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_read(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_read(bus, &range, val);
}
/* Caller must hold slots_lock. */