[PATCH v3 1/2] KVM: kvm-io: support cookies

Cornelia Huck
2013-07-03T13:50:38Z

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.

kvm_io_bus_{read,write} now returns the index on the bus; existing callers
have been fixed up to accept return codes > 0.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
---
arch/ia64/kvm/kvm-ia64.c | 2 +-
arch/powerpc/kvm/powerpc.c | 4 +-
arch/x86/kvm/x86.c | 6 +--
include/linux/kvm_host.h | 4 ++
virt/kvm/kvm_main.c | 102 ++++++++++++++++++++++++++++++++++++++-------
5 files changed, 97 insertions(+), 21 deletions(-)

diff --git a/arch/ia64/kvm/kvm-ia64.c b/arch/ia64/kvm/kvm-ia64.c
index 5b2dc0d..465ab54 100644
--- a/arch/ia64/kvm/kvm-ia64.c
+++ b/arch/ia64/kvm/kvm-ia64.c
@@ -250,7 +250,7 @@ mmio:
else
r = kvm_io_bus_write(vcpu->kvm, KVM_MMIO_BUS, p->addr,
p->size, &p->data);
- if (r)
+ if (r < 0)
printk(KERN_ERR"kvm: No iodevice found! addr:%lx\n", p->addr);
p->state = STATE_IORESP_READY;

diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index 6316ee3..26c44d0 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -649,7 +649,7 @@ int kvmppc_handle_load(struct kvm_run *run, struct kvm_vcpu *vcpu,

srcu_read_unlock(&vcpu->kvm->srcu, idx);

- if (!ret) {
+ if (ret >= 0) {
kvmppc_complete_mmio_load(vcpu, run);
vcpu->mmio_needed = 0;
return EMULATE_DONE;
@@ -711,7 +711,7 @@ int kvmppc_handle_store(struct kvm_run *run, struct kvm_vcpu *vcpu,

srcu_read_unlock(&vcpu->kvm->srcu, idx);

- if (!ret) {
+ if (ret >= 0) {
vcpu->mmio_needed = 0;
return EMULATE_DONE;
}
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 7d71c0f..d58744b 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3860,7 +3860,7 @@ static int vcpu_mmio_write(struct kvm_vcpu *vcpu, gpa_t addr, int len,
n = min(len, 8);
if (!(vcpu->arch.apic &&
!kvm_iodevice_write(&vcpu->arch.apic->dev, addr, n, v))
- && kvm_io_bus_write(vcpu->kvm, KVM_MMIO_BUS, addr, n, v))
+ && (kvm_io_bus_write(vcpu->kvm, KVM_MMIO_BUS, addr, n, v) < 0))
break;
handled += n;
addr += n;
@@ -3880,7 +3880,7 @@ static int vcpu_mmio_read(struct kvm_vcpu *vcpu, gpa_t addr, int len, void *v)
n = min(len, 8);
if (!(vcpu->arch.apic &&
!kvm_iodevice_read(&vcpu->arch.apic->dev, addr, n, v))
- && kvm_io_bus_read(vcpu->kvm, KVM_MMIO_BUS, addr, n, v))
+ && (kvm_io_bus_read(vcpu->kvm, KVM_MMIO_BUS, addr, n, v) < 0))
break;
trace_kvm_mmio(KVM_TRACE_MMIO_READ, n, addr, *(u64 *)v);
handled += n;
@@ -4361,7 +4361,7 @@ static int kernel_pio(struct kvm_vcpu *vcpu, void *pd)
r = kvm_io_bus_write(vcpu->kvm, KVM_PIO_BUS,
vcpu->arch.pio.port, vcpu->arch.pio.size,
pd);
- return r;
+ return (r >= 0) ? 0 : r;
}

static int emulator_pio_in_out(struct kvm_vcpu *vcpu, int size,
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index e3aae6d..60e261c9 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -159,8 +159,12 @@ 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_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..eca3e00 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2863,11 +2863,30 @@ 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;

@@ -2877,14 +2896,51 @@ 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);
+ return __kvm_io_bus_write(bus, &range, val);
+}
+
+/* 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;
+ if (!kvm_iodevice_read(bus->range[idx].dev, range->addr,
+ range->len, val))
+ return idx;
idx++;
}

@@ -2895,7 +2951,6 @@ 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;

@@ -2905,18 +2960,35 @@ 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;
+ return __kvm_io_bus_read(bus, &range, val);
+}

- 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. */
--
1.8.2.2