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

Gleb Natapov
2013-07-03T13:56:42Z

On Wed, Jul 03, 2013 at 03:50:38PM +0200, Cornelia Huck wrote:
> 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)
No need to change kvm_io_bus_(read|write) return value now. Just do
there:

r = __kvm_io_bus_write(bus, &range, val);
return r >=0 ? 0 : r;

> 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

--
Gleb.