| Message ID | 20130305091308.1a1173d1@gondolin (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, Mar 05, 2013 at 09:13:08AM +0100, Cornelia Huck wrote: > On Mon, 4 Mar 2013 21:07:41 -0300 > Marcelo Tosatti <mtosatti@redhat.com> wrote: > > > On Thu, Feb 28, 2013 at 12:33:21PM +0100, Cornelia Huck wrote: > > > Enable ioeventfd support on s390 and hook up diagnose 500 virtio-ccw > > > notifications. > > > > > > Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com> > > > --- > > > arch/s390/kvm/Kconfig | 1 + > > > arch/s390/kvm/Makefile | 2 +- > > > arch/s390/kvm/diag.c | 26 ++++++++++++++++++++++++++ > > > arch/s390/kvm/kvm-s390.c | 1 + > > > 4 files changed, 29 insertions(+), 1 deletion(-) > > > > > > diff --git a/arch/s390/kvm/Kconfig b/arch/s390/kvm/Kconfig > > > index b58dd86..3c43e30 100644 > > > --- a/arch/s390/kvm/Kconfig > > > +++ b/arch/s390/kvm/Kconfig > > > @@ -22,6 +22,7 @@ config KVM > > > select PREEMPT_NOTIFIERS > > > select ANON_INODES > > > select HAVE_KVM_CPU_RELAX_INTERCEPT > > > + select HAVE_KVM_EVENTFD > > > ---help--- > > > Support hosting paravirtualized guest machines using the SIE > > > virtualization capability on the mainframe. This should work > > > diff --git a/arch/s390/kvm/Makefile b/arch/s390/kvm/Makefile > > > index 3975722..8fe9d65 100644 > > > --- a/arch/s390/kvm/Makefile > > > +++ b/arch/s390/kvm/Makefile > > > @@ -6,7 +6,7 @@ > > > # it under the terms of the GNU General Public License (version 2 only) > > > # as published by the Free Software Foundation. > > > > > > -common-objs = $(addprefix ../../../virt/kvm/, kvm_main.o) > > > +common-objs = $(addprefix ../../../virt/kvm/, kvm_main.o eventfd.o) > > > > > > ccflags-y := -Ivirt/kvm -Iarch/s390/kvm > > > > > > diff --git a/arch/s390/kvm/diag.c b/arch/s390/kvm/diag.c > > > index a390687..1c01a99 100644 > > > --- a/arch/s390/kvm/diag.c > > > +++ b/arch/s390/kvm/diag.c > > > @@ -13,6 +13,7 @@ > > > > > > #include <linux/kvm.h> > > > #include <linux/kvm_host.h> > > > +#include <asm/virtio-ccw.h> > > > #include "kvm-s390.h" > > > #include "trace.h" > > > #include "trace-s390.h" > > > @@ -104,6 +105,29 @@ static int __diag_ipl_functions(struct kvm_vcpu *vcpu) > > > return -EREMOTE; > > > } > > > > > > +static int __diag_virtio_hypercall(struct kvm_vcpu *vcpu) > > > +{ > > > + int ret, idx; > > > + > > > + /* No virtio-ccw notification? Get out quickly. */ > > > + if (!vcpu->kvm->arch.css_support || > > > + (vcpu->run->s.regs.gprs[1] != KVM_S390_VIRTIO_CCW_NOTIFY)) > > > + return -EOPNOTSUPP; > > > + > > > + idx = srcu_read_lock(&vcpu->kvm->srcu); > > > + /* > > > + * The layout is as follows: > > > + * - gpr 2 contains the subchannel id (passed as addr) > > > + * - gpr 3 contains the virtqueue index (passed as datamatch) > > > + */ > > > + ret = kvm_io_bus_write(vcpu->kvm, KVM_VIRTIO_CCW_NOTIFY_BUS, > > > + vcpu->run->s.regs.gprs[2], > > > + 8, &vcpu->run->s.regs.gprs[3]); > > > + srcu_read_unlock(&vcpu->kvm->srcu, idx); > > > + /* kvm_io_bus_write returns -EOPNOTSUPP if it found no match. */ > > > + return ret < 0 ? ret : 0; > > > +} > > > + > > > > What about the cookie? > > This is the not-performance-optimized version which went through our > testing and which I'd like to see applied. I also have a not-yet-tested > patch that adds cookie support (see below), but I'd like to postpone > this to 3.10. I agree it's best to delay this optimization, focus on basic functionality now. As guest with cookie support is compatible with host without said support (all we do really is reserve a gpr), there won't be issues adding it later. Some comments on the draft below. > commit 8fce4a8a3478252f7ee2eb74d2732673f5911120 > Author: Cornelia Huck <cornelia.huck@de.ibm.com> > Date: Tue Feb 26 17:05:01 2013 +0100 > > virtio-ccw: ioeventfd: use cookies > > Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com> > > diff --git a/arch/s390/kvm/diag.c b/arch/s390/kvm/diag.c > index 1c01a99..bd2a013 100644 > --- a/arch/s390/kvm/diag.c > +++ b/arch/s390/kvm/diag.c > @@ -108,22 +108,29 @@ static int __diag_ipl_functions(struct kvm_vcpu *vcpu) > static int __diag_virtio_hypercall(struct kvm_vcpu *vcpu) > { > int ret, idx; > + long cookie; > > /* No virtio-ccw notification? Get out quickly. */ > if (!vcpu->kvm->arch.css_support || > (vcpu->run->s.regs.gprs[1] != KVM_S390_VIRTIO_CCW_NOTIFY)) > return -EOPNOTSUPP; > > + cookie = vcpu->run->s.regs.gprs[4]; Hmm signed so this can become negative. > idx = srcu_read_lock(&vcpu->kvm->srcu); > /* > * The layout is as follows: > * - gpr 2 contains the subchannel id (passed as addr) > * - gpr 3 contains the virtqueue index (passed as datamatch) > + * - gpr 4 contains the index on the bus (optionally) > */ > - ret = kvm_io_bus_write(vcpu->kvm, KVM_VIRTIO_CCW_NOTIFY_BUS, > - vcpu->run->s.regs.gprs[2], > - 8, &vcpu->run->s.regs.gprs[3]); > + ret = kvm_io_bus_write_cookie(vcpu->kvm, KVM_VIRTIO_CCW_NOTIFY_BUS, > + vcpu->run->s.regs.gprs[2], > + 8, &vcpu->run->s.regs.gprs[3], > + &cookie); > srcu_read_unlock(&vcpu->kvm->srcu, idx); > + if (!ret) > + /* Return cookie in gpr 2. */ > + vcpu->run->s.regs.gprs[2] = cookie; We should also set gprs[2] to something sane if exiting to userspace so avoid adding overhead for that case. Probably # of devices + 1 or a negative value. Are there 32 bit guests? If yes can they pass a negative value? > /* kvm_io_bus_write returns -EOPNOTSUPP if it found no match. */ > return ret < 0 ? ret : 0; > } > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h > index 206247f..2f65a3a 100644 > --- a/include/linux/kvm_host.h > +++ b/include/linux/kvm_host.h > @@ -154,6 +154,8 @@ 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 7c188a3..b77ea5f 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -2710,6 +2710,51 @@ 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, > + }; > + > + if (!cookie) > + return -EINVAL; > + Hmm does this ever trigger? > + bus = srcu_dereference(kvm->buses[bus_idx], &kvm->srcu); > + > + /* First try the device referenced by *cookie. */ > + if (kvm_io_bus_sort_cmp(&range, &bus->range[*cookie]) == 0) We need to range-check the cookie. > + 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++; > + } > +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) -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, 5 Mar 2013 15:19:43 +0200 "Michael S. Tsirkin" <mst@redhat.com> wrote: > On Tue, Mar 05, 2013 at 09:13:08AM +0100, Cornelia Huck wrote: > > On Mon, 4 Mar 2013 21:07:41 -0300 > > Marcelo Tosatti <mtosatti@redhat.com> wrote: > > > > > On Thu, Feb 28, 2013 at 12:33:21PM +0100, Cornelia Huck wrote: > > > > Enable ioeventfd support on s390 and hook up diagnose 500 virtio-ccw > > > > notifications. > > > > > > > > Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com> > > > > --- > > > > arch/s390/kvm/Kconfig | 1 + > > > > arch/s390/kvm/Makefile | 2 +- > > > > arch/s390/kvm/diag.c | 26 ++++++++++++++++++++++++++ > > > > arch/s390/kvm/kvm-s390.c | 1 + > > > > 4 files changed, 29 insertions(+), 1 deletion(-) > > > > > > > > diff --git a/arch/s390/kvm/Kconfig b/arch/s390/kvm/Kconfig > > > > index b58dd86..3c43e30 100644 > > > > --- a/arch/s390/kvm/Kconfig > > > > +++ b/arch/s390/kvm/Kconfig > > > > @@ -22,6 +22,7 @@ config KVM > > > > select PREEMPT_NOTIFIERS > > > > select ANON_INODES > > > > select HAVE_KVM_CPU_RELAX_INTERCEPT > > > > + select HAVE_KVM_EVENTFD > > > > ---help--- > > > > Support hosting paravirtualized guest machines using the SIE > > > > virtualization capability on the mainframe. This should work > > > > diff --git a/arch/s390/kvm/Makefile b/arch/s390/kvm/Makefile > > > > index 3975722..8fe9d65 100644 > > > > --- a/arch/s390/kvm/Makefile > > > > +++ b/arch/s390/kvm/Makefile > > > > @@ -6,7 +6,7 @@ > > > > # it under the terms of the GNU General Public License (version 2 only) > > > > # as published by the Free Software Foundation. > > > > > > > > -common-objs = $(addprefix ../../../virt/kvm/, kvm_main.o) > > > > +common-objs = $(addprefix ../../../virt/kvm/, kvm_main.o eventfd.o) > > > > > > > > ccflags-y := -Ivirt/kvm -Iarch/s390/kvm > > > > > > > > diff --git a/arch/s390/kvm/diag.c b/arch/s390/kvm/diag.c > > > > index a390687..1c01a99 100644 > > > > --- a/arch/s390/kvm/diag.c > > > > +++ b/arch/s390/kvm/diag.c > > > > @@ -13,6 +13,7 @@ > > > > > > > > #include <linux/kvm.h> > > > > #include <linux/kvm_host.h> > > > > +#include <asm/virtio-ccw.h> > > > > #include "kvm-s390.h" > > > > #include "trace.h" > > > > #include "trace-s390.h" > > > > @@ -104,6 +105,29 @@ static int __diag_ipl_functions(struct kvm_vcpu *vcpu) > > > > return -EREMOTE; > > > > } > > > > > > > > +static int __diag_virtio_hypercall(struct kvm_vcpu *vcpu) > > > > +{ > > > > + int ret, idx; > > > > + > > > > + /* No virtio-ccw notification? Get out quickly. */ > > > > + if (!vcpu->kvm->arch.css_support || > > > > + (vcpu->run->s.regs.gprs[1] != KVM_S390_VIRTIO_CCW_NOTIFY)) > > > > + return -EOPNOTSUPP; > > > > + > > > > + idx = srcu_read_lock(&vcpu->kvm->srcu); > > > > + /* > > > > + * The layout is as follows: > > > > + * - gpr 2 contains the subchannel id (passed as addr) > > > > + * - gpr 3 contains the virtqueue index (passed as datamatch) > > > > + */ > > > > + ret = kvm_io_bus_write(vcpu->kvm, KVM_VIRTIO_CCW_NOTIFY_BUS, > > > > + vcpu->run->s.regs.gprs[2], > > > > + 8, &vcpu->run->s.regs.gprs[3]); > > > > + srcu_read_unlock(&vcpu->kvm->srcu, idx); > > > > + /* kvm_io_bus_write returns -EOPNOTSUPP if it found no match. */ > > > > + return ret < 0 ? ret : 0; > > > > +} > > > > + > > > > > > What about the cookie? > > > > This is the not-performance-optimized version which went through our > > testing and which I'd like to see applied. I also have a not-yet-tested > > patch that adds cookie support (see below), but I'd like to postpone > > this to 3.10. > > I agree it's best to delay this optimization, focus on basic > functionality now. As guest with cookie support is > compatible with host without said support (all we do > really is reserve a gpr), there won't be issues adding it later. > Some comments on the draft below. > > > > commit 8fce4a8a3478252f7ee2eb74d2732673f5911120 > > Author: Cornelia Huck <cornelia.huck@de.ibm.com> > > Date: Tue Feb 26 17:05:01 2013 +0100 > > > > virtio-ccw: ioeventfd: use cookies > > > > Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com> > > > > diff --git a/arch/s390/kvm/diag.c b/arch/s390/kvm/diag.c > > index 1c01a99..bd2a013 100644 > > --- a/arch/s390/kvm/diag.c > > +++ b/arch/s390/kvm/diag.c > > @@ -108,22 +108,29 @@ static int __diag_ipl_functions(struct kvm_vcpu *vcpu) > > static int __diag_virtio_hypercall(struct kvm_vcpu *vcpu) > > { > > int ret, idx; > > + long cookie; > > > > /* No virtio-ccw notification? Get out quickly. */ > > if (!vcpu->kvm->arch.css_support || > > (vcpu->run->s.regs.gprs[1] != KVM_S390_VIRTIO_CCW_NOTIFY)) > > return -EOPNOTSUPP; > > > > + cookie = vcpu->run->s.regs.gprs[4]; > > Hmm signed so this can become negative. > > > idx = srcu_read_lock(&vcpu->kvm->srcu); > > /* > > * The layout is as follows: > > * - gpr 2 contains the subchannel id (passed as addr) > > * - gpr 3 contains the virtqueue index (passed as datamatch) > > + * - gpr 4 contains the index on the bus (optionally) > > */ > > - ret = kvm_io_bus_write(vcpu->kvm, KVM_VIRTIO_CCW_NOTIFY_BUS, > > - vcpu->run->s.regs.gprs[2], > > - 8, &vcpu->run->s.regs.gprs[3]); > > + ret = kvm_io_bus_write_cookie(vcpu->kvm, KVM_VIRTIO_CCW_NOTIFY_BUS, > > + vcpu->run->s.regs.gprs[2], > > + 8, &vcpu->run->s.regs.gprs[3], > > + &cookie); > > srcu_read_unlock(&vcpu->kvm->srcu, idx); > > + if (!ret) > > + /* Return cookie in gpr 2. */ > > + vcpu->run->s.regs.gprs[2] = cookie; > > We should also set gprs[2] to something sane if exiting to userspace > so avoid adding overhead for that case. > Probably # of devices + 1 or a negative value. Negative value would probably be the most obvious. > Are there 32 bit guests? If yes can they pass a negative value? No, we only support 64 bit guests. > > > /* kvm_io_bus_write returns -EOPNOTSUPP if it found no match. */ > > return ret < 0 ? ret : 0; > > } > > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h > > index 206247f..2f65a3a 100644 > > --- a/include/linux/kvm_host.h > > +++ b/include/linux/kvm_host.h > > @@ -154,6 +154,8 @@ 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 7c188a3..b77ea5f 100644 > > --- a/virt/kvm/kvm_main.c > > +++ b/virt/kvm/kvm_main.c > > @@ -2710,6 +2710,51 @@ 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, > > + }; > > + > > + if (!cookie) > > + return -EINVAL; > > + > > Hmm does this ever trigger? Probably not. > > > + bus = srcu_dereference(kvm->buses[bus_idx], &kvm->srcu); > > + > > + /* First try the device referenced by *cookie. */ > > + if (kvm_io_bus_sort_cmp(&range, &bus->range[*cookie]) == 0) > > We need to range-check the cookie. Yup. > > > + 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++; > > + } > > +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) > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/arch/s390/kvm/diag.c b/arch/s390/kvm/diag.c index 1c01a99..bd2a013 100644 --- a/arch/s390/kvm/diag.c +++ b/arch/s390/kvm/diag.c @@ -108,22 +108,29 @@ static int __diag_ipl_functions(struct kvm_vcpu *vcpu) static int __diag_virtio_hypercall(struct kvm_vcpu *vcpu) { int ret, idx; + long cookie; /* No virtio-ccw notification? Get out quickly. */ if (!vcpu->kvm->arch.css_support || (vcpu->run->s.regs.gprs[1] != KVM_S390_VIRTIO_CCW_NOTIFY)) return -EOPNOTSUPP; + cookie = vcpu->run->s.regs.gprs[4]; idx = srcu_read_lock(&vcpu->kvm->srcu); /* * The layout is as follows: * - gpr 2 contains the subchannel id (passed as addr) * - gpr 3 contains the virtqueue index (passed as datamatch) + * - gpr 4 contains the index on the bus (optionally) */ - ret = kvm_io_bus_write(vcpu->kvm, KVM_VIRTIO_CCW_NOTIFY_BUS, - vcpu->run->s.regs.gprs[2], - 8, &vcpu->run->s.regs.gprs[3]); + ret = kvm_io_bus_write_cookie(vcpu->kvm, KVM_VIRTIO_CCW_NOTIFY_BUS, + vcpu->run->s.regs.gprs[2], + 8, &vcpu->run->s.regs.gprs[3], + &cookie); srcu_read_unlock(&vcpu->kvm->srcu, idx); + if (!ret) + /* Return cookie in gpr 2. */ + vcpu->run->s.regs.gprs[2] = cookie; /* kvm_io_bus_write returns -EOPNOTSUPP if it found no match. */ return ret < 0 ? ret : 0; } diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 206247f..2f65a3a 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -154,6 +154,8 @@ 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 7c188a3..b77ea5f 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -2710,6 +2710,51 @@ 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, + }; + + if (!cookie) + return -EINVAL; + + bus = srcu_dereference(kvm->buses[bus_idx], &kvm->srcu); + + /* First try the device referenced by *cookie. */ + if (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++; + } +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)