| Message ID | 1384924730-22762-1-git-send-email-aik@ozlabs.ru (mailing list archive) |
|---|---|
| State | Changes Requested |
| Headers | show |
On Wed, 2013-11-20 at 16:18 +1100, Alexey Kardashevskiy wrote: > In addition to the external VFIO user API, a VFIO KVM device > has been introduced recently. > > sPAPR TCE IOMMU is para-virtualized and the guest does map/unmap > via hypercalls which take a logical bus id (LIOBN) as a target IOMMU > identifier. LIOBNs are made up and linked to IOMMU groups by the user > space. In order to accelerate IOMMU operations in the KVM, we need > to tell KVM the information about LIOBN-to-group mapping. > > For that, a new KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE_LIOBN parameter > is added. It accepts a pair of a VFIO group fd and LIOBN. > > This also adds a new kvm_vfio_find_group_by_liobn() function which > receives kvm struct, LIOBN and a callback. As it increases the IOMMU > group use counter, the KVMr is required to pass a callback which > called when the VFIO group is about to be removed VFIO-KVM tracking so > the KVM is able to call iommu_group_put() to release the IOMMU group. > > The KVM uses kvm_vfio_find_group_by_liobn() once per KVM run and caches > the result in kvm_arch. iommu_group_put() for all groups will be called > when KVM finishes (in the SPAPR TCE in KVM enablement patch). > > Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> > --- > Changes: > v3: > * total rework > * added a release callback into kvm_vfio_find_group_by_liobn so now > the user of the API can get a notification if the group is about to > disappear > --- > Documentation/virtual/kvm/devices/vfio.txt | 19 ++++- > arch/powerpc/kvm/Kconfig | 1 + > arch/powerpc/kvm/Makefile | 3 + > include/linux/kvm_host.h | 18 +++++ > include/uapi/linux/kvm.h | 7 ++ > virt/kvm/vfio.c | 116 ++++++++++++++++++++++++++++- > 6 files changed, 161 insertions(+), 3 deletions(-) > > diff --git a/Documentation/virtual/kvm/devices/vfio.txt b/Documentation/virtual/kvm/devices/vfio.txt > index ef51740..7ecb3b2 100644 > --- a/Documentation/virtual/kvm/devices/vfio.txt > +++ b/Documentation/virtual/kvm/devices/vfio.txt > @@ -16,7 +16,22 @@ Groups: > > KVM_DEV_VFIO_GROUP attributes: > KVM_DEV_VFIO_GROUP_ADD: Add a VFIO group to VFIO-KVM device tracking > + kvm_device_attr.addr points to an int32_t file descriptor > + for the VFIO group. > + > KVM_DEV_VFIO_GROUP_DEL: Remove a VFIO group from VFIO-KVM device tracking > + kvm_device_attr.addr points to an int32_t file descriptor > + for the VFIO group. > + > + KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE_LIOBN: sets a liobn for a VFIO group > + kvm_device_attr.addr points to a struct: > + struct kvm_vfio_spapr_tce_liobn { > + __u32 argsz; > + __u32 fd; fds are signed, __s32 > + __u32 liobn; > + }; > + where > + @argsz is a struct size; > + @fd is a file descriptor for a VFIO group; > + @liobn is a logical bus id to be associated with the group. > > -For each, kvm_device_attr.addr points to an int32_t file descriptor > -for the VFIO group. > diff --git a/arch/powerpc/kvm/Kconfig b/arch/powerpc/kvm/Kconfig > index 61b3535..d1b7f64 100644 > --- a/arch/powerpc/kvm/Kconfig > +++ b/arch/powerpc/kvm/Kconfig > @@ -60,6 +60,7 @@ config KVM_BOOK3S_64 > select KVM_BOOK3S_64_HANDLER > select KVM > select SPAPR_TCE_IOMMU > + select KVM_VFIO > ---help--- > Support running unmodified book3s_64 and book3s_32 guest kernels > in virtual machines on book3s_64 host processors. > diff --git a/arch/powerpc/kvm/Makefile b/arch/powerpc/kvm/Makefile > index 6646c95..2438d2e 100644 > --- a/arch/powerpc/kvm/Makefile > +++ b/arch/powerpc/kvm/Makefile > @@ -87,6 +87,9 @@ kvm-book3s_64-builtin-objs-$(CONFIG_KVM_BOOK3S_64_HV) := \ > kvm-book3s_64-objs-$(CONFIG_KVM_XICS) += \ > book3s_xics.o > > +kvm-book3s_64-objs-$(CONFIG_KVM_VFIO) += \ > + $(KVM)/vfio.o \ > + > kvm-book3s_64-module-objs := \ > $(KVM)/kvm_main.o \ > $(KVM)/eventfd.o \ > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h > index 88ff96a..1d2ad5e 100644 > --- a/include/linux/kvm_host.h > +++ b/include/linux/kvm_host.h > @@ -1112,5 +1112,23 @@ static inline bool kvm_vcpu_eligible_for_directed_yield(struct kvm_vcpu *vcpu) > } > > #endif /* CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT */ > + > +typedef void (*kvm_vfio_release_group_callback)(struct kvm *kvm, > + unsigned long liobn); liobn was said to be __u32 in kvm_vfio_spapr_tce_liobn above, here it's unsigned long? > + > +#if defined(CONFIG_KVM_VFIO) && defined(CONFIG_SPAPR_TCE_IOMMU) > + > +extern struct iommu_group *kvm_vfio_find_group_by_liobn(struct kvm *kvm, > + unsigned long liobn, kvm_vfio_release_group_callback cb); > + > +#else > + > +static inline struct iommu_group *kvm_vfio_find_group_by_liobn(struct kvm *kvm, > + unsigned long liobn, ikvm_vfio_release_group_callback cb) > +{ > + return NULL; > +} > +#endif /* CONFIG_KVM_VFIO && CONFIG_SPAPR_TCE_IOMMU */ > + > #endif > > diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h > index 7c1a349..3d77dde 100644 > --- a/include/uapi/linux/kvm.h > +++ b/include/uapi/linux/kvm.h > @@ -847,6 +847,13 @@ struct kvm_device_attr { > #define KVM_DEV_VFIO_GROUP 1 > #define KVM_DEV_VFIO_GROUP_ADD 1 > #define KVM_DEV_VFIO_GROUP_DEL 2 > +#define KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE_LIOBN 3 > + > +struct kvm_vfio_spapr_tce_liobn { > + __u32 argsz; > + __u32 fd; > + __u32 liobn; > +}; > > /* > * ioctls for VM fds > diff --git a/virt/kvm/vfio.c b/virt/kvm/vfio.c > index ca4260e..448910d 100644 > --- a/virt/kvm/vfio.c > +++ b/virt/kvm/vfio.c > @@ -22,6 +22,12 @@ > struct kvm_vfio_group { > struct list_head node; > struct vfio_group *vfio_group; > +#ifdef CONFIG_SPAPR_TCE_IOMMU > + struct { > + unsigned long liobn; > + kvm_vfio_release_group_callback cb; > + } spapr_tce; > +#endif > }; > > struct kvm_vfio { > @@ -59,6 +65,51 @@ static void kvm_vfio_group_put_external_user(struct vfio_group *vfio_group) > symbol_put(vfio_group_put_external_user); > } > > +#ifdef CONFIG_SPAPR_TCE_IOMMU > +struct iommu_group *kvm_vfio_find_group_by_liobn(struct kvm *kvm, > + unsigned long liobn, kvm_vfio_release_group_callback cb) > +{ > + struct kvm_vfio_group *kvg; > + int group_id; > + struct iommu_group *grp; > + struct kvm_vfio *kv = NULL; > + struct kvm_device *tmp; > + > + if (!cb) > + return NULL; Is it worthwhile to use ERR_PTR(-EINVAL) here and the caller can use IS_ERR()? > + > + /* Find a VFIO KVM device */ > + list_for_each_entry(tmp, &kvm->devices, vm_node) { > + if (tmp->ops != &kvm_vfio_ops) > + continue; > + > + kv = tmp->private; > + break; > + } > + > + if (!kv) > + return NULL; ERR_PTR(-EFAULT)? EIO? > + > + /* Find a group */ Still ignoring kv->lock > + list_for_each_entry(kvg, &kv->group_list, node) { > + if (kvg->spapr_tce.liobn != liobn) > + continue; > + > + if (kvg->spapr_tce.cb) > + return NULL; ERR_PTR(-EBUSY)? > + > + kvg->spapr_tce.cb = cb; > + group_id = vfio_external_user_iommu_id(kvg->vfio_group); > + grp = iommu_group_get_by_id(group_id); > + > + return grp; > + } > + > + return NULL; ERR_PTR(-ENODEV)? > +} > +EXPORT_SYMBOL_GPL(kvm_vfio_find_group_by_liobn); > +#endif > + > /* > * Groups can use the same or different IOMMU domains. If the same then > * adding a new group may change the coherency of groups we've previously > @@ -170,6 +221,11 @@ static int kvm_vfio_set_group(struct kvm_device *dev, long attr, u64 arg) > continue; > > list_del(&kvg->node); > +#ifdef CONFIG_SPAPR_TCE_IOMMU > + if (kvg->spapr_tce.cb) > + kvg->spapr_tce.cb(dev->kvm, > + kvg->spapr_tce.liobn); > +#endif > kvm_vfio_group_put_external_user(kvg->vfio_group); > kfree(kvg); > ret = 0; > @@ -183,6 +239,62 @@ static int kvm_vfio_set_group(struct kvm_device *dev, long attr, u64 arg) > kvm_vfio_update_coherency(dev); > > return ret; > + > +#ifdef CONFIG_SPAPR_TCE_IOMMU > + case KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE_LIOBN: { > + struct kvm_vfio_spapr_tce_liobn param; > + unsigned long minsz; > + struct kvm_vfio *kv = dev->private; > + struct vfio_group *vfio_group; > + struct kvm_vfio_group *kvg; > + struct fd f; > + > + minsz = offsetofend(struct kvm_vfio_spapr_tce_liobn, liobn); > + > + if (copy_from_user(¶m, (void __user *)arg, minsz)) > + return -EFAULT; > + > + if (param.argsz < minsz) > + return -EINVAL; > + > + if (copy_from_user(¶m, (void __user *)arg, minsz)) > + return -EFAULT; copy_from_user twice? Extra copy here? > + > + f = fdget(param.fd); > + if (!f.file) > + return -EBADF; > + > + vfio_group = kvm_vfio_group_get_external_user(f.file); > + fdput(f); > + > + if (IS_ERR(vfio_group)) > + return PTR_ERR(vfio_group); > + > + ret = -ENOENT; > + > + mutex_lock(&kv->lock); > + > + list_for_each_entry(kvg, &kv->group_list, node) { > + if (kvg->vfio_group != vfio_group) > + continue; > + > + if (kvg->spapr_tce.liobn) { > + ret = -EBUSY; > + break; > + } Is zero not an liobn that can be used by userspace? Is it intentional that there's no way to unset or change the group/liobn mapping? Thanks, Alex > + > + kvg->spapr_tce.liobn = param.liobn; > + ret = 0; > + break; > + } > + > + mutex_unlock(&kv->lock); > + > + kvm_vfio_group_put_external_user(vfio_group); > + > + return ret; > + } > +#endif /* CONFIG_SPAPR_TCE_IOMMU */ > } > > return -ENXIO; > @@ -207,9 +319,11 @@ static int kvm_vfio_has_attr(struct kvm_device *dev, > switch (attr->attr) { > case KVM_DEV_VFIO_GROUP_ADD: > case KVM_DEV_VFIO_GROUP_DEL: > +#ifdef CONFIG_SPAPR_TCE_IOMMU > + case KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE_LIOBN: > +#endif > return 0; > } > - > break; > } >
On 11/21/2013 07:57 AM, Alex Williamson wrote: > On Wed, 2013-11-20 at 16:18 +1100, Alexey Kardashevskiy wrote: >> In addition to the external VFIO user API, a VFIO KVM device >> has been introduced recently. >> >> sPAPR TCE IOMMU is para-virtualized and the guest does map/unmap >> via hypercalls which take a logical bus id (LIOBN) as a target IOMMU >> identifier. LIOBNs are made up and linked to IOMMU groups by the user >> space. In order to accelerate IOMMU operations in the KVM, we need >> to tell KVM the information about LIOBN-to-group mapping. >> >> For that, a new KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE_LIOBN parameter >> is added. It accepts a pair of a VFIO group fd and LIOBN. >> >> This also adds a new kvm_vfio_find_group_by_liobn() function which >> receives kvm struct, LIOBN and a callback. As it increases the IOMMU >> group use counter, the KVMr is required to pass a callback which >> called when the VFIO group is about to be removed VFIO-KVM tracking so >> the KVM is able to call iommu_group_put() to release the IOMMU group. >> >> The KVM uses kvm_vfio_find_group_by_liobn() once per KVM run and caches >> the result in kvm_arch. iommu_group_put() for all groups will be called >> when KVM finishes (in the SPAPR TCE in KVM enablement patch). >> >> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> >> --- >> Changes: >> v3: >> * total rework >> * added a release callback into kvm_vfio_find_group_by_liobn so now >> the user of the API can get a notification if the group is about to >> disappear >> --- >> Documentation/virtual/kvm/devices/vfio.txt | 19 ++++- >> arch/powerpc/kvm/Kconfig | 1 + >> arch/powerpc/kvm/Makefile | 3 + >> include/linux/kvm_host.h | 18 +++++ >> include/uapi/linux/kvm.h | 7 ++ >> virt/kvm/vfio.c | 116 ++++++++++++++++++++++++++++- >> 6 files changed, 161 insertions(+), 3 deletions(-) >> >> diff --git a/Documentation/virtual/kvm/devices/vfio.txt b/Documentation/virtual/kvm/devices/vfio.txt >> index ef51740..7ecb3b2 100644 >> --- a/Documentation/virtual/kvm/devices/vfio.txt >> +++ b/Documentation/virtual/kvm/devices/vfio.txt >> @@ -16,7 +16,22 @@ Groups: >> >> KVM_DEV_VFIO_GROUP attributes: >> KVM_DEV_VFIO_GROUP_ADD: Add a VFIO group to VFIO-KVM device tracking >> + kvm_device_attr.addr points to an int32_t file descriptor >> + for the VFIO group. >> + >> KVM_DEV_VFIO_GROUP_DEL: Remove a VFIO group from VFIO-KVM device tracking >> + kvm_device_attr.addr points to an int32_t file descriptor >> + for the VFIO group. >> + >> + KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE_LIOBN: sets a liobn for a VFIO group >> + kvm_device_attr.addr points to a struct: >> + struct kvm_vfio_spapr_tce_liobn { >> + __u32 argsz; >> + __u32 fd; > > fds are signed, __s32 > >> + __u32 liobn; >> + }; >> + where >> + @argsz is a struct size; >> + @fd is a file descriptor for a VFIO group; >> + @liobn is a logical bus id to be associated with the group. >> >> -For each, kvm_device_attr.addr points to an int32_t file descriptor >> -for the VFIO group. >> diff --git a/arch/powerpc/kvm/Kconfig b/arch/powerpc/kvm/Kconfig >> index 61b3535..d1b7f64 100644 >> --- a/arch/powerpc/kvm/Kconfig >> +++ b/arch/powerpc/kvm/Kconfig >> @@ -60,6 +60,7 @@ config KVM_BOOK3S_64 >> select KVM_BOOK3S_64_HANDLER >> select KVM >> select SPAPR_TCE_IOMMU >> + select KVM_VFIO >> ---help--- >> Support running unmodified book3s_64 and book3s_32 guest kernels >> in virtual machines on book3s_64 host processors. >> diff --git a/arch/powerpc/kvm/Makefile b/arch/powerpc/kvm/Makefile >> index 6646c95..2438d2e 100644 >> --- a/arch/powerpc/kvm/Makefile >> +++ b/arch/powerpc/kvm/Makefile >> @@ -87,6 +87,9 @@ kvm-book3s_64-builtin-objs-$(CONFIG_KVM_BOOK3S_64_HV) := \ >> kvm-book3s_64-objs-$(CONFIG_KVM_XICS) += \ >> book3s_xics.o >> >> +kvm-book3s_64-objs-$(CONFIG_KVM_VFIO) += \ >> + $(KVM)/vfio.o \ >> + >> kvm-book3s_64-module-objs := \ >> $(KVM)/kvm_main.o \ >> $(KVM)/eventfd.o \ >> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h >> index 88ff96a..1d2ad5e 100644 >> --- a/include/linux/kvm_host.h >> +++ b/include/linux/kvm_host.h >> @@ -1112,5 +1112,23 @@ static inline bool kvm_vcpu_eligible_for_directed_yield(struct kvm_vcpu *vcpu) >> } >> >> #endif /* CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT */ >> + >> +typedef void (*kvm_vfio_release_group_callback)(struct kvm *kvm, >> + unsigned long liobn); > > liobn was said to be __u32 in kvm_vfio_spapr_tce_liobn above, here it's > unsigned long? PAPR spec says it is 32 bit and kvm_vfio_spapr_tce_liobn is a binary interface (ABI?) so I want it to be precise. However kvmppc_get_gpr() (used to parse hypercall parameters such as liobn) return unsigned long. So inside the kernel I use unsigned long. So what does make sense to change here? > >> + >> +#if defined(CONFIG_KVM_VFIO) && defined(CONFIG_SPAPR_TCE_IOMMU) >> + >> +extern struct iommu_group *kvm_vfio_find_group_by_liobn(struct kvm *kvm, >> + unsigned long liobn, kvm_vfio_release_group_callback cb); >> + >> +#else >> + >> +static inline struct iommu_group *kvm_vfio_find_group_by_liobn(struct kvm *kvm, >> + unsigned long liobn, ikvm_vfio_release_group_callback cb) >> +{ >> + return NULL; >> +} >> +#endif /* CONFIG_KVM_VFIO && CONFIG_SPAPR_TCE_IOMMU */ >> + >> #endif >> >> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h >> index 7c1a349..3d77dde 100644 >> --- a/include/uapi/linux/kvm.h >> +++ b/include/uapi/linux/kvm.h >> @@ -847,6 +847,13 @@ struct kvm_device_attr { >> #define KVM_DEV_VFIO_GROUP 1 >> #define KVM_DEV_VFIO_GROUP_ADD 1 >> #define KVM_DEV_VFIO_GROUP_DEL 2 >> +#define KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE_LIOBN 3 >> + >> +struct kvm_vfio_spapr_tce_liobn { >> + __u32 argsz; >> + __u32 fd; >> + __u32 liobn; >> +}; >> >> /* >> * ioctls for VM fds >> diff --git a/virt/kvm/vfio.c b/virt/kvm/vfio.c >> index ca4260e..448910d 100644 >> --- a/virt/kvm/vfio.c >> +++ b/virt/kvm/vfio.c >> @@ -22,6 +22,12 @@ >> struct kvm_vfio_group { >> struct list_head node; >> struct vfio_group *vfio_group; >> +#ifdef CONFIG_SPAPR_TCE_IOMMU >> + struct { >> + unsigned long liobn; >> + kvm_vfio_release_group_callback cb; >> + } spapr_tce; >> +#endif >> }; >> >> struct kvm_vfio { >> @@ -59,6 +65,51 @@ static void kvm_vfio_group_put_external_user(struct vfio_group *vfio_group) >> symbol_put(vfio_group_put_external_user); >> } >> >> +#ifdef CONFIG_SPAPR_TCE_IOMMU >> +struct iommu_group *kvm_vfio_find_group_by_liobn(struct kvm *kvm, >> + unsigned long liobn, kvm_vfio_release_group_callback cb) >> +{ >> + struct kvm_vfio_group *kvg; >> + int group_id; >> + struct iommu_group *grp; >> + struct kvm_vfio *kv = NULL; >> + struct kvm_device *tmp; >> + >> + if (!cb) >> + return NULL; > > Is it worthwhile to use ERR_PTR(-EINVAL) here and the caller can use > IS_ERR()? > >> + >> + /* Find a VFIO KVM device */ >> + list_for_each_entry(tmp, &kvm->devices, vm_node) { >> + if (tmp->ops != &kvm_vfio_ops) >> + continue; >> + >> + kv = tmp->private; >> + break; >> + } >> + >> + if (!kv) >> + return NULL; > > ERR_PTR(-EFAULT)? EIO? > >> + >> + /* Find a group */ > > Still ignoring kv->lock > >> + list_for_each_entry(kvg, &kv->group_list, node) { >> + if (kvg->spapr_tce.liobn != liobn) >> + continue; >> + >> + if (kvg->spapr_tce.cb) >> + return NULL; > > ERR_PTR(-EBUSY)? > >> + >> + kvg->spapr_tce.cb = cb; >> + group_id = vfio_external_user_iommu_id(kvg->vfio_group); >> + grp = iommu_group_get_by_id(group_id); >> + >> + return grp; >> + } >> + >> + return NULL; > > ERR_PTR(-ENODEV)? > >> +} >> +EXPORT_SYMBOL_GPL(kvm_vfio_find_group_by_liobn); >> +#endif >> + >> /* >> * Groups can use the same or different IOMMU domains. If the same then >> * adding a new group may change the coherency of groups we've previously >> @@ -170,6 +221,11 @@ static int kvm_vfio_set_group(struct kvm_device *dev, long attr, u64 arg) >> continue; >> >> list_del(&kvg->node); >> +#ifdef CONFIG_SPAPR_TCE_IOMMU >> + if (kvg->spapr_tce.cb) >> + kvg->spapr_tce.cb(dev->kvm, >> + kvg->spapr_tce.liobn); >> +#endif >> kvm_vfio_group_put_external_user(kvg->vfio_group); >> kfree(kvg); >> ret = 0; >> @@ -183,6 +239,62 @@ static int kvm_vfio_set_group(struct kvm_device *dev, long attr, u64 arg) >> kvm_vfio_update_coherency(dev); >> >> return ret; >> + >> +#ifdef CONFIG_SPAPR_TCE_IOMMU >> + case KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE_LIOBN: { >> + struct kvm_vfio_spapr_tce_liobn param; >> + unsigned long minsz; >> + struct kvm_vfio *kv = dev->private; >> + struct vfio_group *vfio_group; >> + struct kvm_vfio_group *kvg; >> + struct fd f; >> + >> + minsz = offsetofend(struct kvm_vfio_spapr_tce_liobn, liobn); >> + >> + if (copy_from_user(¶m, (void __user *)arg, minsz)) >> + return -EFAULT; >> + >> + if (param.argsz < minsz) >> + return -EINVAL; >> + >> + if (copy_from_user(¶m, (void __user *)arg, minsz)) >> + return -EFAULT; > > copy_from_user twice? Extra copy here? Oh. All I wanted was to read minsz first but I cut-n-pasted too blindely :) > >> + >> + f = fdget(param.fd); >> + if (!f.file) >> + return -EBADF; >> + >> + vfio_group = kvm_vfio_group_get_external_user(f.file); >> + fdput(f); >> + >> + if (IS_ERR(vfio_group)) >> + return PTR_ERR(vfio_group); >> + >> + ret = -ENOENT; >> + >> + mutex_lock(&kv->lock); >> + >> + list_for_each_entry(kvg, &kv->group_list, node) { >> + if (kvg->vfio_group != vfio_group) >> + continue; >> + >> + if (kvg->spapr_tce.liobn) { >> + ret = -EBUSY; >> + break; >> + } > > Is zero not an liobn that can be used by userspace? Good point, thanks. I thought zero cannot be used but by spec -1 is reserved > Is it intentional > that there's no way to unset or change the group/liobn mapping? Thanks, I do not see why we would want to disable once enabled acceleration. Group removal should clear it though so we are good. Thanks for the review and patience :) > > Alex > >> + >> + kvg->spapr_tce.liobn = param.liobn; >> + ret = 0; >> + break; >> + } >> + >> + mutex_unlock(&kv->lock); >> + >> + kvm_vfio_group_put_external_user(vfio_group); >> + >> + return ret; >> + } >> +#endif /* CONFIG_SPAPR_TCE_IOMMU */ >> } >> >> return -ENXIO; >> @@ -207,9 +319,11 @@ static int kvm_vfio_has_attr(struct kvm_device *dev, >> switch (attr->attr) { >> case KVM_DEV_VFIO_GROUP_ADD: >> case KVM_DEV_VFIO_GROUP_DEL: >> +#ifdef CONFIG_SPAPR_TCE_IOMMU >> + case KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE_LIOBN: >> +#endif >> return 0; >> } >> - >> break; >> } >> > > >
On Thu, 2013-11-21 at 12:22 +1100, Alexey Kardashevskiy wrote: > On 11/21/2013 07:57 AM, Alex Williamson wrote: > > On Wed, 2013-11-20 at 16:18 +1100, Alexey Kardashevskiy wrote: > >> In addition to the external VFIO user API, a VFIO KVM device > >> has been introduced recently. > >> > >> sPAPR TCE IOMMU is para-virtualized and the guest does map/unmap > >> via hypercalls which take a logical bus id (LIOBN) as a target IOMMU > >> identifier. LIOBNs are made up and linked to IOMMU groups by the user > >> space. In order to accelerate IOMMU operations in the KVM, we need > >> to tell KVM the information about LIOBN-to-group mapping. > >> > >> For that, a new KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE_LIOBN parameter > >> is added. It accepts a pair of a VFIO group fd and LIOBN. > >> > >> This also adds a new kvm_vfio_find_group_by_liobn() function which > >> receives kvm struct, LIOBN and a callback. As it increases the IOMMU > >> group use counter, the KVMr is required to pass a callback which > >> called when the VFIO group is about to be removed VFIO-KVM tracking so > >> the KVM is able to call iommu_group_put() to release the IOMMU group. > >> > >> The KVM uses kvm_vfio_find_group_by_liobn() once per KVM run and caches > >> the result in kvm_arch. iommu_group_put() for all groups will be called > >> when KVM finishes (in the SPAPR TCE in KVM enablement patch). > >> > >> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> > >> --- > >> Changes: > >> v3: > >> * total rework > >> * added a release callback into kvm_vfio_find_group_by_liobn so now > >> the user of the API can get a notification if the group is about to > >> disappear > >> --- > >> Documentation/virtual/kvm/devices/vfio.txt | 19 ++++- > >> arch/powerpc/kvm/Kconfig | 1 + > >> arch/powerpc/kvm/Makefile | 3 + > >> include/linux/kvm_host.h | 18 +++++ > >> include/uapi/linux/kvm.h | 7 ++ > >> virt/kvm/vfio.c | 116 ++++++++++++++++++++++++++++- > >> 6 files changed, 161 insertions(+), 3 deletions(-) > >> > >> diff --git a/Documentation/virtual/kvm/devices/vfio.txt b/Documentation/virtual/kvm/devices/vfio.txt > >> index ef51740..7ecb3b2 100644 > >> --- a/Documentation/virtual/kvm/devices/vfio.txt > >> +++ b/Documentation/virtual/kvm/devices/vfio.txt > >> @@ -16,7 +16,22 @@ Groups: > >> > >> KVM_DEV_VFIO_GROUP attributes: > >> KVM_DEV_VFIO_GROUP_ADD: Add a VFIO group to VFIO-KVM device tracking > >> + kvm_device_attr.addr points to an int32_t file descriptor > >> + for the VFIO group. > >> + > >> KVM_DEV_VFIO_GROUP_DEL: Remove a VFIO group from VFIO-KVM device tracking > >> + kvm_device_attr.addr points to an int32_t file descriptor > >> + for the VFIO group. > >> + > >> + KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE_LIOBN: sets a liobn for a VFIO group > >> + kvm_device_attr.addr points to a struct: > >> + struct kvm_vfio_spapr_tce_liobn { > >> + __u32 argsz; > >> + __u32 fd; > > > > fds are signed, __s32 > > > >> + __u32 liobn; > >> + }; > >> + where > >> + @argsz is a struct size; > >> + @fd is a file descriptor for a VFIO group; > >> + @liobn is a logical bus id to be associated with the group. > >> > >> -For each, kvm_device_attr.addr points to an int32_t file descriptor > >> -for the VFIO group. > >> diff --git a/arch/powerpc/kvm/Kconfig b/arch/powerpc/kvm/Kconfig > >> index 61b3535..d1b7f64 100644 > >> --- a/arch/powerpc/kvm/Kconfig > >> +++ b/arch/powerpc/kvm/Kconfig > >> @@ -60,6 +60,7 @@ config KVM_BOOK3S_64 > >> select KVM_BOOK3S_64_HANDLER > >> select KVM > >> select SPAPR_TCE_IOMMU > >> + select KVM_VFIO > >> ---help--- > >> Support running unmodified book3s_64 and book3s_32 guest kernels > >> in virtual machines on book3s_64 host processors. > >> diff --git a/arch/powerpc/kvm/Makefile b/arch/powerpc/kvm/Makefile > >> index 6646c95..2438d2e 100644 > >> --- a/arch/powerpc/kvm/Makefile > >> +++ b/arch/powerpc/kvm/Makefile > >> @@ -87,6 +87,9 @@ kvm-book3s_64-builtin-objs-$(CONFIG_KVM_BOOK3S_64_HV) := \ > >> kvm-book3s_64-objs-$(CONFIG_KVM_XICS) += \ > >> book3s_xics.o > >> > >> +kvm-book3s_64-objs-$(CONFIG_KVM_VFIO) += \ > >> + $(KVM)/vfio.o \ > >> + > >> kvm-book3s_64-module-objs := \ > >> $(KVM)/kvm_main.o \ > >> $(KVM)/eventfd.o \ > >> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h > >> index 88ff96a..1d2ad5e 100644 > >> --- a/include/linux/kvm_host.h > >> +++ b/include/linux/kvm_host.h > >> @@ -1112,5 +1112,23 @@ static inline bool kvm_vcpu_eligible_for_directed_yield(struct kvm_vcpu *vcpu) > >> } > >> > >> #endif /* CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT */ > >> + > >> +typedef void (*kvm_vfio_release_group_callback)(struct kvm *kvm, > >> + unsigned long liobn); > > > > liobn was said to be __u32 in kvm_vfio_spapr_tce_liobn above, here it's > > unsigned long? > > > PAPR spec says it is 32 bit and kvm_vfio_spapr_tce_liobn is a binary > interface (ABI?) so I want it to be precise. > > However kvmppc_get_gpr() (used to parse hypercall parameters such as liobn) > return unsigned long. So inside the kernel I use unsigned long. > > So what does make sense to change here? Perhaps nothing if that's clear to those familiar with PAPR. Thanks, Alex > > > >> + > >> +#if defined(CONFIG_KVM_VFIO) && defined(CONFIG_SPAPR_TCE_IOMMU) > >> + > >> +extern struct iommu_group *kvm_vfio_find_group_by_liobn(struct kvm *kvm, > >> + unsigned long liobn, kvm_vfio_release_group_callback cb); > >> + > >> +#else > >> + > >> +static inline struct iommu_group *kvm_vfio_find_group_by_liobn(struct kvm *kvm, > >> + unsigned long liobn, ikvm_vfio_release_group_callback cb) > >> +{ > >> + return NULL; > >> +} > >> +#endif /* CONFIG_KVM_VFIO && CONFIG_SPAPR_TCE_IOMMU */ > >> + > >> #endif > >> > >> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h > >> index 7c1a349..3d77dde 100644 > >> --- a/include/uapi/linux/kvm.h > >> +++ b/include/uapi/linux/kvm.h > >> @@ -847,6 +847,13 @@ struct kvm_device_attr { > >> #define KVM_DEV_VFIO_GROUP 1 > >> #define KVM_DEV_VFIO_GROUP_ADD 1 > >> #define KVM_DEV_VFIO_GROUP_DEL 2 > >> +#define KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE_LIOBN 3 > >> + > >> +struct kvm_vfio_spapr_tce_liobn { > >> + __u32 argsz; > >> + __u32 fd; > >> + __u32 liobn; > >> +}; > >> > >> /* > >> * ioctls for VM fds > >> diff --git a/virt/kvm/vfio.c b/virt/kvm/vfio.c > >> index ca4260e..448910d 100644 > >> --- a/virt/kvm/vfio.c > >> +++ b/virt/kvm/vfio.c > >> @@ -22,6 +22,12 @@ > >> struct kvm_vfio_group { > >> struct list_head node; > >> struct vfio_group *vfio_group; > >> +#ifdef CONFIG_SPAPR_TCE_IOMMU > >> + struct { > >> + unsigned long liobn; > >> + kvm_vfio_release_group_callback cb; > >> + } spapr_tce; > >> +#endif > >> }; > >> > >> struct kvm_vfio { > >> @@ -59,6 +65,51 @@ static void kvm_vfio_group_put_external_user(struct vfio_group *vfio_group) > >> symbol_put(vfio_group_put_external_user); > >> } > >> > >> +#ifdef CONFIG_SPAPR_TCE_IOMMU > >> +struct iommu_group *kvm_vfio_find_group_by_liobn(struct kvm *kvm, > >> + unsigned long liobn, kvm_vfio_release_group_callback cb) > >> +{ > >> + struct kvm_vfio_group *kvg; > >> + int group_id; > >> + struct iommu_group *grp; > >> + struct kvm_vfio *kv = NULL; > >> + struct kvm_device *tmp; > >> + > >> + if (!cb) > >> + return NULL; > > > > Is it worthwhile to use ERR_PTR(-EINVAL) here and the caller can use > > IS_ERR()? > > > >> + > >> + /* Find a VFIO KVM device */ > >> + list_for_each_entry(tmp, &kvm->devices, vm_node) { > >> + if (tmp->ops != &kvm_vfio_ops) > >> + continue; > >> + > >> + kv = tmp->private; > >> + break; > >> + } > >> + > >> + if (!kv) > >> + return NULL; > > > > ERR_PTR(-EFAULT)? EIO? > > > >> + > >> + /* Find a group */ > > > > Still ignoring kv->lock > > > >> + list_for_each_entry(kvg, &kv->group_list, node) { > >> + if (kvg->spapr_tce.liobn != liobn) > >> + continue; > >> + > >> + if (kvg->spapr_tce.cb) > >> + return NULL; > > > > ERR_PTR(-EBUSY)? > > > >> + > >> + kvg->spapr_tce.cb = cb; > >> + group_id = vfio_external_user_iommu_id(kvg->vfio_group); > >> + grp = iommu_group_get_by_id(group_id); > >> + > >> + return grp; > >> + } > >> + > >> + return NULL; > > > > ERR_PTR(-ENODEV)? > > > >> +} > >> +EXPORT_SYMBOL_GPL(kvm_vfio_find_group_by_liobn); > >> +#endif > >> + > >> /* > >> * Groups can use the same or different IOMMU domains. If the same then > >> * adding a new group may change the coherency of groups we've previously > >> @@ -170,6 +221,11 @@ static int kvm_vfio_set_group(struct kvm_device *dev, long attr, u64 arg) > >> continue; > >> > >> list_del(&kvg->node); > >> +#ifdef CONFIG_SPAPR_TCE_IOMMU > >> + if (kvg->spapr_tce.cb) > >> + kvg->spapr_tce.cb(dev->kvm, > >> + kvg->spapr_tce.liobn); > >> +#endif > >> kvm_vfio_group_put_external_user(kvg->vfio_group); > >> kfree(kvg); > >> ret = 0; > >> @@ -183,6 +239,62 @@ static int kvm_vfio_set_group(struct kvm_device *dev, long attr, u64 arg) > >> kvm_vfio_update_coherency(dev); > >> > >> return ret; > >> + > >> +#ifdef CONFIG_SPAPR_TCE_IOMMU > >> + case KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE_LIOBN: { > >> + struct kvm_vfio_spapr_tce_liobn param; > >> + unsigned long minsz; > >> + struct kvm_vfio *kv = dev->private; > >> + struct vfio_group *vfio_group; > >> + struct kvm_vfio_group *kvg; > >> + struct fd f; > >> + > >> + minsz = offsetofend(struct kvm_vfio_spapr_tce_liobn, liobn); > >> + > >> + if (copy_from_user(¶m, (void __user *)arg, minsz)) > >> + return -EFAULT; > >> + > >> + if (param.argsz < minsz) > >> + return -EINVAL; > >> + > >> + if (copy_from_user(¶m, (void __user *)arg, minsz)) > >> + return -EFAULT; > > > > copy_from_user twice? Extra copy here? > > > Oh. All I wanted was to read minsz first but I cut-n-pasted too blindely :) > > > > >> + > >> + f = fdget(param.fd); > >> + if (!f.file) > >> + return -EBADF; > >> + > >> + vfio_group = kvm_vfio_group_get_external_user(f.file); > >> + fdput(f); > >> + > >> + if (IS_ERR(vfio_group)) > >> + return PTR_ERR(vfio_group); > >> + > >> + ret = -ENOENT; > >> + > >> + mutex_lock(&kv->lock); > >> + > >> + list_for_each_entry(kvg, &kv->group_list, node) { > >> + if (kvg->vfio_group != vfio_group) > >> + continue; > >> + > >> + if (kvg->spapr_tce.liobn) { > >> + ret = -EBUSY; > >> + break; > >> + } > > > > Is zero not an liobn that can be used by userspace? > > Good point, thanks. I thought zero cannot be used but by spec -1 is reserved > > > > Is it intentional > > that there's no way to unset or change the group/liobn mapping? Thanks, > > > I do not see why we would want to disable once enabled acceleration. Group > removal should clear it though so we are good. > > Thanks for the review and patience :) > > > > > > Alex > > > >> + > >> + kvg->spapr_tce.liobn = param.liobn; > >> + ret = 0; > >> + break; > >> + } > >> + > >> + mutex_unlock(&kv->lock); > >> + > >> + kvm_vfio_group_put_external_user(vfio_group); > >> + > >> + return ret; > >> + } > >> +#endif /* CONFIG_SPAPR_TCE_IOMMU */ > >> } > >> > >> return -ENXIO; > >> @@ -207,9 +319,11 @@ static int kvm_vfio_has_attr(struct kvm_device *dev, > >> switch (attr->attr) { > >> case KVM_DEV_VFIO_GROUP_ADD: > >> case KVM_DEV_VFIO_GROUP_DEL: > >> +#ifdef CONFIG_SPAPR_TCE_IOMMU > >> + case KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE_LIOBN: > >> +#endif > >> return 0; > >> } > >> - > >> break; > >> } > >> > > > > > > > >
diff --git a/Documentation/virtual/kvm/devices/vfio.txt b/Documentation/virtual/kvm/devices/vfio.txt index ef51740..7ecb3b2 100644 --- a/Documentation/virtual/kvm/devices/vfio.txt +++ b/Documentation/virtual/kvm/devices/vfio.txt @@ -16,7 +16,22 @@ Groups: KVM_DEV_VFIO_GROUP attributes: KVM_DEV_VFIO_GROUP_ADD: Add a VFIO group to VFIO-KVM device tracking + kvm_device_attr.addr points to an int32_t file descriptor + for the VFIO group. + KVM_DEV_VFIO_GROUP_DEL: Remove a VFIO group from VFIO-KVM device tracking + kvm_device_attr.addr points to an int32_t file descriptor + for the VFIO group. + + KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE_LIOBN: sets a liobn for a VFIO group + kvm_device_attr.addr points to a struct: + struct kvm_vfio_spapr_tce_liobn { + __u32 argsz; + __u32 fd; + __u32 liobn; + }; + where + @argsz is a struct size; + @fd is a file descriptor for a VFIO group; + @liobn is a logical bus id to be associated with the group. -For each, kvm_device_attr.addr points to an int32_t file descriptor -for the VFIO group. diff --git a/arch/powerpc/kvm/Kconfig b/arch/powerpc/kvm/Kconfig index 61b3535..d1b7f64 100644 --- a/arch/powerpc/kvm/Kconfig +++ b/arch/powerpc/kvm/Kconfig @@ -60,6 +60,7 @@ config KVM_BOOK3S_64 select KVM_BOOK3S_64_HANDLER select KVM select SPAPR_TCE_IOMMU + select KVM_VFIO ---help--- Support running unmodified book3s_64 and book3s_32 guest kernels in virtual machines on book3s_64 host processors. diff --git a/arch/powerpc/kvm/Makefile b/arch/powerpc/kvm/Makefile index 6646c95..2438d2e 100644 --- a/arch/powerpc/kvm/Makefile +++ b/arch/powerpc/kvm/Makefile @@ -87,6 +87,9 @@ kvm-book3s_64-builtin-objs-$(CONFIG_KVM_BOOK3S_64_HV) := \ kvm-book3s_64-objs-$(CONFIG_KVM_XICS) += \ book3s_xics.o +kvm-book3s_64-objs-$(CONFIG_KVM_VFIO) += \ + $(KVM)/vfio.o \ + kvm-book3s_64-module-objs := \ $(KVM)/kvm_main.o \ $(KVM)/eventfd.o \ diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 88ff96a..1d2ad5e 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -1112,5 +1112,23 @@ static inline bool kvm_vcpu_eligible_for_directed_yield(struct kvm_vcpu *vcpu) } #endif /* CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT */ + +typedef void (*kvm_vfio_release_group_callback)(struct kvm *kvm, + unsigned long liobn); + +#if defined(CONFIG_KVM_VFIO) && defined(CONFIG_SPAPR_TCE_IOMMU) + +extern struct iommu_group *kvm_vfio_find_group_by_liobn(struct kvm *kvm, + unsigned long liobn, kvm_vfio_release_group_callback cb); + +#else + +static inline struct iommu_group *kvm_vfio_find_group_by_liobn(struct kvm *kvm, + unsigned long liobn, ikvm_vfio_release_group_callback cb) +{ + return NULL; +} +#endif /* CONFIG_KVM_VFIO && CONFIG_SPAPR_TCE_IOMMU */ + #endif diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index 7c1a349..3d77dde 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -847,6 +847,13 @@ struct kvm_device_attr { #define KVM_DEV_VFIO_GROUP 1 #define KVM_DEV_VFIO_GROUP_ADD 1 #define KVM_DEV_VFIO_GROUP_DEL 2 +#define KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE_LIOBN 3 + +struct kvm_vfio_spapr_tce_liobn { + __u32 argsz; + __u32 fd; + __u32 liobn; +}; /* * ioctls for VM fds diff --git a/virt/kvm/vfio.c b/virt/kvm/vfio.c index ca4260e..448910d 100644 --- a/virt/kvm/vfio.c +++ b/virt/kvm/vfio.c @@ -22,6 +22,12 @@ struct kvm_vfio_group { struct list_head node; struct vfio_group *vfio_group; +#ifdef CONFIG_SPAPR_TCE_IOMMU + struct { + unsigned long liobn; + kvm_vfio_release_group_callback cb; + } spapr_tce; +#endif }; struct kvm_vfio { @@ -59,6 +65,51 @@ static void kvm_vfio_group_put_external_user(struct vfio_group *vfio_group) symbol_put(vfio_group_put_external_user); } +#ifdef CONFIG_SPAPR_TCE_IOMMU +struct iommu_group *kvm_vfio_find_group_by_liobn(struct kvm *kvm, + unsigned long liobn, kvm_vfio_release_group_callback cb) +{ + struct kvm_vfio_group *kvg; + int group_id; + struct iommu_group *grp; + struct kvm_vfio *kv = NULL; + struct kvm_device *tmp; + + if (!cb) + return NULL; + + /* Find a VFIO KVM device */ + list_for_each_entry(tmp, &kvm->devices, vm_node) { + if (tmp->ops != &kvm_vfio_ops) + continue; + + kv = tmp->private; + break; + } + + if (!kv) + return NULL; + + /* Find a group */ + list_for_each_entry(kvg, &kv->group_list, node) { + if (kvg->spapr_tce.liobn != liobn) + continue; + + if (kvg->spapr_tce.cb) + return NULL; + + kvg->spapr_tce.cb = cb; + group_id = vfio_external_user_iommu_id(kvg->vfio_group); + grp = iommu_group_get_by_id(group_id); + + return grp; + } + + return NULL; +} +EXPORT_SYMBOL_GPL(kvm_vfio_find_group_by_liobn); +#endif + /* * Groups can use the same or different IOMMU domains. If the same then * adding a new group may change the coherency of groups we've previously @@ -170,6 +221,11 @@ static int kvm_vfio_set_group(struct kvm_device *dev, long attr, u64 arg) continue; list_del(&kvg->node); +#ifdef CONFIG_SPAPR_TCE_IOMMU + if (kvg->spapr_tce.cb) + kvg->spapr_tce.cb(dev->kvm, + kvg->spapr_tce.liobn); +#endif kvm_vfio_group_put_external_user(kvg->vfio_group); kfree(kvg); ret = 0; @@ -183,6 +239,62 @@ static int kvm_vfio_set_group(struct kvm_device *dev, long attr, u64 arg) kvm_vfio_update_coherency(dev); return ret; + +#ifdef CONFIG_SPAPR_TCE_IOMMU + case KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE_LIOBN: { + struct kvm_vfio_spapr_tce_liobn param; + unsigned long minsz; + struct kvm_vfio *kv = dev->private; + struct vfio_group *vfio_group; + struct kvm_vfio_group *kvg; + struct fd f; + + minsz = offsetofend(struct kvm_vfio_spapr_tce_liobn, liobn); + + if (copy_from_user(¶m, (void __user *)arg, minsz)) + return -EFAULT; + + if (param.argsz < minsz) + return -EINVAL; + + if (copy_from_user(¶m, (void __user *)arg, minsz)) + return -EFAULT; + + f = fdget(param.fd); + if (!f.file) + return -EBADF; + + vfio_group = kvm_vfio_group_get_external_user(f.file); + fdput(f); + + if (IS_ERR(vfio_group)) + return PTR_ERR(vfio_group); + + ret = -ENOENT; + + mutex_lock(&kv->lock); + + list_for_each_entry(kvg, &kv->group_list, node) { + if (kvg->vfio_group != vfio_group) + continue; + + if (kvg->spapr_tce.liobn) { + ret = -EBUSY; + break; + } + + kvg->spapr_tce.liobn = param.liobn; + ret = 0; + break; + } + + mutex_unlock(&kv->lock); + + kvm_vfio_group_put_external_user(vfio_group); + + return ret; + } +#endif /* CONFIG_SPAPR_TCE_IOMMU */ } return -ENXIO; @@ -207,9 +319,11 @@ static int kvm_vfio_has_attr(struct kvm_device *dev, switch (attr->attr) { case KVM_DEV_VFIO_GROUP_ADD: case KVM_DEV_VFIO_GROUP_DEL: +#ifdef CONFIG_SPAPR_TCE_IOMMU + case KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE_LIOBN: +#endif return 0; } - break; }
In addition to the external VFIO user API, a VFIO KVM device has been introduced recently. sPAPR TCE IOMMU is para-virtualized and the guest does map/unmap via hypercalls which take a logical bus id (LIOBN) as a target IOMMU identifier. LIOBNs are made up and linked to IOMMU groups by the user space. In order to accelerate IOMMU operations in the KVM, we need to tell KVM the information about LIOBN-to-group mapping. For that, a new KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE_LIOBN parameter is added. It accepts a pair of a VFIO group fd and LIOBN. This also adds a new kvm_vfio_find_group_by_liobn() function which receives kvm struct, LIOBN and a callback. As it increases the IOMMU group use counter, the KVMr is required to pass a callback which called when the VFIO group is about to be removed VFIO-KVM tracking so the KVM is able to call iommu_group_put() to release the IOMMU group. The KVM uses kvm_vfio_find_group_by_liobn() once per KVM run and caches the result in kvm_arch. iommu_group_put() for all groups will be called when KVM finishes (in the SPAPR TCE in KVM enablement patch). Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> --- Changes: v3: * total rework * added a release callback into kvm_vfio_find_group_by_liobn so now the user of the API can get a notification if the group is about to disappear --- Documentation/virtual/kvm/devices/vfio.txt | 19 ++++- arch/powerpc/kvm/Kconfig | 1 + arch/powerpc/kvm/Makefile | 3 + include/linux/kvm_host.h | 18 +++++ include/uapi/linux/kvm.h | 7 ++ virt/kvm/vfio.c | 116 ++++++++++++++++++++++++++++- 6 files changed, 161 insertions(+), 3 deletions(-)