| Message ID | c43472bd-b294-fb9d-090f-f99e900a0d33@ozlabs.ru |
|---|---|
| State | Superseded |
| Headers | show |
On Tue, Mar 07, 2017 at 10:07:27PM +1100, Alexey Kardashevskiy wrote: > On 06/03/17 16:04, Alexey Kardashevskiy wrote: > > On 06/03/17 15:30, David Gibson wrote: > >> On Fri, Mar 03, 2017 at 06:09:25PM +1100, Alexey Kardashevskiy wrote: > >>> On 03/03/17 16:59, David Gibson wrote: > >>>> On Thu, Mar 02, 2017 at 07:56:44PM +1100, Alexey Kardashevskiy wrote: > >>>>> This allows the host kernel to handle H_PUT_TCE, H_PUT_TCE_INDIRECT > >>>>> and H_STUFF_TCE requests targeted an IOMMU TCE table used for VFIO > >>>>> without passing them to user space which saves time on switching > >>>>> to user space and back. > >>>>> > >>>>> This adds H_PUT_TCE/H_PUT_TCE_INDIRECT/H_STUFF_TCE handlers to KVM. > >>>>> KVM tries to handle a TCE request in the real mode, if failed > >>>>> it passes the request to the virtual mode to complete the operation. > >>>>> If it a virtual mode handler fails, the request is passed to > >>>>> the user space; this is not expected to happen though. > >>>>> > >>>>> To avoid dealing with page use counters (which is tricky in real mode), > >>>>> this only accelerates SPAPR TCE IOMMU v2 clients which are required > >>>>> to pre-register the userspace memory. The very first TCE request will > >>>>> be handled in the VFIO SPAPR TCE driver anyway as the userspace view > >>>>> of the TCE table (iommu_table::it_userspace) is not allocated till > >>>>> the very first mapping happens and we cannot call vmalloc in real mode. > >>>>> > >>>>> If we fail to update a hardware IOMMU table unexpected reason, we just > >>>>> clear it and move on as there is nothing really we can do about it - > >>>>> for example, if we hot plug a VFIO device to a guest, existing TCE tables > >>>>> will be mirrored automatically to the hardware and there is no interface > >>>>> to report to the guest about possible failures. > >>>>> > >>>>> This adds new attribute - KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE - to > >>>>> the VFIO KVM device. It takes a VFIO group fd and SPAPR TCE table fd > >>>>> and associates a physical IOMMU table with the SPAPR TCE table (which > >>>>> is a guest view of the hardware IOMMU table). The iommu_table object > >>>>> is cached and referenced so we do not have to look up for it in real mode. > >>>>> > >>>>> This does not implement the UNSET counterpart as there is no use for it - > >>>>> once the acceleration is enabled, the existing userspace won't > >>>>> disable it unless a VFIO container is destroyed; this adds necessary > >>>>> cleanup to the KVM_DEV_VFIO_GROUP_DEL handler. > >>>>> > >>>>> As this creates a descriptor per IOMMU table-LIOBN couple (called > >>>>> kvmppc_spapr_tce_iommu_table), it is possible to have several > >>>>> descriptors with the same iommu_table (hardware IOMMU table) attached > >>>>> to the same LIOBN; we do not remove duplicates though as > >>>>> iommu_table_ops::exchange not just update a TCE entry (which is > >>>>> shared among IOMMU groups) but also invalidates the TCE cache > >>>>> (one per IOMMU group). > >>>>> > >>>>> This advertises the new KVM_CAP_SPAPR_TCE_VFIO capability to the user > >>>>> space. > >>>>> > >>>>> This finally makes use of vfio_external_user_iommu_id() which was > >>>>> introduced quite some time ago and was considered for removal. > >>>>> > >>>>> Tests show that this patch increases transmission speed from 220MB/s > >>>>> to 750..1020MB/s on 10Gb network (Chelsea CXGB3 10Gb ethernet card). > >>>>> > >>>>> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> > >>>>> --- > >>>>> Changes: > >>>>> v6: > >>>>> * changed handling of errors returned by kvmppc_(rm_)tce_iommu_(un)map() > >>>>> * moved kvmppc_gpa_to_ua() to TCE validation > >>>>> > >>>>> v5: > >>>>> * changed error codes in multiple places > >>>>> * added bunch of WARN_ON() in places which should not really happen > >>>>> * adde a check that an iommu table is not attached already to LIOBN > >>>>> * dropped explicit calls to iommu_tce_clear_param_check/ > >>>>> iommu_tce_put_param_check as kvmppc_tce_validate/kvmppc_ioba_validate > >>>>> call them anyway (since the previous patch) > >>>>> * if we fail to update a hardware IOMMU table for unexpected reason, > >>>>> this just clears the entry > >>>>> > >>>>> v4: > >>>>> * added note to the commit log about allowing multiple updates of > >>>>> the same IOMMU table; > >>>>> * instead of checking for if any memory was preregistered, this > >>>>> returns H_TOO_HARD if a specific page was not; > >>>>> * fixed comments from v3 about error handling in many places; > >>>>> * simplified TCE handlers and merged IOMMU parts inline - for example, > >>>>> there used to be kvmppc_h_put_tce_iommu(), now it is merged into > >>>>> kvmppc_h_put_tce(); this allows to check IOBA boundaries against > >>>>> the first attached table only (makes the code simpler); > >>>>> > >>>>> v3: > >>>>> * simplified not to use VFIO group notifiers > >>>>> * reworked cleanup, should be cleaner/simpler now > >>>>> > >>>>> v2: > >>>>> * reworked to use new VFIO notifiers > >>>>> * now same iommu_table may appear in the list several times, to be fixed later > >>>>> --- > >>>>> Documentation/virtual/kvm/devices/vfio.txt | 22 +- > >>>>> arch/powerpc/include/asm/kvm_host.h | 8 + > >>>>> arch/powerpc/include/asm/kvm_ppc.h | 4 + > >>>>> include/uapi/linux/kvm.h | 8 + > >>>>> arch/powerpc/kvm/book3s_64_vio.c | 321 ++++++++++++++++++++++++++++- > >>>>> arch/powerpc/kvm/book3s_64_vio_hv.c | 165 ++++++++++++++- > >>>>> arch/powerpc/kvm/powerpc.c | 2 + > >>>>> virt/kvm/vfio.c | 60 ++++++ > >>>>> 8 files changed, 585 insertions(+), 5 deletions(-) > >>>>> > >>>>> diff --git a/Documentation/virtual/kvm/devices/vfio.txt b/Documentation/virtual/kvm/devices/vfio.txt > >>>>> index ef51740c67ca..f95d867168ea 100644 > >>>>> --- a/Documentation/virtual/kvm/devices/vfio.txt > >>>>> +++ b/Documentation/virtual/kvm/devices/vfio.txt > >>>>> @@ -16,7 +16,25 @@ 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: attaches a guest visible TCE table > >>>>> + allocated by sPAPR KVM. > >>>>> + kvm_device_attr.addr points to a struct: > >>>>> > >>>>> -For each, kvm_device_attr.addr points to an int32_t file descriptor > >>>>> -for the VFIO group. > >>>>> + struct kvm_vfio_spapr_tce { > >>>>> + __u32 argsz; > >>>>> + __u32 flags; > >>>>> + __s32 groupfd; > >>>>> + __s32 tablefd; > >>>>> + }; > >>>>> + > >>>>> + where > >>>>> + @argsz is the size of kvm_vfio_spapr_tce_liobn; > >>>>> + @flags are not supported now, must be zero; > >>>>> + @groupfd is a file descriptor for a VFIO group; > >>>>> + @tablefd is a file descriptor for a TCE table allocated via > >>>>> + KVM_CREATE_SPAPR_TCE. > >>>>> diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h > >>>>> index 7bba8f415627..857ae2c6aa39 100644 > >>>>> --- a/arch/powerpc/include/asm/kvm_host.h > >>>>> +++ b/arch/powerpc/include/asm/kvm_host.h > >>>>> @@ -191,6 +191,13 @@ struct kvmppc_pginfo { > >>>>> atomic_t refcnt; > >>>>> }; > >>>>> > >>>>> +struct kvmppc_spapr_tce_iommu_table { > >>>>> + struct rcu_head rcu; > >>>>> + struct list_head next; > >>>>> + struct vfio_group *group; > >>>>> + struct iommu_table *tbl; > >>>>> +}; > >>>>> + > >>>>> struct kvmppc_spapr_tce_table { > >>>>> struct list_head list; > >>>>> struct kvm *kvm; > >>>>> @@ -199,6 +206,7 @@ struct kvmppc_spapr_tce_table { > >>>>> u32 page_shift; > >>>>> u64 offset; /* in pages */ > >>>>> u64 size; /* window size in pages */ > >>>>> + struct list_head iommu_tables; > >>>>> struct page *pages[0]; > >>>>> }; > >>>>> > >>>>> diff --git a/arch/powerpc/include/asm/kvm_ppc.h b/arch/powerpc/include/asm/kvm_ppc.h > >>>>> index 72c2a155641f..66de7e73b3d3 100644 > >>>>> --- a/arch/powerpc/include/asm/kvm_ppc.h > >>>>> +++ b/arch/powerpc/include/asm/kvm_ppc.h > >>>>> @@ -164,6 +164,10 @@ extern long kvmppc_prepare_vrma(struct kvm *kvm, > >>>>> extern void kvmppc_map_vrma(struct kvm_vcpu *vcpu, > >>>>> struct kvm_memory_slot *memslot, unsigned long porder); > >>>>> extern int kvmppc_pseries_do_hcall(struct kvm_vcpu *vcpu); > >>>>> +extern long kvm_spapr_tce_attach_iommu_group(struct kvm *kvm, int tablefd, > >>>>> + struct vfio_group *group); > >>>>> +extern void kvm_spapr_tce_release_iommu_group(struct kvm *kvm, > >>>>> + struct vfio_group *group); > >>>>> > >>>>> extern long kvm_vm_ioctl_create_spapr_tce(struct kvm *kvm, > >>>>> struct kvm_create_spapr_tce_64 *args); > >>>>> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h > >>>>> index f5a52ffb6b58..e743cb0d176e 100644 > >>>>> --- a/include/uapi/linux/kvm.h > >>>>> +++ b/include/uapi/linux/kvm.h > >>>>> @@ -1088,6 +1088,7 @@ 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 3 > >>>>> > >>>>> enum kvm_device_type { > >>>>> KVM_DEV_TYPE_FSL_MPIC_20 = 1, > >>>>> @@ -1109,6 +1110,13 @@ enum kvm_device_type { > >>>>> KVM_DEV_TYPE_MAX, > >>>>> }; > >>>>> > >>>>> +struct kvm_vfio_spapr_tce { > >>>>> + __u32 argsz; > >>>>> + __u32 flags; > >>>>> + __s32 groupfd; > >>>>> + __s32 tablefd; > >>>>> +}; > >>>>> + > >>>>> /* > >>>>> * ioctls for VM fds > >>>>> */ > >>>>> diff --git a/arch/powerpc/kvm/book3s_64_vio.c b/arch/powerpc/kvm/book3s_64_vio.c > >>>>> index 57dd036bd998..85927f467811 100644 > >>>>> --- a/arch/powerpc/kvm/book3s_64_vio.c > >>>>> +++ b/arch/powerpc/kvm/book3s_64_vio.c > >>>>> @@ -27,6 +27,10 @@ > >>>>> #include <linux/hugetlb.h> > >>>>> #include <linux/list.h> > >>>>> #include <linux/anon_inodes.h> > >>>>> +#include <linux/iommu.h> > >>>>> +#include <linux/file.h> > >>>>> +#include <linux/vfio.h> > >>>>> +#include <linux/module.h> > >>>>> > >>>>> #include <asm/tlbflush.h> > >>>>> #include <asm/kvm_ppc.h> > >>>>> @@ -39,6 +43,36 @@ > >>>>> #include <asm/udbg.h> > >>>>> #include <asm/iommu.h> > >>>>> #include <asm/tce.h> > >>>>> +#include <asm/mmu_context.h> > >>>>> + > >>>>> +static void kvm_vfio_group_put_external_user(struct vfio_group *vfio_group) > >>>>> +{ > >>>>> + void (*fn)(struct vfio_group *); > >>>>> + > >>>>> + fn = symbol_get(vfio_group_put_external_user); > >>>>> + if (WARN_ON(!fn)) > >>>>> + return; > >>>>> + > >>>>> + fn(vfio_group); > >>>>> + > >>>>> + symbol_put(vfio_group_put_external_user); > >>>>> +} > >>>>> + > >>>>> +static int kvm_vfio_external_user_iommu_id(struct vfio_group *vfio_group) > >>>>> +{ > >>>>> + int (*fn)(struct vfio_group *); > >>>>> + int ret = -1; > >>>>> + > >>>>> + fn = symbol_get(vfio_external_user_iommu_id); > >>>>> + if (!fn) > >>>>> + return ret; > >>>>> + > >>>>> + ret = fn(vfio_group); > >>>>> + > >>>>> + symbol_put(vfio_external_user_iommu_id); > >>>>> + > >>>>> + return ret; > >>>>> +} > >>>>> > >>>>> static unsigned long kvmppc_tce_pages(unsigned long iommu_pages) > >>>>> { > >>>>> @@ -90,6 +124,130 @@ static long kvmppc_account_memlimit(unsigned long stt_pages, bool inc) > >>>>> return ret; > >>>>> } > >>>>> > >>>>> +static void kvm_spapr_tce_iommu_table_free(struct rcu_head *head) > >>>>> +{ > >>>>> + struct kvmppc_spapr_tce_iommu_table *stit = container_of(head, > >>>>> + struct kvmppc_spapr_tce_iommu_table, rcu); > >>>>> + > >>>>> + iommu_table_put(stit->tbl); > >>>>> + kvm_vfio_group_put_external_user(stit->group); > >>>>> + > >>>>> + kfree(stit); > >>>>> +} > >>>>> + > >>>>> +static void kvm_spapr_tce_liobn_release_iommu_group( > >>>>> + struct kvmppc_spapr_tce_table *stt, > >>>>> + struct vfio_group *group) > >>>>> +{ > >>>>> + struct kvmppc_spapr_tce_iommu_table *stit, *tmp; > >>>>> + > >>>>> + list_for_each_entry_safe(stit, tmp, &stt->iommu_tables, next) { > >>>>> + if (group && (stit->group != group)) > >>>>> + continue; > >>>>> + > >>>>> + list_del_rcu(&stit->next); > >>>>> + > >>>>> + call_rcu(&stit->rcu, kvm_spapr_tce_iommu_table_free); > >>>>> + } > >>>>> +} > >>>>> + > >>>>> +extern void kvm_spapr_tce_release_iommu_group(struct kvm *kvm, > >>>>> + struct vfio_group *group) > >>>>> +{ > >>>>> + struct kvmppc_spapr_tce_table *stt; > >>>>> + > >>>>> + list_for_each_entry_rcu(stt, &kvm->arch.spapr_tce_tables, list) > >>>>> + kvm_spapr_tce_liobn_release_iommu_group(stt, group); > >>>>> +} > >>>>> + > >>>>> +extern long kvm_spapr_tce_attach_iommu_group(struct kvm *kvm, int tablefd, > >>>>> + struct vfio_group *group) > >>>>> +{ > >>>>> + struct kvmppc_spapr_tce_table *stt = NULL; > >>>>> + bool found = false; > >>>>> + struct iommu_table *tbl = NULL; > >>>>> + struct iommu_table_group *table_group; > >>>>> + long i, ret = 0; > >>>>> + struct kvmppc_spapr_tce_iommu_table *stit; > >>>>> + struct fd f; > >>>>> + int group_id; > >>>>> + struct iommu_group *grp; > >>>>> + > >>>>> + group_id = kvm_vfio_external_user_iommu_id(group); > >>>>> + grp = iommu_group_get_by_id(group_id); > >>>>> + if (WARN_ON(!grp)) > >>>>> + return -EIO; > >>>>> + > >>>>> + f = fdget(tablefd); > >>>>> + if (!f.file) { > >>>>> + ret = -EBADF; > >>>>> + goto put_exit; > >>>>> + } > >>>>> + > >>>>> + list_for_each_entry_rcu(stt, &kvm->arch.spapr_tce_tables, list) { > >>>>> + if (stt == f.file->private_data) { > >>>>> + found = true; > >>>>> + break; > >>>>> + } > >>>>> + } > >>>>> + > >>>>> + fdput(f); > >>>>> + > >>>>> + if (!found) { > >>>>> + ret = -EINVAL; > >>>>> + goto put_exit; > >>>>> + } > >>>>> + > >>>>> + table_group = iommu_group_get_iommudata(grp); > >>>>> + if (WARN_ON(!table_group)) { > >>>>> + ret = -EFAULT; > >>>>> + goto put_exit; > >>>>> + } > >>>>> + > >>>>> + for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i) { > >>>>> + struct iommu_table *tbltmp = table_group->tables[i]; > >>>>> + > >>>>> + if (!tbltmp) > >>>>> + continue; > >>>>> + > >>>>> + /* > >>>>> + * Make sure hardware table parameters are exactly the same; > >>>>> + * this is used in the TCE handlers where boundary checks > >>>>> + * use only the first attached table. > >>>>> + */ > >>>>> + if ((tbltmp->it_page_shift == stt->page_shift) && > >>>>> + (tbltmp->it_offset == stt->offset) && > >>>>> + (tbltmp->it_size == stt->size)) { > >>>>> + tbl = tbltmp; > >>>>> + break; > >>>>> + } > >>>>> + } > >>>>> + if (!tbl) { > >>>>> + ret = -EINVAL; > >>>>> + goto put_exit; > >>>>> + } > >>>>> + > >>>>> + list_for_each_entry_rcu(stit, &stt->iommu_tables, next) { > >>>>> + if ((stit->tbl == tbl) && (stit->group == group)) { > >>>>> + ret = -EBUSY; > >>>>> + goto put_exit; > >>>>> + } > >>>>> + } > >>>>> + > >>>>> + iommu_table_get(tbl); > >>>>> + > >>>>> + stit = kzalloc(sizeof(*stit), GFP_KERNEL); > >>>>> + stit->tbl = tbl; > >>>>> + stit->group = group; > >>>>> + > >>>>> + list_add_rcu(&stit->next, &stt->iommu_tables); > >>>>> + > >>>>> +put_exit: > >>>>> + iommu_group_put(grp); > >>>>> + > >>>>> + return ret; > >>>>> +} > >>>>> + > >>>>> static void release_spapr_tce_table(struct rcu_head *head) > >>>>> { > >>>>> struct kvmppc_spapr_tce_table *stt = container_of(head, > >>>>> @@ -132,6 +290,8 @@ static int kvm_spapr_tce_release(struct inode *inode, struct file *filp) > >>>>> > >>>>> list_del_rcu(&stt->list); > >>>>> > >>>>> + kvm_spapr_tce_liobn_release_iommu_group(stt, NULL /* release all */); > >>>>> + > >>>>> kvm_put_kvm(stt->kvm); > >>>>> > >>>>> kvmppc_account_memlimit( > >>>>> @@ -182,6 +342,7 @@ long kvm_vm_ioctl_create_spapr_tce(struct kvm *kvm, > >>>>> stt->offset = args->offset; > >>>>> stt->size = size; > >>>>> stt->kvm = kvm; > >>>>> + INIT_LIST_HEAD_RCU(&stt->iommu_tables); > >>>>> > >>>>> for (i = 0; i < npages; i++) { > >>>>> stt->pages[i] = alloc_page(GFP_KERNEL | __GFP_ZERO); > >>>>> @@ -210,11 +371,99 @@ long kvm_vm_ioctl_create_spapr_tce(struct kvm *kvm, > >>>>> return ret; > >>>>> } > >>>>> > >>>>> +static void kvmppc_clear_tce(struct iommu_table *tbl, unsigned long entry) > >>>>> +{ > >>>>> + unsigned long hpa = 0; > >>>>> + enum dma_data_direction dir = DMA_NONE; > >>>>> + > >>>>> + iommu_tce_xchg(tbl, entry, &hpa, &dir); > >>>>> +} > >>>>> + > >>>>> +static long kvmppc_tce_iommu_mapped_dec(struct kvm *kvm, > >>>>> + struct iommu_table *tbl, unsigned long entry) > >>>>> +{ > >>>>> + struct mm_iommu_table_group_mem_t *mem = NULL; > >>>>> + const unsigned long pgsize = 1ULL << tbl->it_page_shift; > >>>>> + unsigned long *pua = IOMMU_TABLE_USERSPACE_ENTRY(tbl, entry); > >>>>> + > >>>>> + if (WARN_ON_ONCE(!pua)) > >>>>> + return H_HARDWARE; > >>>>> + > >>>>> + mem = mm_iommu_lookup(kvm->mm, *pua, pgsize); > >>>>> + if (!mem) > >>>>> + return H_TOO_HARD; > >>>>> + > >>>>> + mm_iommu_mapped_dec(mem); > >>>>> + > >>>>> + *pua = 0; > >>>>> + > >>>>> + return H_SUCCESS; > >>>>> +} > >>>>> + > >>>>> +static long kvmppc_tce_iommu_unmap(struct kvm *kvm, > >>>>> + struct iommu_table *tbl, unsigned long entry) > >>>>> +{ > >>>>> + enum dma_data_direction dir = DMA_NONE; > >>>>> + unsigned long hpa = 0; > >>>>> + long ret; > >>>>> + > >>>>> + if (iommu_tce_xchg(tbl, entry, &hpa, &dir)) > >>>>> + return H_HARDWARE; > >>>>> + > >>>>> + if (dir == DMA_NONE) > >>>>> + return H_SUCCESS; > >>>>> + > >>>>> + ret = kvmppc_tce_iommu_mapped_dec(kvm, tbl, entry); > >>>>> + if (ret != H_SUCCESS) > >>>>> + iommu_tce_xchg(tbl, entry, &hpa, &dir); > >>>>> + > >>>>> + return ret; > >>>>> +} > >>>>> + > >>>>> +long kvmppc_tce_iommu_map(struct kvm *kvm, struct iommu_table *tbl, > >>>>> + unsigned long entry, unsigned long ua, > >>>>> + enum dma_data_direction dir) > >>>>> +{ > >>>>> + long ret; > >>>>> + unsigned long hpa, *pua = IOMMU_TABLE_USERSPACE_ENTRY(tbl, entry); > >>>>> + struct mm_iommu_table_group_mem_t *mem; > >>>>> + > >>>>> + if (!pua) > >>>>> + /* it_userspace allocation might be delayed */ > >>>>> + return H_TOO_HARD; > >>>>> + > >>>>> + mem = mm_iommu_lookup(kvm->mm, ua, 1ULL << tbl->it_page_shift); > >>>>> + if (!mem) > >>>>> + return H_TOO_HARD; > >>>> > >>>> IIUC this is the virtual mode path, not the real mode patch. Under > >>>> what circumstances could qemu succeed that KVM virtual mode couldn't, > >>>> for either of the above failures? > >>> > >>> The (!pua) failure is handled in tce_iommu_build_v2() from > >>> drivers/vfio/vfio_iommu_spapr_tce.c as: > >>> > >>> > >>> if (!tbl->it_userspace) { > >>> ret = tce_iommu_userspace_view_alloc(tbl, container->mm); > >>> if (ret) > >>> return ret; > >>> } > >> > >> Ah.. which is called from the ioctl() path but not the KVM hcall path, > >> ok, I get it. > >> > >>> The (!mem) can succeed if the container is in VFIO_SPAPR_TCE_IOMMU mode > >>> (not VFIO_SPAPR_TCE_v2_IOMMU). Remember that the userspace can call > >>> ioctl(vfio_kvm_device, KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE) without having > >>> memory preregistered so tables will appear in the > >>> kvmppc_spapr_tce_iommu_table list in KVM. > >> > >> Ok. So in short, the userspace->ioctl() path will handle both v1 and > >> v2 versions of the IOMMU interface, whereas the in-kernel > >> implementation (both real and virtual) will only handle v2. Is that > >> right? > > > > > > Correct. I used to have an explicit check for any memory preregistered, now > > it is as bit less obvious but still the case. > > > > > > > > > >> > >>>>> + > >>>>> + if (WARN_ON_ONCE(mm_iommu_ua_to_hpa(mem, ua, &hpa))) > >>>>> + return H_HARDWARE; > >>>>> + > >>>>> + if (mm_iommu_mapped_inc(mem)) > >>>>> + return H_CLOSED; > >>>>> + > >>>>> + ret = iommu_tce_xchg(tbl, entry, &hpa, &dir); > >>>>> + if (ret) { > >>>> > >>>> It thought the xchg could basically never fail, so this should be > >>>> another WARN_ON(). > >>> > >>> > >>> Correct. > >>> > >>> > >>>>> + mm_iommu_mapped_dec(mem); > >>>>> + return H_TOO_HARD; > >>>>> + } > >>>>> + > >>>>> + if (dir != DMA_NONE) > >>>>> + kvmppc_tce_iommu_mapped_dec(kvm, tbl, entry); > >>>>> + > >>>>> + *pua = ua; > >>>>> + > >>>>> + return 0; > >>>>> +} > >>>>> + > >>>>> long kvmppc_h_put_tce(struct kvm_vcpu *vcpu, unsigned long liobn, > >>>>> unsigned long ioba, unsigned long tce) > >>>>> { > >>>>> struct kvmppc_spapr_tce_table *stt; > >>>>> - long ret; > >>>>> + long ret, idx; > >>>>> + struct kvmppc_spapr_tce_iommu_table *stit; > >>>>> + unsigned long entry, ua = 0; > >>>>> + enum dma_data_direction dir; > >>>>> > >>>>> /* udbg_printf("H_PUT_TCE(): liobn=0x%lx ioba=0x%lx, tce=0x%lx\n", */ > >>>>> /* liobn, ioba, tce); */ > >>>>> @@ -231,7 +480,35 @@ long kvmppc_h_put_tce(struct kvm_vcpu *vcpu, unsigned long liobn, > >>>>> if (ret != H_SUCCESS) > >>>>> return ret; > >>>>> > >>>>> - kvmppc_tce_put(stt, ioba >> stt->page_shift, tce); > >>>>> + dir = iommu_tce_direction(tce); > >>>>> + if ((dir != DMA_NONE) && kvmppc_gpa_to_ua(vcpu->kvm, > >>>>> + tce & ~(TCE_PCI_READ | TCE_PCI_WRITE), &ua, NULL)) > >>>>> + return H_PARAMETER; > >>>>> + > >>>>> + entry = ioba >> stt->page_shift; > >>>>> + > >>>>> + list_for_each_entry_lockless(stit, &stt->iommu_tables, next) { > >>>>> + if (dir == DMA_NONE) { > >>>>> + ret = kvmppc_tce_iommu_unmap(vcpu->kvm, > >>>>> + stit->tbl, entry); > >>>>> + } else { > >>>>> + idx = srcu_read_lock(&vcpu->kvm->srcu); > >>>>> + ret = kvmppc_tce_iommu_map(vcpu->kvm, stit->tbl, > >>>>> + entry, ua, dir); > >>>>> + srcu_read_unlock(&vcpu->kvm->srcu, idx); > >>>>> + } > >>>>> + > >>>>> + if (ret == H_SUCCESS) > >>>>> + continue; > >>>>> + > >>>>> + if (ret == H_TOO_HARD) > >>>>> + return ret; > >>>>> + > >>>>> + WARN_ON_ONCE(1); > >>>>> + kvmppc_clear_tce(stit->tbl, entry); > >>>>> + } > >>>>> + > >>>>> + kvmppc_tce_put(stt, entry, tce); > >>>>> > >>>>> return H_SUCCESS; > >>>>> } > >>>>> @@ -246,6 +523,7 @@ long kvmppc_h_put_tce_indirect(struct kvm_vcpu *vcpu, > >>>>> unsigned long entry, ua = 0; > >>>>> u64 __user *tces; > >>>>> u64 tce; > >>>>> + struct kvmppc_spapr_tce_iommu_table *stit; > >>>>> > >>>>> stt = kvmppc_find_table(vcpu->kvm, liobn); > >>>>> if (!stt) > >>>>> @@ -284,6 +562,26 @@ long kvmppc_h_put_tce_indirect(struct kvm_vcpu *vcpu, > >>>>> if (ret != H_SUCCESS) > >>>>> goto unlock_exit; > >>>>> > >>>>> + if (kvmppc_gpa_to_ua(vcpu->kvm, > >>>>> + tce & ~(TCE_PCI_READ | TCE_PCI_WRITE), > >>>>> + &ua, NULL)) > >>>>> + return H_PARAMETER; > >>>>> + > >>>>> + list_for_each_entry_lockless(stit, &stt->iommu_tables, next) { > >>>>> + ret = kvmppc_tce_iommu_map(vcpu->kvm, > >>>>> + stit->tbl, entry + i, ua, > >>>>> + iommu_tce_direction(tce)); > >>>>> + > >>>>> + if (ret == H_SUCCESS) > >>>>> + continue; > >>>>> + > >>>>> + if (ret == H_TOO_HARD) > >>>>> + goto unlock_exit; > >>>>> + > >>>>> + WARN_ON_ONCE(1); > >>>>> + kvmppc_clear_tce(stit->tbl, entry); > >>>>> + } > >>>>> + > >>>>> kvmppc_tce_put(stt, entry + i, tce); > >>>>> } > >>>>> > >>>>> @@ -300,6 +598,7 @@ long kvmppc_h_stuff_tce(struct kvm_vcpu *vcpu, > >>>>> { > >>>>> struct kvmppc_spapr_tce_table *stt; > >>>>> long i, ret; > >>>>> + struct kvmppc_spapr_tce_iommu_table *stit; > >>>>> > >>>>> stt = kvmppc_find_table(vcpu->kvm, liobn); > >>>>> if (!stt) > >>>>> @@ -313,6 +612,24 @@ long kvmppc_h_stuff_tce(struct kvm_vcpu *vcpu, > >>>>> if (tce_value & (TCE_PCI_WRITE | TCE_PCI_READ)) > >>>>> return H_PARAMETER; > >>>>> > >>>>> + list_for_each_entry_lockless(stit, &stt->iommu_tables, next) { > >>>>> + unsigned long entry = ioba >> stit->tbl->it_page_shift; > >>>>> + > >>>>> + for (i = 0; i < npages; ++i) { > >>>>> + ret = kvmppc_tce_iommu_unmap(vcpu->kvm, > >>>>> + stit->tbl, entry + i); > >>>>> + > >>>>> + if (ret == H_SUCCESS) > >>>>> + continue; > >>>>> + > >>>>> + if (ret == H_TOO_HARD) > >>>>> + return ret; > >>>>> + > >>>>> + WARN_ON_ONCE(1); > >>>>> + kvmppc_clear_tce(stit->tbl, entry); > >>>>> + } > >>>>> + } > >>>>> + > >>>>> for (i = 0; i < npages; ++i, ioba += (1ULL << stt->page_shift)) > >>>>> kvmppc_tce_put(stt, ioba >> stt->page_shift, tce_value); > >>>>> > >>>>> diff --git a/arch/powerpc/kvm/book3s_64_vio_hv.c b/arch/powerpc/kvm/book3s_64_vio_hv.c > >>>>> index 440d3ab5dc32..3ad06badc552 100644 > >>>>> --- a/arch/powerpc/kvm/book3s_64_vio_hv.c > >>>>> +++ b/arch/powerpc/kvm/book3s_64_vio_hv.c > >>>>> @@ -161,11 +161,108 @@ long kvmppc_gpa_to_ua(struct kvm *kvm, unsigned long gpa, > >>>>> EXPORT_SYMBOL_GPL(kvmppc_gpa_to_ua); > >>>>> > >>>>> #ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE > >>>>> +static void kvmppc_rm_clear_tce(struct iommu_table *tbl, unsigned long entry) > >>>>> +{ > >>>>> + unsigned long hpa = 0; > >>>>> + enum dma_data_direction dir = DMA_NONE; > >>>>> + > >>>>> + iommu_tce_xchg_rm(tbl, entry, &hpa, &dir); > >>>>> +} > >>>>> + > >>>>> +static long kvmppc_rm_tce_iommu_mapped_dec(struct kvm *kvm, > >>>>> + struct iommu_table *tbl, unsigned long entry) > >>>>> +{ > >>>>> + struct mm_iommu_table_group_mem_t *mem = NULL; > >>>>> + const unsigned long pgsize = 1ULL << tbl->it_page_shift; > >>>>> + unsigned long *pua = IOMMU_TABLE_USERSPACE_ENTRY(tbl, entry); > >>>>> + > >>>>> + if (WARN_ON_ONCE(!pua)) > >>>>> + return H_HARDWARE; > >>>> > >>>> So.. I know I encouraged WARN_ON()s, but is it safe to call WARN_ON() > >>>> from real mode? > >>> > >>> Ouch. Tried WARN_ON_ONCE(1) in kvmppc_rm_h_stuff_tce() and got "rcu_sched > >>> detected stalls" straight away. > >> > >> Bother. Sorry I didn't think of that earlier. > >> > >>> What do I replace it with, in documenting purposes? > >>> > >>> - if (WARN_ON_ONCE(!pua)) > >>> + if (!pua) /* Not expected to fail */ > >> > >> So, I'd suggest adding a WARN_ON_RM() or whatever macro to wrap this > >> at least. As you may have seen I discussed this with mpe on IRC and > >> printk() should work, so you could just put a printk() and > >> dump_stack() in there. > > > > Yes, noticed. Thanks! > > > > Something like this? Copied from include/asm-generic/bug.h. Assuming you've checked that pr_err(), dump_stack() and the section reference work ok in real mode, that looks fine. > > > diff --git a/arch/powerpc/kvm/book3s_64_vio_hv.c > b/arch/powerpc/kvm/book3s_64_vio_hv.c > index 3ad06badc552..9d6f7e2043ca 100644 > --- a/arch/powerpc/kvm/book3s_64_vio_hv.c > +++ b/arch/powerpc/kvm/book3s_64_vio_hv.c > @@ -40,6 +40,31 @@ > #include <asm/iommu.h> > #include <asm/tce.h> > > +#ifdef CONFIG_BUG > + > +#define WARN_ON_ONCE_RM(condition) ({ \ > + static bool __section(.data.unlikely) __warned; \ > + int __ret_warn_once = !!(condition); \ > + \ > + if (unlikely(__ret_warn_once && !__warned)) { \ > + __warned = true; \ > + pr_err("WARN_ON_ONCE_RM: (%s) at %s:%u\n", \ > + __stringify(condition), \ > + __func__, __LINE__); \ > + dump_stack(); \ > + } \ > + unlikely(__ret_warn_once); \ > +}) > + > +#else > + > +#define WARN_ON_ONCE_RM(condition) ({ \ > + int __ret_warn_on = !!(condition); \ > + unlikely(__ret_warn_on); \ > +}) > + > +#endif > + > > > > > > > > > > >
diff --git a/arch/powerpc/kvm/book3s_64_vio_hv.c b/arch/powerpc/kvm/book3s_64_vio_hv.c index 3ad06badc552..9d6f7e2043ca 100644 --- a/arch/powerpc/kvm/book3s_64_vio_hv.c +++ b/arch/powerpc/kvm/book3s_64_vio_hv.c @@ -40,6 +40,31 @@ #include <asm/iommu.h> #include <asm/tce.h> +#ifdef CONFIG_BUG + +#define WARN_ON_ONCE_RM(condition) ({ \ + static bool __section(.data.unlikely) __warned; \ + int __ret_warn_once = !!(condition); \ + \ + if (unlikely(__ret_warn_once && !__warned)) { \ + __warned = true; \ + pr_err("WARN_ON_ONCE_RM: (%s) at %s:%u\n", \ + __stringify(condition), \ + __func__, __LINE__); \ + dump_stack(); \ + } \ + unlikely(__ret_warn_once); \ +}) + +#else + +#define WARN_ON_ONCE_RM(condition) ({ \ + int __ret_warn_on = !!(condition); \ + unlikely(__ret_warn_on); \ +}) + +#endif +