On 24/02/17 13:14, David Gibson wrote:
> On Wed, Feb 22, 2017 at 07:21:33PM +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 <a...@ozlabs.ru>
>
> I have some comments on this patch, but all the definite ones are
> pretty minor and could be done as later cleanups.
>
> I have some more serious queries, but they are just queries and
> requests for clarification. If there are satisfactory answers to
> them, I'll add my R-b.
>
>
> ---
>> Changes:
>> 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 | 307
>> ++++++++++++++++++++++++++++-
>> arch/powerpc/kvm/book3s_64_vio_hv.c | 152 +++++++++++++-
>> arch/powerpc/kvm/powerpc.c | 2 +
>> virt/kvm/vfio.c | 60 ++++++
>> 8 files changed, 555 insertions(+), 8 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 e59b172666cd..a827006941f8 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 e04b7fb8ccaa..b8a39dec92cf 100644
>> --- a/arch/powerpc/include/asm/kvm_ppc.h
>> +++ b/arch/powerpc/include/asm/kvm_ppc.h
>> @@ -163,6 +163,10 @@ 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 a2c9bb5a0ead..cdfa01169bd2 100644
>> --- a/include/uapi/linux/kvm.h
>> +++ b/include/uapi/linux/kvm.h
>> @@ -1076,6 +1076,7 @@ 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,
>> @@ -1097,6 +1098,13 @@ 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 15df8ae627d9..062407af09ee 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;
>
> I think it would be nicer to have a function that goes directly from
> vfio_group to iommu_group rather than going via id. That can be a
> later cleanup, though.
>
>> +
>> + 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(
>> @@ -181,6 +341,7 @@ 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);
>> @@ -209,11 +370,102 @@ 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;
>
> Initialization is unnecessary for the variable above.
>
>> + const unsigned long pgsize = 1ULL << tbl->it_page_shift;
>> + unsigned long *pua = IOMMU_TABLE_USERSPACE_ENTRY(tbl, entry);
>> +
>> + if (WARN_ON(!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 gpa,
>> + enum dma_data_direction dir)
>> +{
>> + long ret;
>> + unsigned long hpa, ua, *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;
>> +
>> + if (kvmppc_gpa_to_ua(kvm, gpa, &ua, NULL))
>> + return H_PARAMETER;
>> +
>> + mem = mm_iommu_lookup(kvm->mm, ua, 1ULL << tbl->it_page_shift);
>> + if (!mem)
>> + return H_TOO_HARD;
>> +
>> + if (WARN_ON(mm_iommu_ua_to_hpa(mem, ua, &hpa)))
>> + return H_HARDWARE;
>
> Remind me - could a failure here be triggered by userspace failing to
> preregister all the memory it should?
mm_iommu_lookup() should fail first as the only reason for
mm_iommu_ua_to_hpa() to fail is (entry >= mem->entries) but this is checked
in mm_iommu_lookup().
>
>> + if (mm_iommu_mapped_inc(mem))
>> + return H_CLOSED;
>> +
>> + ret = iommu_tce_xchg(tbl, entry, &hpa, &dir);
>> + if (ret) {
>> + 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, gpa;
>> + enum dma_data_direction dir;
>>
>> /* udbg_printf("H_PUT_TCE(): liobn=0x%lx ioba=0x%lx, tce=0x%lx\n", */
>> /* liobn, ioba, tce); */
>> @@ -230,7 +482,28 @@ 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);
>> + entry = ioba >> stt->page_shift;
>> + gpa = tce & ~(TCE_PCI_READ | TCE_PCI_WRITE);
>> + dir = iommu_tce_direction(tce);
>> +
>> + 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, gpa, dir);
>> + srcu_read_unlock(&vcpu->kvm->srcu, idx);
>> + }
>> +
>> + if (WARN_ON_ONCE(ret == H_HARDWARE))
>> + kvmppc_clear_tce(stit->tbl, entry);
>> + else if (ret != H_SUCCESS)
>> + return ret;
>> + }
>> +
>> + kvmppc_tce_put(stt, entry, tce);
>>
>> return H_SUCCESS;
>> }
>> @@ -242,9 +515,10 @@ long kvmppc_h_put_tce_indirect(struct kvm_vcpu *vcpu,
>> {
>> struct kvmppc_spapr_tce_table *stt;
>> long i, ret = H_SUCCESS, idx;
>> - unsigned long entry, ua = 0;
>> + unsigned long entry, ua = 0, gpa;
>> u64 __user *tces;
>> u64 tce;
>> + struct kvmppc_spapr_tce_iommu_table *stit;
>>
>> stt = kvmppc_find_table(vcpu->kvm, liobn);
>> if (!stt)
>> @@ -283,6 +557,18 @@ long kvmppc_h_put_tce_indirect(struct kvm_vcpu *vcpu,
>> if (ret != H_SUCCESS)
>> goto unlock_exit;
>>
>> + gpa = tce & ~(TCE_PCI_READ | TCE_PCI_WRITE);
>> +
>> + list_for_each_entry_lockless(stit, &stt->iommu_tables, next) {
>> + ret = kvmppc_tce_iommu_map(vcpu->kvm,
>> + stit->tbl, entry + i, gpa,
>> + iommu_tce_direction(tce));
>> + if (WARN_ON_ONCE(ret == H_HARDWARE))
>> + kvmppc_clear_tce(stit->tbl, entry);
>> + else if (ret != H_SUCCESS)
>> + goto unlock_exit;
>> + }
>> +
>> kvmppc_tce_put(stt, entry + i, tce);
>> }
>>
>> @@ -299,6 +585,7 @@ 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)
>> @@ -312,6 +599,20 @@ 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 (WARN_ON_ONCE(ret == H_HARDWARE))
>> + kvmppc_clear_tce(stit->tbl, entry);
>> + else if (ret != H_SUCCESS)
>> + return ret;
>> + }
>> + }
>> +
>> 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 92d769f4eaea..4a1d978ebd98 100644
>> --- a/arch/powerpc/kvm/book3s_64_vio_hv.c
>> +++ b/arch/powerpc/kvm/book3s_64_vio_hv.c
>> @@ -161,11 +161,111 @@ 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(!pua))
>> + return H_HARDWARE;
>> +
>> + pua = (void *) vmalloc_to_phys(pua);
>> + if (!pua)
>> + return H_TOO_HARD;
>> +
>> + mem = mm_iommu_lookup_rm(kvm->mm, *pua, pgsize);
>> + if (!mem)
>> + return H_TOO_HARD;
>> +
>> + mm_iommu_mapped_dec(mem);
>> +
>> + *pua = 0;
>> +
>> + return H_SUCCESS;
>> +}
>> +
>> +static long kvmppc_rm_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_rm(tbl, entry, &hpa, &dir))
>> + return H_HARDWARE;
>
> To avoid a double WARN() (and to make the warnings easier to
> understand) I'd suggest putting a WARN_ON() here, rather than in the
> callers when they receieve an H_HARDWARE. IIUC this really shouldn't
> ever happen, and it certainly can't be the guest's fault?
Makes sense.
>> +
>> + if (dir == DMA_NONE)
>> + return H_SUCCESS;
>> +
>> + ret = kvmppc_rm_tce_iommu_mapped_dec(kvm, tbl, entry);
>> + if (ret)
>> + iommu_tce_xchg_rm(tbl, entry, &hpa, &dir);
>> +
>> + return ret;
>> +}
>> +
>> +static long kvmppc_rm_tce_iommu_map(struct kvm *kvm, struct iommu_table
>> *tbl,
>> + unsigned long entry, unsigned long gpa,
>> + enum dma_data_direction dir)
>> +{
>> + long ret;
>> + unsigned long hpa = 0, ua;
>> + unsigned long *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;
>> +
>> + if (kvmppc_gpa_to_ua(kvm, gpa, &ua, NULL))
>> + return H_PARAMETER;
Referred below as [1]
>> +
>> + mem = mm_iommu_lookup_rm(kvm->mm, ua, 1ULL << tbl->it_page_shift);
>> + if (!mem)
>> + return H_TOO_HARD;
>> +
>> + if (WARN_ON(mm_iommu_ua_to_hpa_rm(mem, ua, &hpa)))
>> + return H_HARDWARE;
>> +
>> + pua = (void *) vmalloc_to_phys(pua);
>> + if (WARN_ON(!pua))
>> + return H_HARDWARE;
>> +
>> + if (WARN_ON(mm_iommu_mapped_inc(mem)))
>> + return H_CLOSED;
>> +
>> + ret = iommu_tce_xchg_rm(tbl, entry, &hpa, &dir);
>> + if (ret) {
>> + mm_iommu_mapped_dec(mem);
>> + return H_TOO_HARD;
>> + }
>> +
>> + if (dir != DMA_NONE)
>> + kvmppc_rm_tce_iommu_mapped_dec(kvm, tbl, entry);
>> +
>> + *pua = ua;
>> +
>> + return 0;
>> +}
>> +
>> long kvmppc_rm_h_put_tce(struct kvm_vcpu *vcpu, unsigned long liobn,
>> unsigned long ioba, unsigned long tce)
>> {
>> struct kvmppc_spapr_tce_table *stt;
>> long ret;
>> + struct kvmppc_spapr_tce_iommu_table *stit;
>> + unsigned long entry, gpa;
>> + enum dma_data_direction dir;
>>
>> /* udbg_printf("H_PUT_TCE(): liobn=0x%lx ioba=0x%lx, tce=0x%lx\n", */
>> /* liobn, ioba, tce); */
>> @@ -182,7 +282,25 @@ long kvmppc_rm_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);
>> + entry = ioba >> stt->page_shift;
>> + gpa = tce & ~(TCE_PCI_READ | TCE_PCI_WRITE);
>> + dir = iommu_tce_direction(tce);
>> +
>> + list_for_each_entry_lockless(stit, &stt->iommu_tables, next) {
>> + if (dir == DMA_NONE)
>> + ret = kvmppc_rm_tce_iommu_unmap(vcpu->kvm,
>> + stit->tbl, entry);
>> + else
>> + ret = kvmppc_rm_tce_iommu_map(vcpu->kvm,
>> + stit->tbl, entry, gpa, dir);
>> +
>> + if (WARN_ON_ONCE(ret == H_HARDWARE))
>> + kvmppc_rm_clear_tce(stit->tbl, entry);
>> + else if (ret != H_SUCCESS)
>> + return ret;
>> + }
>> +
>> + kvmppc_tce_put(stt, entry, tce);
>>
>> return H_SUCCESS;
>> }
>> @@ -220,9 +338,10 @@ long kvmppc_rm_h_put_tce_indirect(struct kvm_vcpu *vcpu,
>> {
>> struct kvmppc_spapr_tce_table *stt;
>> long i, ret = H_SUCCESS;
>> - unsigned long tces, entry, ua = 0;
>> + unsigned long tces, entry, ua = 0, tce, gpa;
>> unsigned long *rmap = NULL;
>> bool prereg = false;
>> + struct kvmppc_spapr_tce_iommu_table *stit;
>>
>> stt = kvmppc_find_table(vcpu->kvm, liobn);
>> if (!stt)
>> @@ -287,12 +406,24 @@ long kvmppc_rm_h_put_tce_indirect(struct kvm_vcpu
>> *vcpu,
>> }
>>
>> for (i = 0; i < npages; ++i) {
>> - unsigned long tce = be64_to_cpu(((u64 *)tces)[i]);
>> + tce = be64_to_cpu(((u64 *)tces)[i]);
>>
>> ret = kvmppc_tce_validate(stt, tce);
>> if (ret != H_SUCCESS)
>> goto unlock_exit;
>>
>> + gpa = tce & ~(TCE_PCI_READ | TCE_PCI_WRITE);
>> +
>> + list_for_each_entry_lockless(stit, &stt->iommu_tables, next) {
>> + ret = kvmppc_rm_tce_iommu_map(vcpu->kvm,
>> + stit->tbl, entry + i, gpa,
>> + iommu_tce_direction(tce));
>> + if (WARN_ON_ONCE(ret == H_HARDWARE))
>
> I don't think you need the WARN() here - the only H_HARDWARE failure
> path in iommu_map() already includes a WARN().
True, I can drop it here.
>
>> + kvmppc_rm_clear_tce(stit->tbl, entry);
>> + else if (ret != H_SUCCESS)
>> + goto unlock_exit;
>
> It's also not clear to me why the H_HARDWARE error path clears the
> entry, but the other failure paths don't. Or why an H_HARDWARE will
> result in continuing to set the rest of the TCEs, but other failures
> won't.
The idea was that other failures still have some chance that handling may
succeed in virtual mode or via QEMU, H_HARDWARE is fatal.
I am just not sure if H_PARAMETER is what I want to return at [1], to make
the calling code simplier, I could return H_HARDWARE there as well (instead
of H_PARAMETER).
>
>> + }
>> +
>> kvmppc_tce_put(stt, entry + i, tce);
>> }
>>
>> @@ -309,6 +440,7 @@ long kvmppc_rm_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)
>> @@ -322,6 +454,20 @@ long kvmppc_rm_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_rm_tce_iommu_unmap(vcpu->kvm,
>> + stit->tbl, entry + i);
>> +
>> + if (WARN_ON_ONCE(ret == H_HARDWARE))
>> + kvmppc_rm_clear_tce(stit->tbl, entry);
>
> As noted earlier, I think this WARN belongs within iommu_unmap()
> rather than out here.
>
>> + else if (ret != H_SUCCESS)
>> + return ret;
>> + }
>> + }
>> +
>> 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/powerpc.c b/arch/powerpc/kvm/powerpc.c
>> index cd892dec7cb6..f3127dc87912 100644
>> --- a/arch/powerpc/kvm/powerpc.c
>> +++ b/arch/powerpc/kvm/powerpc.c
>> @@ -536,6 +536,8 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long
>> ext)
>> #ifdef CONFIG_PPC_BOOK3S_64
>> case KVM_CAP_SPAPR_TCE:
>> case KVM_CAP_SPAPR_TCE_64:
>> + /* fallthrough */
>> + case KVM_CAP_SPAPR_TCE_VFIO:
>> case KVM_CAP_PPC_RTAS:
>> case KVM_CAP_PPC_FIXUP_HCALL:
>> case KVM_CAP_PPC_ENABLE_HCALL:
>> diff --git a/virt/kvm/vfio.c b/virt/kvm/vfio.c
>> index d32f239eb471..2b7dc22265fe 100644
>> --- a/virt/kvm/vfio.c
>> +++ b/virt/kvm/vfio.c
>> @@ -20,6 +20,10 @@
>> #include <linux/vfio.h>
>> #include "vfio.h"
>>
>> +#ifdef CONFIG_SPAPR_TCE_IOMMU
>> +#include <asm/kvm_ppc.h>
>> +#endif
>> +
>> struct kvm_vfio_group {
>> struct list_head node;
>> struct vfio_group *vfio_group;
>> @@ -211,6 +215,9 @@ static int kvm_vfio_set_group(struct kvm_device *dev,
>> long attr, u64 arg)
>>
>> mutex_unlock(&kv->lock);
>>
>> +#ifdef CONFIG_SPAPR_TCE_IOMMU
>> + kvm_spapr_tce_release_iommu_group(dev->kvm, vfio_group);
>> +#endif
>> kvm_vfio_group_set_kvm(vfio_group, NULL);
>>
>> kvm_vfio_group_put_external_user(vfio_group);
>> @@ -218,6 +225,53 @@ 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: {
>> + struct kvm_vfio_spapr_tce 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, tablefd);
>> +
>> + if (copy_from_user(¶m, (void __user *)arg, minsz))
>> + return -EFAULT;
>> +
>> + if (param.argsz < minsz || param.flags)
>> + return -EINVAL;
>> +
>> + f = fdget(param.groupfd);
>> + 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;
>> +
>> + ret = kvm_spapr_tce_attach_iommu_group(dev->kvm,
>> + param.tablefd, vfio_group);
>> +
>> + break;
>> + }
>> +
>> + mutex_unlock(&kv->lock);
>> +
>> + return ret;
>> + }
>> +#endif /* CONFIG_SPAPR_TCE_IOMMU */
>> }
>>
>> return -ENXIO;
>> @@ -242,6 +296,9 @@ 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:
>> +#endif
>> return 0;
>> }
>>
>> @@ -257,6 +314,9 @@ static void kvm_vfio_destroy(struct kvm_device *dev)
>> struct kvm_vfio_group *kvg, *tmp;
>>
>> list_for_each_entry_safe(kvg, tmp, &kv->group_list, node) {
>> +#ifdef CONFIG_SPAPR_TCE_IOMMU
>> + kvm_spapr_tce_release_iommu_group(dev->kvm, kvg->vfio_group);
>> +#endif
>> kvm_vfio_group_set_kvm(kvg->vfio_group, NULL);
>> kvm_vfio_group_put_external_user(kvg->vfio_group);
>> list_del(&kvg->node);
>
--
Alexey
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