Re: [PATCH kernel v4 10/10] KVM: PPC: VFIO: Add in-kernel acceleration for VFIO

David Gibson
2017-02-09T06:41:12Z

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On Tue, Feb 07, 2017 at 06:17:11PM +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.
>
> 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:
> 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
> ---
>
> This has separate copies of handlers for real and virtual modes as
> in fact H_PUT_TCE and H_STUFF_TCE could share a lot (common helpers
> would take a "realmode" flag) but H_PUT_TCE_INDIRECT uses get_user()
> in virtual mode and direct access in real mode and having a common
> helper for it would make things uglier imho.
>
>
> ---
> 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 | 319 ++++++++++++++++++++++++++++-
> arch/powerpc/kvm/book3s_64_vio_hv.c | 172 +++++++++++++++-
> arch/powerpc/kvm/powerpc.c | 2 +
> virt/kvm/vfio.c | 60 ++++++
> 8 files changed, 590 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 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 37bc9e7e90ba..da1410bd6b36 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 9a7b7fca5e84..cb0469151e35 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 +124,123 @@ 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 (!grp)
> + return -EFAULT;

EFAULT doesn't look right, that's usually means userspace has give us
a bad address. What does failure to look up the iommu group by id
mean here?

> +
> + 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 = -ENODEV;

ENODEV doesn't look right either. That generally means you're trying
to use a device or facility that doesn't exist. This case just means
you've passed a file handle that either isn't a TCE table at all, or
os one associated with a different VM. -EINVAL, I guess, overloaded
as it is.

> + goto put_exit;

Don't you need to put the table fd as well as the iommu group which
you put in that exit path?

> + }
> +
> + table_group = iommu_group_get_iommudata(grp);
> + if (WARN_ON(!table_group)) {
> + ret = -EFAULT;
> + goto put_exit;

Again don't you need to put the table fd as well.

> + }
> +
> + 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 = -ENODEV;

Again, ENODEV doesn't seem right. Here the problem is that the host
hardware constraints don't match the guest hardware constraints.
Hmm. EIO? ENOSPC?

> + 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);

So if you add the same group to the same liobn multiple times, you'll
get multiple identical entries in this list.

I guess that's mostly harmless... although.. does it allow the user to
force the allocation of arbitrary amounts of kernel memory in that
list?

> +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 +283,8 @@ 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 +334,7 @@ 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 +363,94 @@ long kvm_vm_ioctl_create_spapr_tce(struct kvm *kvm,
> return ret;
> }
>
> +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 (!pua)
> + return H_HARDWARE;

What could trigger this error? Should it be a WARN_ON?

> + 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 (mm_iommu_ua_to_hpa(mem, ua, &hpa))
> + return H_HARDWARE;

IIUC this would happen if qemu had failed to preregister all of guest
RAM, making this indeed an H_HARDWARE.

> + if (mm_iommu_mapped_inc(mem))
> + return H_HARDWARE;

I'm less clear on when this one would happen.

> +
> + 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); */
> @@ -230,6 +467,36 @@ long kvmppc_h_put_tce(struct kvm_vcpu *vcpu, unsigned long liobn,
> if (ret != H_SUCCESS)
> return ret;
>
> + stit = list_first_entry_or_null(&stt->iommu_tables,
> + struct kvmppc_spapr_tce_iommu_table, next);
> + if (stit) {
> + entry = ioba >> stit->tbl->it_page_shift;
> + gpa = tce & ~(TCE_PCI_READ | TCE_PCI_WRITE);
> + dir = iommu_tce_direction(tce);
> +
> + if (dir == DMA_NONE) {
> + if (iommu_tce_clear_param_check(stit->tbl, ioba, 0, 1))
> + return H_PARAMETER;
> + } else {
> + if (iommu_tce_put_param_check(stit->tbl, ioba, gpa))

Any way you could make these param check functions based on stt
instead of stit->tbl? That would let you do them before checking if
there are any hw tables to update, avaoiding the somewhat awkward
if (at least one)
for (each one)
construct.

> + return H_PARAMETER;
> + }
> +
> + 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 (ret != H_SUCCESS)
> + return ret;

Doesn't this error path need to clean up for the case where you
managed to update some backing TCE tables, but then failed later ones?

> + }
> + }
> +
> kvmppc_tce_put(stt, ioba >> stt->page_shift, tce);
>
> return H_SUCCESS;
> @@ -242,9 +509,10 @@ 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, gpa, ua = 0;
> u64 __user *tces;
> u64 tce;
> + struct kvmppc_spapr_tce_iommu_table *stit;
>
> stt = kvmppc_find_table(vcpu->kvm, liobn);
> if (!stt)
> @@ -272,6 +540,9 @@ long kvmppc_h_put_tce_indirect(struct kvm_vcpu *vcpu,
> }
> tces = (u64 __user *) ua;
>
> + stit = list_first_entry_or_null(&stt->iommu_tables,
> + struct kvmppc_spapr_tce_iommu_table, next);
> +
> for (i = 0; i < npages; ++i) {
> if (get_user(tce, tces + i)) {
> ret = H_TOO_HARD;
> @@ -282,6 +553,15 @@ long kvmppc_h_put_tce_indirect(struct kvm_vcpu *vcpu,
> ret = kvmppc_tce_validate(stt, tce);
> if (ret != H_SUCCESS)
> goto unlock_exit;
> +
> + if (stit) {
> + gpa = tce & ~(TCE_PCI_READ | TCE_PCI_WRITE);
> + ret = iommu_tce_put_param_check(stit->tbl,
> + ioba + (i << stit->tbl->it_page_shift),
> + gpa);
> + if (ret != H_SUCCESS)
> + goto unlock_exit;
> + }
> }
>
> for (i = 0; i < npages; ++i) {
> @@ -291,6 +571,21 @@ long kvmppc_h_put_tce_indirect(struct kvm_vcpu *vcpu,
> }
> tce = be64_to_cpu(tce);
>
> + if (stit) {
> + for (i = 0; i < npages; ++i) {
> + 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 (ret != H_SUCCESS)
> + goto unlock_exit;
> + }

Um.. what value will this for_each leave in stit after completion? I
suspect it will be something bogus, which means re-using stit in the
next 0..npages loop iteration won't be safe (you only initialize stit
with the first entry outside that loop).

> + }
> + }
> +
> kvmppc_tce_put(stt, entry + i, tce);
> }
>
> @@ -307,6 +602,7 @@ 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)
> @@ -320,6 +616,25 @@ long kvmppc_h_stuff_tce(struct kvm_vcpu *vcpu,
> if (tce_value & (TCE_PCI_WRITE | TCE_PCI_READ))
> return H_PARAMETER;
>
> + stit = list_first_entry_or_null(&stt->iommu_tables,
> + struct kvmppc_spapr_tce_iommu_table, next);
> + if (stit) {
> + if (iommu_tce_clear_param_check(stit->tbl, ioba,
> + tce_value, npages))
> + 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)
> + return ret;

Again do you need some sort of cleanup for partial completion?

> + }
> + }
> + }
> +
> 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 dc1c66fda941..018c7d94a575 100644
> --- a/arch/powerpc/kvm/book3s_64_vio_hv.c
> +++ b/arch/powerpc/kvm/book3s_64_vio_hv.c
> @@ -178,11 +178,104 @@ 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 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 (!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;
> +
> + 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;
> +}
> +
> +long kvmppc_rm_tce_iommu_map(struct kvm_vcpu *vcpu, 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(vcpu->kvm, gpa, &ua, NULL))
> + return H_PARAMETER;
> +
> + mem = mm_iommu_lookup_rm(vcpu->kvm->mm, ua, 1ULL << tbl->it_page_shift);
> + if (!mem)
> + return H_TOO_HARD;
> +
> + if (mm_iommu_ua_to_hpa_rm(mem, ua, &hpa))
> + return H_HARDWARE;
> +
> + pua = (void *) vmalloc_to_phys(pua);
> + if (!pua)
> + return H_HARDWARE;

What circumstances can this fail under? Does it need to be H_TOO_HARD instead?

> +
> + if (mm_iommu_mapped_inc(mem))
> + return H_HARDWARE;
> +
> + 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(vcpu->kvm, tbl, entry);
> +
> + *pua = ua;
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(kvmppc_rm_tce_iommu_map);
> +
> 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); */
> @@ -199,6 +292,33 @@ long kvmppc_rm_h_put_tce(struct kvm_vcpu *vcpu, unsigned long liobn,
> if (ret != H_SUCCESS)
> return ret;
>
> + stit = list_first_entry_or_null(&stt->iommu_tables,
> + struct kvmppc_spapr_tce_iommu_table, next);
> + if (stit) {
> + entry = ioba >> stit->tbl->it_page_shift;
> + gpa = tce & ~(TCE_PCI_READ | TCE_PCI_WRITE);
> + dir = iommu_tce_direction(tce);
> +
> + if (dir == DMA_NONE) {
> + if (iommu_tce_clear_param_check(stit->tbl, ioba, 0, 1))
> + return H_PARAMETER;
> + } else {
> + if (iommu_tce_put_param_check(stit->tbl, ioba, gpa))
> + return H_PARAMETER;
> + }
> +
> + 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, stit->tbl,
> + entry, gpa, dir);
> + if (ret != H_SUCCESS)
> + return ret;
> + }
> + }
> +
> kvmppc_tce_put(stt, ioba >> stt->page_shift, tce);
>
> return H_SUCCESS;
> @@ -237,9 +357,10 @@ 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, tce, ua = 0;
> + unsigned long tces, entry, gpa, tce, ua = 0;
> unsigned long *rmap = NULL;
> bool prereg = false;
> + struct kvmppc_spapr_tce_iommu_table *stit;
>
> stt = kvmppc_find_table(vcpu->kvm, liobn);
> if (!stt)
> @@ -303,17 +424,45 @@ long kvmppc_rm_h_put_tce_indirect(struct kvm_vcpu *vcpu,
> }
> }
>
> + stit = list_first_entry_or_null(&stt->iommu_tables,
> + struct kvmppc_spapr_tce_iommu_table, next);
> +
> for (i = 0; i < npages; ++i) {
> tce = be64_to_cpu(((u64 *)tces)[i]);
>
> ret = kvmppc_tce_validate(stt, tce);
> if (ret != H_SUCCESS)
> goto unlock_exit;
> +
> + if (stit) {
> + gpa = tce & ~(TCE_PCI_READ | TCE_PCI_WRITE);
> + ret = iommu_tce_put_param_check(stit->tbl,
> + ioba + (i << stit->tbl->it_page_shift),
> + gpa);
> + if (ret != H_SUCCESS)
> + goto unlock_exit;
> +
> + }
> }
>
> for (i = 0; i < npages; ++i) {
> tce = be64_to_cpu(((u64 *)tces)[i]);

As noted in the earlier patch this is really dangerous - by reloading
the tce from userspace you've thrown away the verification above.

> + if (stit) {
> + for (i = 0; i < npages; ++i) {
> + 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,
> + stit->tbl, entry + i, gpa,
> + iommu_tce_direction(tce));
> + if (ret != H_SUCCESS)
> + goto unlock_exit;
> + }
> + }
> + }
> +
> kvmppc_tce_put(stt, entry + i, tce);
> }
>
> @@ -330,6 +479,8 @@ 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)
> @@ -343,6 +494,25 @@ long kvmppc_rm_h_stuff_tce(struct kvm_vcpu *vcpu,
> if (tce_value & (TCE_PCI_WRITE | TCE_PCI_READ))
> return H_PARAMETER;
>
> + stit = list_first_entry_or_null(&stt->iommu_tables,
> + struct kvmppc_spapr_tce_iommu_table, next);
> + if (stit) {
> + if (iommu_tce_clear_param_check(stit->tbl, ioba,
> + tce_value, npages))
> + 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 (ret)
> + 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 */

I'm not sure why this one should get a fallthrough comment, when none
of the other cases do.

> + 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(&param, (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);
> +

Is there any particular reason you unwrap the group fd here, but the
table fd inside kvm__spapr_tce_attach_iommu_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);

--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson

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