[PATCH kernel v3] KVM: PPC: Add in-kernel acceleration for VFIO
Alexey Kardashevskiy
aik at ozlabs.ru
Thu Jan 12 19:09:01 AEDT 2017
On 12/01/17 16:04, David Gibson wrote:
> On Tue, Dec 20, 2016 at 05:52:29PM +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, this is done to simplify the cleanup and can be
>> improved later.
>>
>> 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 at ozlabs.ru>
>> ---
>> Changes:
>> 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 obsoletes:
>>
>> [PATCH kernel v2 08/11] KVM: PPC: Pass kvm* to kvmppc_find_table()
>> [PATCH kernel v2 09/11] vfio iommu: Add helpers to (un)register blocking notifiers per group
>> [PATCH kernel v2 11/11] KVM: PPC: Add in-kernel acceleration for VFIO
>>
>>
>> So I have not reposted the whole thing, should have I?
>>
>>
>> btw "F: virt/kvm/vfio.*" is missing MAINTAINERS.
>>
>>
>> ---
>> 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 | 286 +++++++++++++++++++++++++++++
>> arch/powerpc/kvm/book3s_64_vio_hv.c | 178 ++++++++++++++++++
>> arch/powerpc/kvm/powerpc.c | 2 +
>> virt/kvm/vfio.c | 88 +++++++++
>> 8 files changed, 594 insertions(+), 2 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 28350a294b1e..3d281b7ea369 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 0a21c8503974..936138b866e7 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, struct iommu_group *grp);
>> +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 810f74317987..4088da4a575f 100644
>> --- a/include/uapi/linux/kvm.h
>> +++ b/include/uapi/linux/kvm.h
>> @@ -1068,6 +1068,7 @@ 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,
>> @@ -1089,6 +1090,13 @@ 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..008c4aee4df6 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 +43,20 @@
>> #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 (!fn)
>
> I think this should have a WARN_ON(). If the vfio module is gone
> while you still have VFIO groups attached to a KVM table, something
> has gone horribly wrong.
>
>> + return;
>> +
>> + fn(vfio_group);
>> +
>> + symbol_put(vfio_group_put_external_user);
>> +}
>>
>> static unsigned long kvmppc_tce_pages(unsigned long iommu_pages)
>> {
>> @@ -90,6 +108,99 @@ 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);
>> +
>> + 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);
>> +
>> + iommu_table_put(stit->tbl);
>> + kvm_vfio_group_put_external_user(stit->group);
>> +
>> + 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 iommu_group *grp)
>
> Isn't passing both the vfio_group and the iommu_group redundant?
vfio_group struct is internal to the vfio driver and there is no API to get
the iommu_group pointer from it.
>
>> +{
>> + struct kvmppc_spapr_tce_table *stt = NULL;
>> + bool found = false;
>> + struct iommu_table *tbl = NULL;
>> + struct iommu_table_group *table_group;
>> + long i;
>> + struct kvmppc_spapr_tce_iommu_table *stit;
>> + struct fd f;
>> +
>> + f = fdget(tablefd);
>> + if (!f.file)
>> + return -EBADF;
>> +
>> + 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)
>> + return -ENODEV;
>
> Not entirely sure if ENODEV is the right error, but I can't
> immediately think of a better one.
>
>> + table_group = iommu_group_get_iommudata(grp);
>> + if (!table_group)
>> + return -EFAULT;
>
> EFAULT is usually only returned when you pass a syscall a bad pointer,
> which doesn't look to be the case here. What situation does this
> error path actually represent?
"something went terribly wrong".
>
>> +
>> + for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i) {
>> + struct iommu_table *tbltmp = table_group->tables[i];
>> +
>> + if (!tbltmp)
>> + continue;
>> +
>> + if ((tbltmp->it_page_shift == stt->page_shift) &&
>> + (tbltmp->it_offset == stt->offset)) {
>> + tbl = tbltmp;
>> + break;
>> + }
>> + }
>> + if (!tbl)
>> + return -ENODEV;
>> +
>> + iommu_table_get(tbl);
>> +
>> + stit = kzalloc(sizeof(*stit), GFP_KERNEL);
>> + stit->tbl = tbl;
>> + stit->group = group;
>> +
>> + list_add_rcu(&stit->next, &stt->iommu_tables);
>
> Won't this add a separate stit entry for each group attached to the
> LIOBN, even if those groups share a single hardware iommu table -
> which is the likely case if those groups have all been put into the
> same container.
Correct. I am planning on optimizing this later.
>
>> + return 0;
>> +}
>> +
>> static void release_spapr_tce_table(struct rcu_head *head)
>> {
>> struct kvmppc_spapr_tce_table *stt = container_of(head,
>> @@ -132,6 +243,8 @@ 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 +294,7 @@ 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 +323,161 @@ 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;
>> +
>> + mem = mm_iommu_lookup(kvm->mm, *pua, pgsize);
>> + if (!mem)
>> + return H_HARDWARE;
>
> IIUC, this error represents trying to unmap a page from the vIOMMU,
> and discovering that it wasn't preregistered in the first place, which
> shouldn't happen. So would a WARN_ON() make sense here as well as the
> H_HARDWARE.
>
>> + 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;
>> +
>> + if (iommu_tce_xchg(tbl, entry, &hpa, &dir))
>> + return H_HARDWARE;
>> +
>> + if (dir == DMA_NONE)
>> + return H_SUCCESS;
>> +
>> + return kvmppc_tce_iommu_mapped_dec(kvm, tbl, entry);
>> +}
>> +
>> +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_HARDWARE;
>
> This would represent the guest trying to map a mad GPA, yes? In which
> case H_HARDWARE doesn't seem right. H_PARAMETER or H_PERMISSION, maybe.
>
>> + mem = mm_iommu_lookup(kvm->mm, ua, 1ULL << tbl->it_page_shift);
>> + if (!mem)
>> + return H_HARDWARE;
>
> Here H_HARDWARE seems right. IIUC this represents the guest trying to
> map an address which wasn't pre-registered. That would indicate a bug
> in qemu, which is hardware as far as the guest is concerned.
>
>> +
>> + if (mm_iommu_ua_to_hpa(mem, ua, &hpa))
>> + return H_HARDWARE;
>
> Not sure what this case represents.
Preregistered memory not being able to translate userspace address to a
host physical. In virtual mode it is a simple bounds checker, in real mode
it also includes vmalloc_to_phys() failure.
>
>> + if (mm_iommu_mapped_inc(mem))
>> + return H_HARDWARE;
>
> Or this.
A preregistered memory area is in a process of disposal, no new mappings
are allowed.
>
>> + 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_iommu(struct kvm_vcpu *vcpu,
>> + struct iommu_table *tbl,
>> + unsigned long liobn, unsigned long ioba,
>> + unsigned long tce)
>> +{
>> + long idx, ret = H_HARDWARE;
>> + const unsigned long entry = ioba >> tbl->it_page_shift;
>> + const unsigned long gpa = tce & ~(TCE_PCI_READ | TCE_PCI_WRITE);
>> + const enum dma_data_direction dir = iommu_tce_direction(tce);
>> +
>> + /* Clear TCE */
>> + if (dir == DMA_NONE) {
>> + if (iommu_tce_clear_param_check(tbl, ioba, 0, 1))
>> + return H_PARAMETER;
>> +
>> + return kvmppc_tce_iommu_unmap(vcpu->kvm, tbl, entry);
>> + }
>> +
>> + /* Put TCE */
>> + if (iommu_tce_put_param_check(tbl, ioba, gpa))
>> + return H_PARAMETER;
>> +
>> + idx = srcu_read_lock(&vcpu->kvm->srcu);
>> + ret = kvmppc_tce_iommu_map(vcpu->kvm, tbl, entry, gpa, dir);
>> + srcu_read_unlock(&vcpu->kvm->srcu, idx);
>> +
>> + return ret;
>> +}
>> +
>> +static long kvmppc_h_put_tce_indirect_iommu(struct kvm_vcpu *vcpu,
>> + struct iommu_table *tbl, unsigned long ioba,
>> + u64 __user *tces, unsigned long npages)
>> +{
>> + unsigned long i, ret, tce, gpa;
>> + const unsigned long entry = ioba >> tbl->it_page_shift;
>> +
>> + for (i = 0; i < npages; ++i) {
>> + gpa = be64_to_cpu(tces[i]) & ~(TCE_PCI_READ | TCE_PCI_WRITE);
>
> IIUC this is the virtual mode, not the real mode version. In which
> case you shouldn't be accessing tces[i] (a userspace pointeR) directly
> bit should instead be using get_user().
>
>> + if (iommu_tce_put_param_check(tbl, ioba +
>> + (i << tbl->it_page_shift), gpa))
>> + return H_PARAMETER;
>> + }
>> +
>> + for (i = 0; i < npages; ++i) {
>> + tce = be64_to_cpu(tces[i]);
>> + gpa = tce & ~(TCE_PCI_READ | TCE_PCI_WRITE);
>> +
>> + ret = kvmppc_tce_iommu_map(vcpu->kvm, tbl, entry + i, gpa,
>> + iommu_tce_direction(tce));
>> + if (ret != H_SUCCESS)
>> + return ret;
>> + }
>> +
>> + return H_SUCCESS;
>> +}
>> +
>> +long kvmppc_h_stuff_tce_iommu(struct kvm_vcpu *vcpu,
>> + struct iommu_table *tbl,
>> + unsigned long liobn, unsigned long ioba,
>> + unsigned long tce_value, unsigned long npages)
>> +{
>> + unsigned long i;
>> + const unsigned long entry = ioba >> tbl->it_page_shift;
>> +
>> + if (iommu_tce_clear_param_check(tbl, ioba, tce_value, npages))
>> + return H_PARAMETER;
>> +
>> + for (i = 0; i < npages; ++i)
>> + kvmppc_tce_iommu_unmap(vcpu->kvm, tbl, entry + i);
>> +
>> + return H_SUCCESS;
>> +}
>> +
>> 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;
>> + struct kvmppc_spapr_tce_iommu_table *stit;
>>
>> /* udbg_printf("H_PUT_TCE(): liobn=0x%lx ioba=0x%lx, tce=0x%lx\n", */
>> /* liobn, ioba, tce); */
>> @@ -230,6 +494,12 @@ long kvmppc_h_put_tce(struct kvm_vcpu *vcpu, unsigned long liobn,
>> if (ret != H_SUCCESS)
>> return ret;
>>
>> + list_for_each_entry_lockless(stit, &stt->iommu_tables, next) {
>
> As noted above, AFAICT there is one stit per group, rather than per
> backend IOMMU table, so if there are multiple groups in the same
> container (and therefore attached to the same LIOBN), won't this mean
> we duplicate this operation a bunch of times?
>
>> + ret = kvmppc_h_put_tce_iommu(vcpu, stit->tbl, liobn, ioba, tce);
>> + if (ret != H_SUCCESS)
>> + return ret;
>> + }
>> +
>> kvmppc_tce_put(stt, ioba >> stt->page_shift, tce);
>>
>> return H_SUCCESS;
>> @@ -245,6 +515,7 @@ 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)
>> @@ -272,6 +543,13 @@ long kvmppc_h_put_tce_indirect(struct kvm_vcpu *vcpu,
>> }
>> tces = (u64 __user *) ua;
>>
>> + list_for_each_entry_lockless(stit, &stt->iommu_tables, next) {
>> + ret = kvmppc_h_put_tce_indirect_iommu(vcpu,
>> + stit->tbl, ioba, tces, npages);
>> + if (ret != H_SUCCESS)
>> + goto unlock_exit;
>
> Hmm, I don't suppose you could simplify things by not having a
> put_tce_indirect() version of the whole backend iommu mapping
> function, but just a single-TCE version, and instead looping across
> the backend IOMMU tables as you put each indirect entry in .
>
>> + }
>> +
>> for (i = 0; i < npages; ++i) {
>> if (get_user(tce, tces + i)) {
>> ret = H_TOO_HARD;
>> @@ -299,6 +577,7 @@ 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 +591,13 @@ 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) {
>> + ret = kvmppc_h_stuff_tce_iommu(vcpu, stit->tbl, liobn, ioba,
>> + tce_value, npages);
>> + 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 8a6834e6e1c8..4d6f01712a6d 100644
>> --- a/arch/powerpc/kvm/book3s_64_vio_hv.c
>> +++ b/arch/powerpc/kvm/book3s_64_vio_hv.c
>> @@ -190,11 +190,165 @@ static struct mm_iommu_table_group_mem_t *kvmppc_rm_iommu_lookup(
>> return mm_iommu_lookup_rm(vcpu->kvm->mm, ua, size);
>> }
>>
>> +static long kvmppc_rm_tce_iommu_mapped_dec(struct kvm_vcpu *vcpu,
>> + 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_SUCCESS;
>
> What case is this? Not being able to find the userspace duesn't sound
> like a success.
>
>> + pua = (void *) vmalloc_to_phys(pua);
>> + if (!pua)
>> + return H_SUCCESS;
>
> And again..
>
>> + mem = kvmppc_rm_iommu_lookup(vcpu, *pua, pgsize);
>> + if (!mem)
>> + return H_HARDWARE;
>
> Should this have a WARN_ON?
>
>> + mm_iommu_mapped_dec(mem);
>> +
>> + *pua = 0;
>> +
>> + return H_SUCCESS;
>> +}
>> +
>> +static long kvmppc_rm_tce_iommu_unmap(struct kvm_vcpu *vcpu,
>> + struct iommu_table *tbl, unsigned long entry)
>> +{
>> + enum dma_data_direction dir = DMA_NONE;
>> + unsigned long hpa = 0;
>> +
>> + if (iommu_tce_xchg_rm(tbl, entry, &hpa, &dir))
>> + return H_HARDWARE;
>> +
>> + if (dir == DMA_NONE)
>> + return H_SUCCESS;
>> +
>> + return kvmppc_rm_tce_iommu_mapped_dec(vcpu, tbl, entry);
>> +}
>> +
>> +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_HARDWARE;
>
> Again H_HARDWARE doesn't seem right here.
>
>> + mem = kvmppc_rm_iommu_lookup(vcpu, ua, 1ULL << tbl->it_page_shift);
>> + if (!mem)
>> + return H_HARDWARE;
>> +
>> + if (mm_iommu_ua_to_hpa_rm(mem, ua, &hpa))
>> + return H_HARDWARE;
>> +
>> + pua = (void *) vmalloc_to_phys(pua);
>> + if (!pua)
>> + return H_HARDWARE;
>> +
>> + 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, tbl, entry);
>> +
>> + *pua = ua;
>> +
>> + return 0;
>> +}
>> +EXPORT_SYMBOL_GPL(kvmppc_rm_tce_iommu_map);
>> +
>> +static long kvmppc_rm_h_put_tce_iommu(struct kvm_vcpu *vcpu,
>> + struct iommu_table *tbl, unsigned long liobn,
>> + unsigned long ioba, unsigned long tce)
>> +{
>> + const unsigned long entry = ioba >> tbl->it_page_shift;
>> + const unsigned long gpa = tce & ~(TCE_PCI_READ | TCE_PCI_WRITE);
>> + const enum dma_data_direction dir = iommu_tce_direction(tce);
>> +
>> + /* Clear TCE */
>> + if (dir == DMA_NONE) {
>> + if (iommu_tce_clear_param_check(tbl, ioba, 0, 1))
>> + return H_PARAMETER;
>> +
>> + return kvmppc_rm_tce_iommu_unmap(vcpu, tbl, entry);
>> + }
>> +
>> + /* Put TCE */
>> + if (iommu_tce_put_param_check(tbl, ioba, gpa))
>> + return H_PARAMETER;
>> +
>> + return kvmppc_rm_tce_iommu_map(vcpu, tbl, entry, gpa, dir);
>> +}
>> +
>> +static long kvmppc_rm_h_put_tce_indirect_iommu(struct kvm_vcpu *vcpu,
>> + struct iommu_table *tbl, unsigned long ioba,
>> + u64 *tces, unsigned long npages)
>> +{
>> + unsigned long i, ret, tce, gpa;
>> + const unsigned long entry = ioba >> tbl->it_page_shift;
>> +
>> + for (i = 0; i < npages; ++i) {
>> + gpa = be64_to_cpu(tces[i]) & ~(TCE_PCI_READ | TCE_PCI_WRITE);
>> +
>> + if (iommu_tce_put_param_check(tbl, ioba +
>> + (i << tbl->it_page_shift), gpa))
>> + return H_PARAMETER;
>> + }
>> +
>> + for (i = 0; i < npages; ++i) {
>> + tce = be64_to_cpu(tces[i]);
>> + gpa = tce & ~(TCE_PCI_READ | TCE_PCI_WRITE);
>> +
>> + ret = kvmppc_rm_tce_iommu_map(vcpu, tbl, entry + i, gpa,
>> + iommu_tce_direction(tce));
>> + if (ret != H_SUCCESS)
>> + return ret;
>> + }
>> +
>> + return H_SUCCESS;
>> +}
>> +
>> +static long kvmppc_rm_h_stuff_tce_iommu(struct kvm_vcpu *vcpu,
>> + struct iommu_table *tbl,
>> + unsigned long liobn, unsigned long ioba,
>> + unsigned long tce_value, unsigned long npages)
>> +{
>> + unsigned long i;
>> + const unsigned long entry = ioba >> tbl->it_page_shift;
>> +
>> + if (iommu_tce_clear_param_check(tbl, ioba, tce_value, npages))
>> + return H_PARAMETER;
>> +
>> + for (i = 0; i < npages; ++i)
>> + kvmppc_rm_tce_iommu_unmap(vcpu, tbl, entry + i);
>> +
>> + return H_SUCCESS;
>> +}
>> +
>> 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;
>>
>> /* udbg_printf("H_PUT_TCE(): liobn=0x%lx ioba=0x%lx, tce=0x%lx\n", */
>> /* liobn, ioba, tce); */
>> @@ -211,6 +365,13 @@ long kvmppc_rm_h_put_tce(struct kvm_vcpu *vcpu, unsigned long liobn,
>> if (ret != H_SUCCESS)
>> return ret;
>>
>> + list_for_each_entry_lockless(stit, &stt->iommu_tables, next) {
>> + ret = kvmppc_rm_h_put_tce_iommu(vcpu, stit->tbl,
>> + liobn, ioba, tce);
>> + if (ret != H_SUCCESS)
>> + return ret;
>> + }
>> +
>> kvmppc_tce_put(stt, ioba >> stt->page_shift, tce);
>>
>> return H_SUCCESS;
>> @@ -278,6 +439,7 @@ long kvmppc_rm_h_put_tce_indirect(struct kvm_vcpu *vcpu,
>> * depend on hpt.
>> */
>> struct mm_iommu_table_group_mem_t *mem;
>> + struct kvmppc_spapr_tce_iommu_table *stit;
>>
>> if (kvmppc_gpa_to_ua(vcpu->kvm, tce_list, &ua, NULL))
>> return H_TOO_HARD;
>> @@ -285,6 +447,13 @@ long kvmppc_rm_h_put_tce_indirect(struct kvm_vcpu *vcpu,
>> mem = kvmppc_rm_iommu_lookup(vcpu, ua, IOMMU_PAGE_SIZE_4K);
>> if (!mem || mm_iommu_ua_to_hpa_rm(mem, ua, &tces))
>> return H_TOO_HARD;
>> +
>> + list_for_each_entry_lockless(stit, &stt->iommu_tables, next) {
>> + ret = kvmppc_rm_h_put_tce_indirect_iommu(vcpu,
>> + stit->tbl, ioba, (u64 *)tces, npages);
>> + if (ret != H_SUCCESS)
>> + return ret;
>> + }
>> } else {
>> /*
>> * This is emulated devices case.
>> @@ -334,6 +503,8 @@ 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)
>> @@ -347,6 +518,13 @@ 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) {
>> + ret = kvmppc_rm_h_stuff_tce_iommu(vcpu, stit->tbl,
>> + liobn, ioba, tce_value, npages);
>> + 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 70963c845e96..0e555ba998c0 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_ALLOC_HTAB:
>> case KVM_CAP_PPC_RTAS:
>> case KVM_CAP_PPC_FIXUP_HCALL:
>> diff --git a/virt/kvm/vfio.c b/virt/kvm/vfio.c
>> index d32f239eb471..3181054c8ff7 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;
>> @@ -89,6 +93,22 @@ static bool kvm_vfio_group_is_coherent(struct vfio_group *vfio_group)
>> return ret > 0;
>> }
>>
>> +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;
>> +}
>> +
>> /*
>> * 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
>> @@ -211,6 +231,9 @@ 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 +241,65 @@ 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) {
>> + int group_id;
>> + struct iommu_group *grp;
>> +
>> + if (kvg->vfio_group != vfio_group)
>> + continue;
>> +
>> + group_id = kvm_vfio_external_user_iommu_id(
>> + kvg->vfio_group);
>> + grp = iommu_group_get_by_id(group_id);
>> + if (!grp) {
>> + ret = -EFAULT;
>> + break;
>> + }
>> +
>> + ret = kvm_spapr_tce_attach_iommu_group(dev->kvm,
>> + param.tablefd, vfio_group, grp);
>> +
>> + iommu_group_put(grp);
>> + break;
>> + }
>> +
>> + mutex_unlock(&kv->lock);
>> +
>> + return ret;
>> + }
>> +#endif /* CONFIG_SPAPR_TCE_IOMMU */
>> }
>
> Don't you also need to add something to the KVM_DEV_VFIO_GROUP_DEL
> path to detach the group from all LIOBNs, Or else just fail if if
> there are LIOBNs attached. I think it would be a qemu bug not to
> detach the LIOBNs before removing the group, but we stil need to
> protect the host in that case.
Yeah, this bit is a bit tricky/ugly.
kvm_spapr_tce_liobn_release_iommu_group() (called from
kvm_spapr_tce_fops::release()) drops references when a group is removed
from the VFIO KVM device so there is no KVM_DEV_VFIO_GROUP_UNSET_SPAPR_TCE
and no action from QEMU is required.
>>
>> return -ENXIO;
>> @@ -242,6 +324,9 @@ 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 +342,9 @@ 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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