Re: [Qemu-devel] [PATCH v8 9/9] intel_iommu: enable remote IOTLB

["Michael S. Tsirkin" <mst@redhat.com>]

On Thu, Apr 06, 2017 at 03:08:44PM +0800, Peter Xu wrote:
> This patch is based on Aviv Ben-David (<bd.aviv@gmail.com>)'s patch
> upstream:
> 
>   "IOMMU: enable intel_iommu map and unmap notifiers"
>   https://lists.gnu.org/archive/html/qemu-devel/2016-11/msg01453.html
> 
> However I removed/fixed some content, and added my own codes.
> 
> Instead of translate() every page for iotlb invalidations (which is
> slower), we walk the pages when needed and notify in a hook function.
> 
> This patch enables vfio devices for VT-d emulation.
> 
> And, since we already have vhost DMAR support via device-iotlb, a
> natural benefit that this patch brings is that vt-d enabled vhost can
> live even without ATS capability now. Though more tests are needed.
> 
> Signed-off-by: Aviv Ben-David <bdaviv@cs.technion.ac.il>
> Reviewed-by: Jason Wang <jasowang@redhat.com>
> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
> Signed-off-by: Peter Xu <peterx@redhat.com>

Reviewed-by: Michael S. Tsirkin <mst@redhat.com>

> ---
>  hw/i386/intel_iommu.c          | 191 ++++++++++++++++++++++++++++++++++++++---
>  hw/i386/intel_iommu_internal.h |   1 +
>  hw/i386/trace-events           |   1 +
>  include/hw/i386/intel_iommu.h  |   8 ++
>  4 files changed, 188 insertions(+), 13 deletions(-)
> 
> diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
> index f7dec82..02f047c 100644
> --- a/hw/i386/intel_iommu.c
> +++ b/hw/i386/intel_iommu.c
> @@ -806,7 +806,8 @@ next:
>   * @private: private data for the hook function
>   */
>  static int vtd_page_walk(VTDContextEntry *ce, uint64_t start, uint64_t end,
> -                         vtd_page_walk_hook hook_fn, void *private)
> +                         vtd_page_walk_hook hook_fn, void *private,
> +                         bool notify_unmap)
>  {
>      dma_addr_t addr = vtd_get_slpt_base_from_context(ce);
>      uint32_t level = vtd_get_level_from_context_entry(ce);
> @@ -821,7 +822,7 @@ static int vtd_page_walk(VTDContextEntry *ce, uint64_t start, uint64_t end,
>      }
>  
>      return vtd_page_walk_level(addr, start, end, hook_fn, private,
> -                               level, true, true, false);
> +                               level, true, true, notify_unmap);
>  }
>  
>  /* Map a device to its corresponding domain (context-entry) */
> @@ -1038,6 +1039,15 @@ static void vtd_interrupt_remap_table_setup(IntelIOMMUState *s)
>                  s->intr_root, s->intr_size);
>  }
>  
> +static void vtd_iommu_replay_all(IntelIOMMUState *s)
> +{
> +    IntelIOMMUNotifierNode *node;
> +
> +    QLIST_FOREACH(node, &s->notifiers_list, next) {
> +        memory_region_iommu_replay_all(&node->vtd_as->iommu);
> +    }
> +}
> +
>  static void vtd_context_global_invalidate(IntelIOMMUState *s)
>  {
>      trace_vtd_inv_desc_cc_global();
> @@ -1045,6 +1055,14 @@ static void vtd_context_global_invalidate(IntelIOMMUState *s)
>      if (s->context_cache_gen == VTD_CONTEXT_CACHE_GEN_MAX) {
>          vtd_reset_context_cache(s);
>      }
> +    /*
> +     * From VT-d spec 6.5.2.1, a global context entry invalidation
> +     * should be followed by a IOTLB global invalidation, so we should
> +     * be safe even without this. Hoewever, let's replay the region as
> +     * well to be safer, and go back here when we need finer tunes for
> +     * VT-d emulation codes.
> +     */
> +    vtd_iommu_replay_all(s);
>  }
>  
>  
> @@ -1111,6 +1129,16 @@ static void vtd_context_device_invalidate(IntelIOMMUState *s,
>                  trace_vtd_inv_desc_cc_device(bus_n, VTD_PCI_SLOT(devfn_it),
>                                               VTD_PCI_FUNC(devfn_it));
>                  vtd_as->context_cache_entry.context_cache_gen = 0;
> +                /*
> +                 * So a device is moving out of (or moving into) a
> +                 * domain, a replay() suites here to notify all the
> +                 * IOMMU_NOTIFIER_MAP registers about this change.
> +                 * This won't bring bad even if we have no such
> +                 * notifier registered - the IOMMU notification
> +                 * framework will skip MAP notifications if that
> +                 * happened.
> +                 */
> +                memory_region_iommu_replay_all(&vtd_as->iommu);
>              }
>          }
>      }
> @@ -1152,12 +1180,53 @@ static void vtd_iotlb_global_invalidate(IntelIOMMUState *s)
>  {
>      trace_vtd_iotlb_reset("global invalidation recved");
>      vtd_reset_iotlb(s);
> +    vtd_iommu_replay_all(s);
>  }
>  
>  static void vtd_iotlb_domain_invalidate(IntelIOMMUState *s, uint16_t domain_id)
>  {
> +    IntelIOMMUNotifierNode *node;
> +    VTDContextEntry ce;
> +    VTDAddressSpace *vtd_as;
> +
>      g_hash_table_foreach_remove(s->iotlb, vtd_hash_remove_by_domain,
>                                  &domain_id);
> +
> +    QLIST_FOREACH(node, &s->notifiers_list, next) {
> +        vtd_as = node->vtd_as;
> +        if (!vtd_dev_to_context_entry(s, pci_bus_num(vtd_as->bus),
> +                                      vtd_as->devfn, &ce) &&
> +            domain_id == VTD_CONTEXT_ENTRY_DID(ce.hi)) {
> +            memory_region_iommu_replay_all(&vtd_as->iommu);
> +        }
> +    }
> +}
> +
> +static int vtd_page_invalidate_notify_hook(IOMMUTLBEntry *entry,
> +                                           void *private)
> +{
> +    memory_region_notify_iommu((MemoryRegion *)private, *entry);
> +    return 0;
> +}
> +
> +static void vtd_iotlb_page_invalidate_notify(IntelIOMMUState *s,
> +                                           uint16_t domain_id, hwaddr addr,
> +                                           uint8_t am)
> +{
> +    IntelIOMMUNotifierNode *node;
> +    VTDContextEntry ce;
> +    int ret;
> +
> +    QLIST_FOREACH(node, &(s->notifiers_list), next) {
> +        VTDAddressSpace *vtd_as = node->vtd_as;
> +        ret = vtd_dev_to_context_entry(s, pci_bus_num(vtd_as->bus),
> +                                       vtd_as->devfn, &ce);
> +        if (!ret && domain_id == VTD_CONTEXT_ENTRY_DID(ce.hi)) {
> +            vtd_page_walk(&ce, addr, addr + (1 << am) * VTD_PAGE_SIZE,
> +                          vtd_page_invalidate_notify_hook,
> +                          (void *)&vtd_as->iommu, true);
> +        }
> +    }
>  }
>  
>  static void vtd_iotlb_page_invalidate(IntelIOMMUState *s, uint16_t domain_id,
> @@ -1170,6 +1239,7 @@ static void vtd_iotlb_page_invalidate(IntelIOMMUState *s, uint16_t domain_id,
>      info.addr = addr;
>      info.mask = ~((1 << am) - 1);
>      g_hash_table_foreach_remove(s->iotlb, vtd_hash_remove_by_page, &info);
> +    vtd_iotlb_page_invalidate_notify(s, domain_id, addr, am);
>  }
>  
>  /* Flush IOTLB
> @@ -2187,15 +2257,33 @@ static void vtd_iommu_notify_flag_changed(MemoryRegion *iommu,
>                                            IOMMUNotifierFlag new)
>  {
>      VTDAddressSpace *vtd_as = container_of(iommu, VTDAddressSpace, iommu);
> +    IntelIOMMUState *s = vtd_as->iommu_state;
> +    IntelIOMMUNotifierNode *node = NULL;
> +    IntelIOMMUNotifierNode *next_node = NULL;
>  
> -    if (new & IOMMU_NOTIFIER_MAP) {
> -        error_report("Device at bus %s addr %02x.%d requires iommu "
> -                     "notifier which is currently not supported by "
> -                     "intel-iommu emulation",
> -                     vtd_as->bus->qbus.name, PCI_SLOT(vtd_as->devfn),
> -                     PCI_FUNC(vtd_as->devfn));
> +    if (!s->caching_mode && new & IOMMU_NOTIFIER_MAP) {
> +        error_report("We need to set cache_mode=1 for intel-iommu to enable "
> +                     "device assignment with IOMMU protection.");
>          exit(1);
>      }
> +
> +    if (old == IOMMU_NOTIFIER_NONE) {
> +        node = g_malloc0(sizeof(*node));
> +        node->vtd_as = vtd_as;
> +        QLIST_INSERT_HEAD(&s->notifiers_list, node, next);
> +        return;
> +    }
> +
> +    /* update notifier node with new flags */
> +    QLIST_FOREACH_SAFE(node, &s->notifiers_list, next, next_node) {
> +        if (node->vtd_as == vtd_as) {
> +            if (new == IOMMU_NOTIFIER_NONE) {
> +                QLIST_REMOVE(node, next);
> +                g_free(node);
> +            }
> +            return;
> +        }
> +    }
>  }
>  
>  static const VMStateDescription vtd_vmstate = {
> @@ -2613,6 +2701,74 @@ VTDAddressSpace *vtd_find_add_as(IntelIOMMUState *s, PCIBus *bus, int devfn)
>      return vtd_dev_as;
>  }
>  
> +/* Unmap the whole range in the notifier's scope. */
> +static void vtd_address_space_unmap(VTDAddressSpace *as, IOMMUNotifier *n)
> +{
> +    IOMMUTLBEntry entry;
> +    hwaddr size;
> +    hwaddr start = n->start;
> +    hwaddr end = n->end;
> +
> +    /*
> +     * Note: all the codes in this function has a assumption that IOVA
> +     * bits are no more than VTD_MGAW bits (which is restricted by
> +     * VT-d spec), otherwise we need to consider overflow of 64 bits.
> +     */
> +
> +    if (end > VTD_ADDRESS_SIZE) {
> +        /*
> +         * Don't need to unmap regions that is bigger than the whole
> +         * VT-d supported address space size
> +         */
> +        end = VTD_ADDRESS_SIZE;
> +    }
> +
> +    assert(start <= end);
> +    size = end - start;
> +
> +    if (ctpop64(size) != 1) {
> +        /*
> +         * This size cannot format a correct mask. Let's enlarge it to
> +         * suite the minimum available mask.
> +         */
> +        int n = 64 - clz64(size);
> +        if (n > VTD_MGAW) {
> +            /* should not happen, but in case it happens, limit it */
> +            n = VTD_MGAW;
> +        }
> +        size = 1ULL << n;
> +    }
> +
> +    entry.target_as = &address_space_memory;
> +    /* Adjust iova for the size */
> +    entry.iova = n->start & ~(size - 1);
> +    /* This field is meaningless for unmap */
> +    entry.translated_addr = 0;
> +    entry.perm = IOMMU_NONE;
> +    entry.addr_mask = size - 1;
> +
> +    trace_vtd_as_unmap_whole(pci_bus_num(as->bus),
> +                             VTD_PCI_SLOT(as->devfn),
> +                             VTD_PCI_FUNC(as->devfn),
> +                             entry.iova, size);
> +
> +    memory_region_notify_one(n, &entry);
> +}
> +
> +static void vtd_address_space_unmap_all(IntelIOMMUState *s)
> +{
> +    IntelIOMMUNotifierNode *node;
> +    VTDAddressSpace *vtd_as;
> +    IOMMUNotifier *n;
> +
> +    QLIST_FOREACH(node, &s->notifiers_list, next) {
> +        vtd_as = node->vtd_as;
> +        IOMMU_NOTIFIER_FOREACH(n, &vtd_as->iommu) {
> +            vtd_address_space_unmap(vtd_as, n);
> +        }
> +    }
> +}
> +
>  static int vtd_replay_hook(IOMMUTLBEntry *entry, void *private)
>  {
>      memory_region_notify_one((IOMMUNotifier *)private, entry);
> @@ -2626,16 +2782,19 @@ static void vtd_iommu_replay(MemoryRegion *mr, IOMMUNotifier *n)
>      uint8_t bus_n = pci_bus_num(vtd_as->bus);
>      VTDContextEntry ce;
>  
> +    /*
> +     * The replay can be triggered by either a invalidation or a newly
> +     * created entry. No matter what, we release existing mappings
> +     * (it means flushing caches for UNMAP-only registers).
> +     */
> +    vtd_address_space_unmap(vtd_as, n);
> +
>      if (vtd_dev_to_context_entry(s, bus_n, vtd_as->devfn, &ce) == 0) {
> -        /*
> -         * Scanned a valid context entry, walk over the pages and
> -         * notify when needed.
> -         */
>          trace_vtd_replay_ce_valid(bus_n, PCI_SLOT(vtd_as->devfn),
>                                    PCI_FUNC(vtd_as->devfn),
>                                    VTD_CONTEXT_ENTRY_DID(ce.hi),
>                                    ce.hi, ce.lo);
> -        vtd_page_walk(&ce, 0, ~0ULL, vtd_replay_hook, (void *)n);
> +        vtd_page_walk(&ce, 0, ~0ULL, vtd_replay_hook, (void *)n, false);
>      } else {
>          trace_vtd_replay_ce_invalid(bus_n, PCI_SLOT(vtd_as->devfn),
>                                      PCI_FUNC(vtd_as->devfn));
> @@ -2754,6 +2913,11 @@ static void vtd_reset(DeviceState *dev)
>  
>      VTD_DPRINTF(GENERAL, "");
>      vtd_init(s);
> +
> +    /*
> +     * When device reset, throw away all mappings and external caches
> +     */
> +    vtd_address_space_unmap_all(s);
>  }
>  
>  static AddressSpace *vtd_host_dma_iommu(PCIBus *bus, void *opaque, int devfn)
> @@ -2817,6 +2981,7 @@ static void vtd_realize(DeviceState *dev, Error **errp)
>          return;
>      }
>  
> +    QLIST_INIT(&s->notifiers_list);
>      memset(s->vtd_as_by_bus_num, 0, sizeof(s->vtd_as_by_bus_num));
>      memory_region_init_io(&s->csrmem, OBJECT(s), &vtd_mem_ops, s,
>                            "intel_iommu", DMAR_REG_SIZE);
> diff --git a/hw/i386/intel_iommu_internal.h b/hw/i386/intel_iommu_internal.h
> index 4104121..29d6707 100644
> --- a/hw/i386/intel_iommu_internal.h
> +++ b/hw/i386/intel_iommu_internal.h
> @@ -197,6 +197,7 @@
>  #define VTD_DOMAIN_ID_MASK          ((1UL << VTD_DOMAIN_ID_SHIFT) - 1)
>  #define VTD_CAP_ND                  (((VTD_DOMAIN_ID_SHIFT - 4) / 2) & 7ULL)
>  #define VTD_MGAW                    39  /* Maximum Guest Address Width */
> +#define VTD_ADDRESS_SIZE            (1ULL << VTD_MGAW)
>  #define VTD_CAP_MGAW                (((VTD_MGAW - 1) & 0x3fULL) << 16)
>  #define VTD_MAMV                    18ULL
>  #define VTD_CAP_MAMV                (VTD_MAMV << 48)
> diff --git a/hw/i386/trace-events b/hw/i386/trace-events
> index 3c3a167..04a6980 100644
> --- a/hw/i386/trace-events
> +++ b/hw/i386/trace-events
> @@ -37,6 +37,7 @@ vtd_page_walk_skip_read(uint64_t iova, uint64_t next) "Page walk skip iova 0x%"P
>  vtd_page_walk_skip_perm(uint64_t iova, uint64_t next) "Page walk skip iova 0x%"PRIx64" - 0x%"PRIx64" due to perm empty"
>  vtd_page_walk_skip_reserve(uint64_t iova, uint64_t next) "Page walk skip iova 0x%"PRIx64" - 0x%"PRIx64" due to rsrv set"
>  vtd_switch_address_space(uint8_t bus, uint8_t slot, uint8_t fn, bool on) "Device %02x:%02x.%x switching address space (iommu enabled=%d)"
> +vtd_as_unmap_whole(uint8_t bus, uint8_t slot, uint8_t fn, uint64_t iova, uint64_t size) "Device %02x:%02x.%x start 0x%"PRIx64" size 0x%"PRIx64
>  
>  # hw/i386/amd_iommu.c
>  amdvi_evntlog_fail(uint64_t addr, uint32_t head) "error: fail to write at addr 0x%"PRIx64" +  offset 0x%"PRIx32
> diff --git a/include/hw/i386/intel_iommu.h b/include/hw/i386/intel_iommu.h
> index 8f212a1..3e51876 100644
> --- a/include/hw/i386/intel_iommu.h
> +++ b/include/hw/i386/intel_iommu.h
> @@ -63,6 +63,7 @@ typedef union VTD_IR_TableEntry VTD_IR_TableEntry;
>  typedef union VTD_IR_MSIAddress VTD_IR_MSIAddress;
>  typedef struct VTDIrq VTDIrq;
>  typedef struct VTD_MSIMessage VTD_MSIMessage;
> +typedef struct IntelIOMMUNotifierNode IntelIOMMUNotifierNode;
>  
>  /* Context-Entry */
>  struct VTDContextEntry {
> @@ -249,6 +250,11 @@ struct VTD_MSIMessage {
>  /* When IR is enabled, all MSI/MSI-X data bits should be zero */
>  #define VTD_IR_MSI_DATA          (0)
>  
> +struct IntelIOMMUNotifierNode {
> +    VTDAddressSpace *vtd_as;
> +    QLIST_ENTRY(IntelIOMMUNotifierNode) next;
> +};
> +
>  /* The iommu (DMAR) device state struct */
>  struct IntelIOMMUState {
>      X86IOMMUState x86_iommu;
> @@ -286,6 +292,8 @@ struct IntelIOMMUState {
>      MemoryRegionIOMMUOps iommu_ops;
>      GHashTable *vtd_as_by_busptr;   /* VTDBus objects indexed by PCIBus* reference */
>      VTDBus *vtd_as_by_bus_num[VTD_PCI_BUS_MAX]; /* VTDBus objects indexed by bus number */
> +    /* list of registered notifiers */
> +    QLIST_HEAD(, IntelIOMMUNotifierNode) notifiers_list;
>  
>      /* interrupt remapping */
>      bool intr_enabled;              /* Whether guest enabled IR */
> -- 
> 2.7.4