Re: [Qemu-devel] [PATCH v4 RESEND 3/3] IOMMU: enable intel_iommu map and unmap notifiers

[Peter Xu]

On Mon, Oct 17, 2016 at 06:44:24PM +0300, Aviv B.D wrote:
> From: "Aviv Ben-David" <address@hidden>
> 
> Adds a list of registered vtd_as's to intel iommu state to save
> iteration over each PCI device in a search of the corrosponding domain.
> 
> Signed-off-by: Aviv Ben-David <address@hidden>
> ---
>  hw/i386/intel_iommu.c          | 102 
> ++++++++++++++++++++++++++++++++++++++---
>  hw/i386/intel_iommu_internal.h |   2 +
>  include/hw/i386/intel_iommu.h  |   9 ++++
>  3 files changed, 106 insertions(+), 7 deletions(-)
> 
> diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
> index dcf45f0..34fc1e8 100644
> --- a/hw/i386/intel_iommu.c
> +++ b/hw/i386/intel_iommu.c
> @@ -51,6 +51,9 @@ static int vtd_dbgflags = VTD_DBGBIT(GENERAL) | 
> VTD_DBGBIT(CSR);
>  #define VTD_DPRINTF(what, fmt, ...) do {} while (0)
>  #endif
>  
> +static int vtd_dev_to_context_entry(IntelIOMMUState *s, uint8_t bus_num,
> +                                    uint8_t devfn, VTDContextEntry *ce);
> +
>  static void vtd_define_quad(IntelIOMMUState *s, hwaddr addr, uint64_t val,
>                              uint64_t wmask, uint64_t w1cmask)
>  {
> @@ -142,6 +145,23 @@ static uint64_t vtd_set_clear_mask_quad(IntelIOMMUState 
> *s, hwaddr addr,
>      return new_val;
>  }
>  
> +static int vtd_get_did_dev(IntelIOMMUState *s, uint8_t bus_num, uint8_t 
> devfn,
> +                           uint16_t *domain_id)
> +{
> +    VTDContextEntry ce;
> +    int ret_fr;
> +
> +    assert(domain_id);
> +
> +    ret_fr = vtd_dev_to_context_entry(s, bus_num, devfn, &ce);
> +    if (ret_fr) {
> +        return -1;
> +    }
> +
> +    *domain_id =  VTD_CONTEXT_ENTRY_DID(ce.hi);
                    ^ one more space

> +    return 0;
> +}
> +
>  /* GHashTable functions */
>  static gboolean vtd_uint64_equal(gconstpointer v1, gconstpointer v2)
>  {
> @@ -683,9 +703,6 @@ static int vtd_gpa_to_slpte(VTDContextEntry *ce, uint64_t 
> gpa,
>          *reads = (*reads) && (slpte & VTD_SL_R);
>          *writes = (*writes) && (slpte & VTD_SL_W);
>          if (!(slpte & access_right_check)) {
> -            VTD_DPRINTF(GENERAL, "error: lack of %s permission for "
> -                        "gpa 0x%"PRIx64 " slpte 0x%"PRIx64,
> -                        (flags == IOMMU_WO ? "write" : "read"), gpa, slpte);

Could I ask why we are removing these lines? It can be useful if we
have permission issues.

>              return (flags == IOMMU_RW || flags == IOMMU_WO) ?
>                     -VTD_FR_WRITE : -VTD_FR_READ;
>          }
> @@ -734,9 +751,6 @@ static int vtd_dev_to_context_entry(IntelIOMMUState *s, 
> uint8_t bus_num,
>      }
>  
>      if (!vtd_context_entry_present(ce)) {
> -        VTD_DPRINTF(GENERAL,
> -                    "error: context-entry #%"PRIu8 "(bus #%"PRIu8 ") "
> -                    "is not present", devfn, bus_num);

Here as well. Any reason to remove it?

>          return -VTD_FR_CONTEXT_ENTRY_P;
>      } else if ((ce->hi & VTD_CONTEXT_ENTRY_RSVD_HI) ||
>                 (ce->lo & VTD_CONTEXT_ENTRY_RSVD_LO)) {
> @@ -1065,6 +1079,55 @@ static void 
> vtd_iotlb_domain_invalidate(IntelIOMMUState *s, uint16_t domain_id)
>                                  &domain_id);
>  }
>  
> +static void vtd_iotlb_page_invalidate_notify(IntelIOMMUState *s,
> +                                           uint16_t domain_id, hwaddr addr,
> +                                           uint8_t am)
> +{

The logic of this function looks strange to me.

> +    IntelIOMMUNotifierNode *node;
> +
> +    QLIST_FOREACH(node, &(s->notifiers_list), next) {
> +        VTDAddressSpace *vtd_as = node->vtd_as;
> +        uint16_t vfio_domain_id;
> +        int ret = vtd_get_did_dev(s, pci_bus_num(vtd_as->bus), vtd_as->devfn,
> +                                  &vfio_domain_id);
> +        if (!ret && domain_id == vfio_domain_id) {
> +            IOMMUTLBEntry entry;
> +
> +            /* notify unmap */
> +            if (node->notifier_flag & IOMMU_NOTIFIER_UNMAP) {

First of all, if we are talking about VFIO, notifier_flag should
always be MAP|UNMAP. So in that case, for newly mapped entries, looks
like we will first send an UNMAP, then a MAP?

> +                VTD_DPRINTF(GENERAL, "Remove addr 0x%"PRIx64 " mask %d",
> +                            addr, am);
> +                entry.target_as = &address_space_memory;
> +                entry.iova = addr & VTD_PAGE_MASK_4K;
> +                entry.translated_addr = 0;
> +                entry.addr_mask = ~VTD_PAGE_MASK(VTD_PAGE_SHIFT_4K + am);
> +                entry.perm = IOMMU_NONE;
> +                memory_region_notify_iommu(&node->vtd_as->iommu, entry);
> +            }
> +
> +            /* notify map */
> +            if (node->notifier_flag & IOMMU_NOTIFIER_MAP) {
> +                hwaddr original_addr = addr;
> +                VTD_DPRINTF(GENERAL, "add addr 0x%"PRIx64 " mask %d", addr, 
> am);
> +                while (addr < original_addr + (1 << am) * VTD_PAGE_SIZE) {
> +                    /* call to vtd_iommu_translate */
> +                    IOMMUTLBEntry entry = s->iommu_ops.translate(
> +                                                         
> &node->vtd_as->iommu,
> +                                                         addr,
> +                                                         IOMMU_NO_FAIL);
> +                    if (entry.perm != IOMMU_NONE) {
> +                        addr += entry.addr_mask + 1;
> +                        memory_region_notify_iommu(&node->vtd_as->iommu, 
> entry);
> +                    } else {
> +                        addr += VTD_PAGE_SIZE;

IIUC, here is the point that we found "the page is gone" (so this is
an UNMAP invalidation), and we should do memory_region_iommu_notify()
for the whole area with IOMMU_NONE. Then we just quit the loop since
continuous translate()s should fail as well if the first page is
missing.

Please correct if I am wrong.

Thanks,

-- peterx