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

[Aviv B.D.]

I will fix all those issues.
Thanks,
Aviv.

On Thu, Oct 20, 2016 at 10:11 PM, Aviv B.D. <address@hidden> wrote:

>
>
> On Wed, Oct 19, 2016 at 12:33 PM, Peter Xu <address@hidden> wrote:
>
>> 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.
>>
>
> I will return Those lines if flags & NO_FAIL == 0
>
>>
>> >              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?
>>
>>
> Here as well...
>
>
>> >          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?
>>
>
> You are correct, there is no valid reason to have notifier_flag other than
> MAP|UNMAP
> at least for VFIO.
> I'm not sure if in the feature there won't be good reason to do otherwise,
> so my
> code support this scenario...
>
>
>> > +                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.
>>
>
> If I remember correctly I encounter a few cases where there was hole of
> unmaped
> memory in the middle of otherwise mapped pages. If I remember correctly it
> was
> with linux kernel 4.4, but I'm not sure.
>
>
>> Thanks,
>>
>> -- peterx
>>
>
>