Re: [PATCH v2] vhost: fix madvise arguments alignment

[Patrick Robb <probb@iol.unh.edu>]

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UNH CI reported an ABI failure for this patch which did not report due to a
bug on our end, so I'm manually reporting it now. I see Maxime you already
predicted the issue though!

*07:58:32*  1 function with some indirect sub-type change:*07:58:32*
*07:58:32*    [C] 'function int rte_vhost_get_mem_table(int,
rte_vhost_memory**)' at vhost.c:922:1 has some indirect sub-type
changes:*07:58:32*      parameter 2 of type 'rte_vhost_memory**' has
sub-type changes:*07:58:32*        in pointed to type
'rte_vhost_memory*':*07:58:32*          in pointed to type 'struct
rte_vhost_memory' at rte_vhost.h:145:1:*07:58:32*            type size
hasn't changed*07:58:32*            1 data member change:*07:58:32*
          type of 'rte_vhost_mem_region regions[]' changed:*07:58:32*
              array element type 'struct rte_vhost_mem_region'
changed:*07:58:32*                  type size changed from 448 to 512
(in bits)*07:58:32*                  1 data member
insertion:*07:58:32*                    'uint64_t alignment', at
offset 448 (in bits) at rte_vhost.h:139:1*07:58:32*
type size hasn't changed*07:58:32*  *07:58:32*  Error: ABI issue
reported for abidiff --suppr dpdk/devtools/libabigail.abignore
--no-added-syms --headers-dir1 reference/include --headers-dir2
build_install/include reference/dump/librte_vhost.dump
build_install/dump/librte_vhost.dump*07:58:32*  ABIDIFF_ABI_CHANGE,
this change requires a review (abidiff flagged this as a potential
issue).


On Thu, Feb 23, 2023 at 11:57 AM Mike Pattrick <mkp@redhat.com> wrote:

> On Thu, Feb 23, 2023 at 11:12 AM Maxime Coquelin
> <maxime.coquelin@redhat.com> wrote:
> >
> > Hi Mike,
> >
> > Thanks for  looking into this issue.
> >
> > On 2/23/23 05:35, Mike Pattrick wrote:
> > > The arguments passed to madvise should be aligned to the alignment of
> > > the backing memory. Now we keep track of each regions alignment and use
> > > then when setting coredump preferences. To facilitate this, a new
> member
> > > was added to rte_vhost_mem_region. A new function was added to easily
> > > translate memory address back to region alignment. Unneeded calls to
> > > madvise were reduced, as the cache removal case should already be
> > > covered by the cache insertion case. The previously inline function
> > > mem_set_dump was removed from a header file and made not inline.
> > >
> > > Fixes: 338ad77c9ed3 ("vhost: exclude VM hugepages from coredumps")
> > >
> > > Signed-off-by: Mike Pattrick <mkp@redhat.com>
> > > ---
> > > Since v1:
> > >   - Corrected a cast for 32bit compiles
> > > ---
> > >   lib/vhost/iotlb.c      |  9 +++---
> > >   lib/vhost/rte_vhost.h  |  1 +
> > >   lib/vhost/vhost.h      | 12 ++------
> > >   lib/vhost/vhost_user.c | 63
> +++++++++++++++++++++++++++++++++++-------
> > >   4 files changed, 60 insertions(+), 25 deletions(-)
> > >
> > > diff --git a/lib/vhost/iotlb.c b/lib/vhost/iotlb.c
> > > index a0b8fd7302..5293507b63 100644
> > > --- a/lib/vhost/iotlb.c
> > > +++ b/lib/vhost/iotlb.c
> > > @@ -149,7 +149,6 @@ vhost_user_iotlb_cache_remove_all(struct
> vhost_virtqueue *vq)
> > >       rte_rwlock_write_lock(&vq->iotlb_lock);
> > >
> > >       RTE_TAILQ_FOREACH_SAFE(node, &vq->iotlb_list, next, temp_node) {
> > > -             mem_set_dump((void *)(uintptr_t)node->uaddr, node->size,
> true);
> >
> > Hmm, it should have been called with enable=false here since we are
> > removing the entry from the IOTLB cache. It should be kept in order to
> > "DONTDUMP" pages evicted from the cache.
>
> Here I was thinking that if we add an entry and then remove a
> different entry, they could be in the same page. But on I should have
> kept an enable=false in remove_all().
>
> And now that I think about it again, I could just check if there are
> any active cache entries in the page on every evict/remove, they're
> sorted so that should be an easy check. Unless there are any
> objections I'll go forward with that.
>
> >
> > >               TAILQ_REMOVE(&vq->iotlb_list, node, next);
> > >               vhost_user_iotlb_pool_put(vq, node);
> > >       }
> > > @@ -171,7 +170,6 @@ vhost_user_iotlb_cache_random_evict(struct
> vhost_virtqueue *vq)
> > >
> > >       RTE_TAILQ_FOREACH_SAFE(node, &vq->iotlb_list, next, temp_node) {
> > >               if (!entry_idx) {
> > > -                     mem_set_dump((void *)(uintptr_t)node->uaddr,
> node->size, true);
> >
> > Same here.
> >
> > >                       TAILQ_REMOVE(&vq->iotlb_list, node, next);
> > >                       vhost_user_iotlb_pool_put(vq, node);
> > >                       vq->iotlb_cache_nr--;
> > > @@ -224,14 +222,16 @@ vhost_user_iotlb_cache_insert(struct virtio_net
> *dev, struct vhost_virtqueue *vq
> > >                       vhost_user_iotlb_pool_put(vq, new_node);
> > >                       goto unlock;
> > >               } else if (node->iova > new_node->iova) {
> > > -                     mem_set_dump((void *)(uintptr_t)node->uaddr,
> node->size, true);
> > > +                     mem_set_dump((void *)(uintptr_t)new_node->uaddr,
> new_node->size, true,
> > > +                             hua_to_alignment(dev->mem, (void
> *)(uintptr_t)node->uaddr));
> > >                       TAILQ_INSERT_BEFORE(node, new_node, next);
> > >                       vq->iotlb_cache_nr++;
> > >                       goto unlock;
> > >               }
> > >       }
> > >
> > > -     mem_set_dump((void *)(uintptr_t)node->uaddr, node->size, true);
> > > +     mem_set_dump((void *)(uintptr_t)new_node->uaddr, new_node->size,
> true,
> > > +             hua_to_alignment(dev->mem, (void
> *)(uintptr_t)new_node->uaddr));
> > >       TAILQ_INSERT_TAIL(&vq->iotlb_list, new_node, next);
> > >       vq->iotlb_cache_nr++;
> > >
> > > @@ -259,7 +259,6 @@ vhost_user_iotlb_cache_remove(struct
> vhost_virtqueue *vq,
> > >                       break;
> > >
> > >               if (iova < node->iova + node->size) {
> > > -                     mem_set_dump((void *)(uintptr_t)node->uaddr,
> node->size, true);
> > >                       TAILQ_REMOVE(&vq->iotlb_list, node, next);
> > >                       vhost_user_iotlb_pool_put(vq, node);
> > >                       vq->iotlb_cache_nr--;
> > > diff --git a/lib/vhost/rte_vhost.h b/lib/vhost/rte_vhost.h
> > > index a395843fe9..c5c97ea67e 100644
> > > --- a/lib/vhost/rte_vhost.h
> > > +++ b/lib/vhost/rte_vhost.h
> > > @@ -136,6 +136,7 @@ struct rte_vhost_mem_region {
> > >       void     *mmap_addr;
> > >       uint64_t mmap_size;
> > >       int fd;
> > > +     uint64_t alignment;
> >
> > This is not possible to do this as it breaks the ABI.
> > You have to store the information somewhere else, or simply call
> > get_blk_size() in hua_to_alignment() since the fd is not closed.
> >
>
> Sorry about that! You're right, checking the fd per operation should
> be easy enough.
>
> Thanks for the review,
>
> M
>
> > >   };
> > >
> > >   /**
> > > diff --git a/lib/vhost/vhost.h b/lib/vhost/vhost.h
> > > index 5750f0c005..a2467ba509 100644
> > > --- a/lib/vhost/vhost.h
> > > +++ b/lib/vhost/vhost.h
> > > @@ -1009,14 +1009,6 @@ mbuf_is_consumed(struct rte_mbuf *m)
> > >       return true;
> > >   }
> > >
> > > -static __rte_always_inline void
> > > -mem_set_dump(__rte_unused void *ptr, __rte_unused size_t size,
> __rte_unused bool enable)
> > > -{
> > > -#ifdef MADV_DONTDUMP
> > > -     if (madvise(ptr, size, enable ? MADV_DODUMP : MADV_DONTDUMP) ==
> -1) {
> > > -             rte_log(RTE_LOG_INFO, vhost_config_log_level,
> > > -                     "VHOST_CONFIG: could not set coredump preference
> (%s).\n", strerror(errno));
> > > -     }
> > > -#endif
> > > -}
> > > +uint64_t hua_to_alignment(struct rte_vhost_memory *mem, void *ptr);
> > > +void mem_set_dump(void *ptr, size_t size, bool enable, uint64_t
> alignment);
> > >   #endif /* _VHOST_NET_CDEV_H_ */
> > > diff --git a/lib/vhost/vhost_user.c b/lib/vhost/vhost_user.c
> > > index d702d082dd..6d09597fbe 100644
> > > --- a/lib/vhost/vhost_user.c
> > > +++ b/lib/vhost/vhost_user.c
> > > @@ -737,6 +737,40 @@ log_addr_to_gpa(struct virtio_net *dev, struct
> vhost_virtqueue *vq)
> > >       return log_gpa;
> > >   }
> > >
> > > +uint64_t
> > > +hua_to_alignment(struct rte_vhost_memory *mem, void *ptr)
> > > +{
> > > +     struct rte_vhost_mem_region *r;
> > > +     uint32_t i;
> > > +     uintptr_t hua = (uintptr_t)ptr;
> > > +
> > > +     for (i = 0; i < mem->nregions; i++) {
> > > +             r = &mem->regions[i];
> > > +             if (hua >= r->host_user_addr &&
> > > +                     hua < r->host_user_addr + r->size) {
> > > +                     return r->alignment;
> > > +             }
> > > +     }
> > > +
> > > +     /* If region isn't found, don't align at all */
> > > +     return 1;
> > > +}
> > > +
> > > +void
> > > +mem_set_dump(void *ptr, size_t size, bool enable, uint64_t pagesz)
> > > +{
> > > +#ifdef MADV_DONTDUMP
> > > +     void *start = RTE_PTR_ALIGN_FLOOR(ptr, pagesz);
> > > +     uintptr_t end = RTE_ALIGN_CEIL((uintptr_t)ptr + size, pagesz);
> > > +     size_t len = end - (uintptr_t)start;
> > > +
> > > +     if (madvise(start, len, enable ? MADV_DODUMP : MADV_DONTDUMP) ==
> -1) {
> > > +             rte_log(RTE_LOG_INFO, vhost_config_log_level,
> > > +                     "VHOST_CONFIG: could not set coredump preference
> (%s).\n", strerror(errno));
> > > +     }
> > > +#endif
> > > +}
> > > +
> > >   static void
> > >   translate_ring_addresses(struct virtio_net **pdev, struct
> vhost_virtqueue **pvq)
> > >   {
> > > @@ -767,6 +801,8 @@ translate_ring_addresses(struct virtio_net **pdev,
> struct vhost_virtqueue **pvq)
> > >                       return;
> > >               }
> > >
> > > +             mem_set_dump(vq->desc_packed, len, true,
> > > +                     hua_to_alignment(dev->mem, vq->desc_packed));
> > >               numa_realloc(&dev, &vq);
> > >               *pdev = dev;
> > >               *pvq = vq;
> > > @@ -782,6 +818,8 @@ translate_ring_addresses(struct virtio_net **pdev,
> struct vhost_virtqueue **pvq)
> > >                       return;
> > >               }
> > >
> > > +             mem_set_dump(vq->driver_event, len, true,
> > > +                     hua_to_alignment(dev->mem, vq->driver_event));
> > >               len = sizeof(struct vring_packed_desc_event);
> > >               vq->device_event = (struct vring_packed_desc_event *)
> > >                                       (uintptr_t)ring_addr_to_vva(dev,
> > > @@ -793,9 +831,8 @@ translate_ring_addresses(struct virtio_net **pdev,
> struct vhost_virtqueue **pvq)
> > >                       return;
> > >               }
> > >
> > > -             mem_set_dump(vq->desc_packed, len, true);
> > > -             mem_set_dump(vq->driver_event, len, true);
> > > -             mem_set_dump(vq->device_event, len, true);
> > > +             mem_set_dump(vq->device_event, len, true,
> > > +                     hua_to_alignment(dev->mem, vq->device_event));
> > >               vq->access_ok = true;
> > >               return;
> > >       }
> > > @@ -812,6 +849,7 @@ translate_ring_addresses(struct virtio_net **pdev,
> struct vhost_virtqueue **pvq)
> > >               return;
> > >       }
> > >
> > > +     mem_set_dump(vq->desc, len, true, hua_to_alignment(dev->mem,
> vq->desc));
> > >       numa_realloc(&dev, &vq);
> > >       *pdev = dev;
> > >       *pvq = vq;
> > > @@ -827,6 +865,7 @@ translate_ring_addresses(struct virtio_net **pdev,
> struct vhost_virtqueue **pvq)
> > >               return;
> > >       }
> > >
> > > +     mem_set_dump(vq->avail, len, true, hua_to_alignment(dev->mem,
> vq->avail));
> > >       len = sizeof(struct vring_used) +
> > >               sizeof(struct vring_used_elem) * vq->size;
> > >       if (dev->features & (1ULL << VIRTIO_RING_F_EVENT_IDX))
> > > @@ -839,6 +878,8 @@ translate_ring_addresses(struct virtio_net **pdev,
> struct vhost_virtqueue **pvq)
> > >               return;
> > >       }
> > >
> > > +     mem_set_dump(vq->used, len, true, hua_to_alignment(dev->mem,
> vq->used));
> > > +
> > >       if (vq->last_used_idx != vq->used->idx) {
> > >               VHOST_LOG_CONFIG(dev->ifname, WARNING,
> > >                       "last_used_idx (%u) and vq->used->idx (%u)
> mismatches;\n",
> > > @@ -849,9 +890,6 @@ translate_ring_addresses(struct virtio_net **pdev,
> struct vhost_virtqueue **pvq)
> > >                       "some packets maybe resent for Tx and dropped
> for Rx\n");
> > >       }
> > >
> > > -     mem_set_dump(vq->desc, len, true);
> > > -     mem_set_dump(vq->avail, len, true);
> > > -     mem_set_dump(vq->used, len, true);
> > >       vq->access_ok = true;
> > >
> > >       VHOST_LOG_CONFIG(dev->ifname, DEBUG, "mapped address desc:
> %p\n", vq->desc);
> > > @@ -1230,7 +1268,8 @@ vhost_user_mmap_region(struct virtio_net *dev,
> > >       region->mmap_addr = mmap_addr;
> > >       region->mmap_size = mmap_size;
> > >       region->host_user_addr = (uint64_t)(uintptr_t)mmap_addr +
> mmap_offset;
> > > -     mem_set_dump(mmap_addr, mmap_size, false);
> > > +     region->alignment = alignment;
> > > +     mem_set_dump(mmap_addr, mmap_size, false, alignment);
> > >
> > >       if (dev->async_copy) {
> > >               if (add_guest_pages(dev, region, alignment) < 0) {
> > > @@ -1535,7 +1574,6 @@ inflight_mem_alloc(struct virtio_net *dev, const
> char *name, size_t size, int *f
> > >               return NULL;
> > >       }
> > >
> > > -     mem_set_dump(ptr, size, false);
> > >       *fd = mfd;
> > >       return ptr;
> > >   }
> > > @@ -1566,6 +1604,7 @@ vhost_user_get_inflight_fd(struct virtio_net
> **pdev,
> > >       uint64_t pervq_inflight_size, mmap_size;
> > >       uint16_t num_queues, queue_size;
> > >       struct virtio_net *dev = *pdev;
> > > +     uint64_t alignment;
> > >       int fd, i, j;
> > >       int numa_node = SOCKET_ID_ANY;
> > >       void *addr;
> > > @@ -1628,6 +1667,8 @@ vhost_user_get_inflight_fd(struct virtio_net
> **pdev,
> > >               dev->inflight_info->fd = -1;
> > >       }
> > >
> > > +     alignment = get_blk_size(fd);
> > > +     mem_set_dump(addr, mmap_size, false, alignment);
> > >       dev->inflight_info->addr = addr;
> > >       dev->inflight_info->size = ctx->msg.payload.inflight.mmap_size =
> mmap_size;
> > >       dev->inflight_info->fd = ctx->fds[0] = fd;
> > > @@ -1744,10 +1785,10 @@ vhost_user_set_inflight_fd(struct virtio_net
> **pdev,
> > >               dev->inflight_info->fd = -1;
> > >       }
> > >
> > > -     mem_set_dump(addr, mmap_size, false);
> > >       dev->inflight_info->fd = fd;
> > >       dev->inflight_info->addr = addr;
> > >       dev->inflight_info->size = mmap_size;
> > > +     mem_set_dump(addr, mmap_size, false, get_blk_size(fd));
> > >
> > >       for (i = 0; i < num_queues; i++) {
> > >               vq = dev->virtqueue[i];
> > > @@ -2242,6 +2283,7 @@ vhost_user_set_log_base(struct virtio_net **pdev,
> > >       struct virtio_net *dev = *pdev;
> > >       int fd = ctx->fds[0];
> > >       uint64_t size, off;
> > > +     uint64_t alignment;
> > >       void *addr;
> > >       uint32_t i;
> > >
> > > @@ -2280,6 +2322,7 @@ vhost_user_set_log_base(struct virtio_net **pdev,
> > >        * fail when offset is not page size aligned.
> > >        */
> > >       addr = mmap(0, size + off, PROT_READ | PROT_WRITE, MAP_SHARED,
> fd, 0);
> > > +     alignment = get_blk_size(fd);
> > >       close(fd);
> > >       if (addr == MAP_FAILED) {
> > >               VHOST_LOG_CONFIG(dev->ifname, ERR, "mmap log base
> failed!\n");
> > > @@ -2296,7 +2339,7 @@ vhost_user_set_log_base(struct virtio_net **pdev,
> > >       dev->log_addr = (uint64_t)(uintptr_t)addr;
> > >       dev->log_base = dev->log_addr + off;
> > >       dev->log_size = size;
> > > -     mem_set_dump(addr, size, false);
> > > +     mem_set_dump(addr, size + off, false, alignment);
> > >
> > >       for (i = 0; i < dev->nr_vring; i++) {
> > >               struct vhost_virtqueue *vq = dev->virtqueue[i];
> >
>
>

-- 

Patrick Robb

Technical Service Manager

UNH InterOperability Laboratory

21 Madbury Rd, Suite 100, Durham, NH 03824

www.iol.unh.edu

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