Following the example documented since commit e3fe3988d7
("error: Document Error API usage rules"), have
memory_region_init_rom_device_nomigrate() return a boolean
indicating whether an error is set or not.
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Message-Id: <20231120213301.24349-9-philmd@linaro.org>
Type names should not contain special characters like ":". Let's
remove the whole prefix here since it does not really seem to be
helpful to have such a prefix here. The type name is only used
internally for an interface type, so the renaming should not affect
the user interface or migration.
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20231117114457.177308-4-thuth@redhat.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
This helper will allow to convey information about valid
IOVA ranges to virtual IOMMUS.
Signed-off-by: Eric Auger <eric.auger@redhat.com>
Acked-by: Peter Xu <peterx@redhat.com>
Reviewed-by: "Michael S. Tsirkin" <mst@redhat.com>
[ clg: fixes in memory_region_iommu_set_iova_ranges() and
iommu_set_iova_ranges() documentation ]
Signed-off-by: Cédric Le Goater <clg@redhat.com>
A reserved region is a range tagged with a type. Let's directly use
the Range type in the prospect to reuse some of the library helpers
shipped with the Range type.
Signed-off-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Reviewed-by: "Michael S. Tsirkin" <mst@redhat.com>
Signed-off-by: Cédric Le Goater <clg@redhat.com>
Coverity scan reports multiple false-positive "defects" for the
following series of actions in virtio.c:
MemoryRegionCache indirect_desc_cache;
address_space_cache_init_empty(&indirect_desc_cache);
address_space_cache_destroy(&indirect_desc_cache);
For some reason it's unable to recognize the dependency between 'mrs.mr'
and 'fv' and insists that '!mrs.mr' check in address_space_cache_destroy
may take a 'false' branch, even though it is explicitly initialized to
NULL in the address_space_cache_init_empty():
*** CID 1522371: Memory - illegal accesses (UNINIT)
/qemu/hw/virtio/virtio.c: 1627 in virtqueue_split_pop()
1621 }
1622
1623 vq->inuse++;
1624
1625 trace_virtqueue_pop(vq, elem, elem->in_num, elem->out_num);
1626 done:
>>> CID 1522371: Memory - illegal accesses (UNINIT)
>>> Using uninitialized value "indirect_desc_cache.fv" when
>>> calling "address_space_cache_destroy".
1627 address_space_cache_destroy(&indirect_desc_cache);
1628
1629 return elem;
1630
1631 err_undo_map:
1632 virtqueue_undo_map_desc(out_num, in_num, iov);
** CID 1522370: Memory - illegal accesses (UNINIT)
Instead of trying to silence these false positive reports in 4
different places, initializing 'fv' as well, as this doesn't result
in any noticeable performance impact.
Signed-off-by: Ilya Maximets <i.maximets@ovn.org>
Message-Id: <20231009104322.3085887-1-i.maximets@ovn.org>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Let's allow for marking memory regions unmergeable, to teach
flatview code and vhost to not merge adjacent aliases to the same memory
region into a larger memory section; instead, we want separate aliases to
stay separate such that we can atomically map/unmap aliases without
affecting other aliases.
This is desired for virtio-mem mapping device memory located on a RAM
memory region via multiple aliases into a memory region container,
resulting in separate memslots that can get (un)mapped atomically.
As an example with virtio-mem, the layout would look something like this:
[...]
0000000240000000-00000020bfffffff (prio 0, i/o): device-memory
0000000240000000-000000043fffffff (prio 0, i/o): virtio-mem
0000000240000000-000000027fffffff (prio 0, ram): alias memslot-0 @mem2 0000000000000000-000000003fffffff
0000000280000000-00000002bfffffff (prio 0, ram): alias memslot-1 @mem2 0000000040000000-000000007fffffff
00000002c0000000-00000002ffffffff (prio 0, ram): alias memslot-2 @mem2 0000000080000000-00000000bfffffff
[...]
Without unmergable memory regions, all three memslots would get merged into
a single memory section. For example, when mapping another alias (e.g.,
virtio-mem-memslot-3) or when unmapping any of the mapped aliases,
memory listeners will first get notified about the removal of the big
memory section to then get notified about re-adding of the new
(differently merged) memory section(s).
In an ideal world, memory listeners would be able to deal with that
atomically, like KVM nowadays does. However, (a) supporting this for other
memory listeners (vhost-user, vfio) is fairly hard: temporary removal
can result in all kinds of issues on concurrent access to guest memory;
and (b) this handling is undesired, because temporarily removing+readding
can consume quite some time on bigger memslots and is not efficient
(e.g., vfio unpinning and repinning pages ...).
Let's allow for marking a memory region unmergeable, such that we
can atomically (un)map aliases to the same memory region, similar to
(un)mapping individual DIMMs.
Similarly, teach vhost code to not redo what flatview core stopped doing:
don't merge such sections. Merging in vhost code is really only relevant
for handling random holes in boot memory where; without this merging,
the vhost-user backend wouldn't be able to mmap() some boot memory
backed on hugetlb.
We'll use this for virtio-mem next.
Message-ID: <20230926185738.277351-18-david@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
We really only care about the RAM memory region not being mapped into
an address space yet as long as we're still setting up the
RamDiscardManager. Once mapped into an address space, memory notifiers
would get notified about such a region and any attempts to modify the
RamDiscardManager would be wrong.
While "mapped into an address space" is easy to check for RAM regions that
are mapped directly (following the ->container links), it's harder to
check when such regions are mapped indirectly via aliases. For now, we can
only detect that a region is mapped through an alias (->mapped_via_alias),
but we don't have a handle on these aliases to follow all their ->container
links to test if they are eventually mapped into an address space.
So relax the assertion in memory_region_set_ram_discard_manager(),
remove the check in memory_region_get_ram_discard_manager() and clarify
the doc.
Message-ID: <20230926185738.277351-14-david@redhat.com>
Reviewed-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Lots of virtio functions that are on a hot path in data transmission
are initializing indirect descriptor cache at the point of stack
allocation. It's a 112 byte structure that is getting zeroed out on
each call adding unnecessary overhead. It's going to be correctly
initialized later via special init function. The only reason to
actually initialize right away is the ability to safely destruct it.
Replacing a designated initializer with a function to only initialize
what is necessary.
Removal of the unnecessary stack initializations improves throughput
of virtio-net devices in terms of 64B packets per second by 6-14 %
depending on the case. Tested with a proposed af-xdp network backend
and a dpdk testpmd application in the guest, but should be beneficial
for other virtio devices as well.
Signed-off-by: Ilya Maximets <i.maximets@ovn.org>
Message-Id: <20230811143423.3258788-1-i.maximets@ovn.org>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
When updating ioeventfds, we need to iterate all address spaces,
but some address spaces do not register eventfd_add|del call when
memory_listener_register() and they do nothing when updating ioeventfds.
So we can skip these AS in address_space_update_ioeventfds().
The overhead of memory_region_transaction_commit() can be significantly
reduced. For example, a VM with 8 vhost net devices and each one has
64 vectors, can reduce the time spent on memory_region_transaction_commit by 20%.
Message-ID: <20230830032906.12488-1-hongmianquan@bytedance.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: hongmianquan <hongmianquan@bytedance.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
There is a difference between how we open a file and how we mmap it,
and we want to support writable private mappings of readonly files. Let's
define RAM_READONLY and RAM_READONLY_FD flags, to replace the single
"readonly" parameter for file-related functions.
In memory_region_init_ram_from_fd() and memory_region_init_ram_from_file(),
initialize mr->readonly based on the new RAM_READONLY flag.
While at it, add some RAM_* flags we missed to add to the list of accepted
flags in the documentation of some functions.
No change in functionality intended. We'll make use of both flags next
and start setting them independently for memory-backend-file.
Message-ID: <20230906120503.359863-3-david@redhat.com>
Acked-by: Peter Xu <peterx@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
