For fd-based shared memory, MAP_NORESERVE is only effective for hugetlb,
otherwise it's ignored. Older Linux versions that didn't support
reservation of huge pages ignored MAP_NORESERVE completely.
The first client to mmap a hugetlb fd without MAP_NORESERVE will
trigger reservation of huge pages for the whole mmapped range. There are
two cases to consider:
1) QEMU mapped RAM without MAP_NORESERVE
We're not dealing with a sparse mapping, huge pages for the whole range
have already been reserved by QEMU. An additional mmap() without
MAP_NORESERVE won't have any effect on the reservation.
2) QEMU mapped RAM with MAP_NORESERVE
We're delaing with a sparse mapping, no huge pages should be reserved.
Further mappings without MAP_NORESERVE should be avoided.
For 1), it doesn't matter if we set MAP_NORESERVE or not, so we can
simply set it. For 2), we'd be overriding QEMUs decision and trigger
reservation of huge pages, which might just fail if there are not
sufficient huge pages around. We must map with MAP_NORESERVE.
This change is required to support virtio-mem with hugetlb: a
virtio-mem device mapped into the guest physical memory corresponds to
a sparse memory mapping and QEMU maps this memory with MAP_NORESERVE.
Whenever memory in that sparse region will be accessed by the VM, QEMU
populates huge pages for the affected range by preallocating memory
and handling any preallocation errors gracefully.
So let's map shared RAM with MAP_NORESERVE. As libvhost-user only
supports Linux, there shouldn't be anything to take care of in regard of
other OS support.
Without this change, libvhost-user will fail mapping the region if there
are currently not enough huge pages to perform the reservation:
fv_panic: libvhost-user: region mmap error: Cannot allocate memory
Cc: "Marc-André Lureau" <marcandre.lureau@redhat.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Raphael Norwitz <raphael.norwitz@nutanix.com>
Cc: Stefan Hajnoczi <stefanha@redhat.com>
Cc: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20220111123939.132659-1-david@redhat.com>
Acked-by: Raphael Norwitz <raphael.norwitz@nutanix.com>
Today if QEMU (or any other VMM) has sent multiple copies of the same
region to a libvhost-user based backend and then attempts to remove the
region, only one instance of the region will be removed, leaving stale
copies of the region in dev->regions[].
This change resolves this by having vu_rem_mem_reg() iterate through all
regions in dev->regions[] and delete all matching regions.
Suggested-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Raphael Norwitz <raphael.norwitz@nutanix.com>
Message-Id: <20220117041050.19718-7-raphael.norwitz@nutanix.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
When VHOST_USER_PROTOCOL_F_CONFIGURE_MEM_SLOTS support was added to
libvhost-user, no guardrails were added to protect against QEMU
attempting to hot-add too many RAM slots to a VM with a libvhost-user
based backed attached.
This change adds the missing error handling by introducing a check on
the number of RAM slots the device has available before proceeding to
process the VHOST_USER_ADD_MEM_REG message.
Suggested-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Raphael Norwitz <raphael.norwitz@nutanix.com>
Message-Id: <20220117041050.19718-6-raphael.norwitz@nutanix.com>
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: Philippe Mathieu-Daudé <f4bug@amsat.org>
We end up not closing the file descriptor, resulting in leaking one
file descriptor for each VHOST_USER_REM_MEM_REG message.
Fixes: 875b9fd97b ("Support individual region unmap in libvhost-user")
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Raphael Norwitz <raphael.norwitz@nutanix.com>
Cc: "Marc-André Lureau" <marcandre.lureau@redhat.com>
Cc: Stefan Hajnoczi <stefanha@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Coiby Xu <coiby.xu@gmail.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Raphael Norwitz <raphael.norwitz@nutanix.com>
Message-Id: <20220117041050.19718-5-raphael.norwitz@nutanix.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Let's avoid having to manually copy all elements. Copy only the ones
necessary to close the hole and perform the operation in-place without
a second array.
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Raphael Norwitz <raphael.norwitz@nutanix.com>
Message-Id: <20220117041050.19718-4-raphael.norwitz@nutanix.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Today if multiple FDs are sent from the VMM to the backend in a
VHOST_USER_ADD_MEM_REG message, one FD will be mapped and the remaining
FDs will be leaked. Therefore if multiple FDs are sent we report an
error and fail the operation, closing all FDs in the message.
Likewise in case the VMM sends a message with a size less than that
of a memory region descriptor, we add a check to gracefully report an
error and fail the operation rather than crashing.
Signed-off-by: Raphael Norwitz <raphael.norwitz@nutanix.com>
Message-Id: <20220117041050.19718-3-raphael.norwitz@nutanix.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Today if multiple FDs are sent from the VMM to the backend in a
VHOST_USER_REM_MEM_REG message, one FD will be unmapped and the remaining
FDs will be leaked. Therefore if multiple FDs are sent we report an
error and fail the operation, closing all FDs in the message.
Likewise in case the VMM sends a message with a size less than that of a
memory region descriptor, we add a check to gracefully report an error
and fail the operation rather than crashing.
Signed-off-by: Raphael Norwitz <raphael.norwitz@nutanix.com>
Message-Id: <20220117041050.19718-2-raphael.norwitz@nutanix.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
We end up not copying the mmap_addr of all existing regions, resulting
in a SEGFAULT once we actually try to map/access anything within our
memory regions.
Fixes: 875b9fd97b ("Support individual region unmap in libvhost-user")
Cc: qemu-stable@nongnu.org
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Raphael Norwitz <raphael.norwitz@nutanix.com>
Cc: "Marc-André Lureau" <marcandre.lureau@redhat.com>
Cc: Stefan Hajnoczi <stefanha@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Coiby Xu <coiby.xu@gmail.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20211011201047.62587-1-david@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Raphael Norwitz <raphael.norwitz@nutanix.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
../subprojects/libvhost-user/libvhost-user.c:1070:12: error: format ‘%lx’ expects argument of type ‘long unsigned int’, but argument 3 has type ‘__u64’ {aka ‘long long unsigned int’} [-Werror=format=]
1070 | DPRINT(" desc_user_addr: 0x%016" PRIx64 "\n", vra->desc_user_addr);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~
| |
| __u64 {aka long long unsigned int}
Rather than using %llx, which may fail if __u64 is declared differently
elsewhere, let's just cast the values. Feel free to propose a better solution!
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20210505151313.203258-2-marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Meson now checks that subprojects do not access files from parent
project. While we all agree this is best practice, libvhost-user also
want to share a few headers with QEMU, and libvhost-user isn't really a
standalone project at this point (although this is making the dependency
a bit more explicit).
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20210505151313.203258-1-marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This help fixing static compilation issues.
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20210114125605.1227742-4-marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Musl libc complains about it's wrong usage.
In file included from ../subprojects/libvhost-user/libvhost-user.h:20,
from ../subprojects/libvhost-user/libvhost-user-glib.h:19,
from ../subprojects/libvhost-user/libvhost-user-glib.c:15:
/usr/include/sys/poll.h:1:2: error: #warning redirecting incorrect #include <sys/poll.h> to <poll.h> [-Werror=cpp]
1 | #warning redirecting incorrect #include <sys/poll.h> to <poll.h>
| ^~~~~~~
Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20210118063808.12471-3-jiaxun.yang@flygoat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20201125100640.366523-8-marcandre.lureau@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
By making libvhost-user a subproject, check it builds
standalone (without the global QEMU cflags etc).
Note that the library still relies on QEMU include/qemu/atomic.h and
linux_headers/.
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20201125100640.366523-6-marcandre.lureau@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
