Re: [PATCH v4 00/12] vhost-user: support any POSIX system (tested on macOS, FreeBSD, OpenBSD)

[Stefan Hajnoczi]

On Wed, May 08, 2024 at 09:44:44AM +0200, Stefano Garzarella wrote:
> v1: https://patchew.org/QEMU/20240228114759.44758-1-sgarzare@redhat.com/
> v2: https://patchew.org/QEMU/20240326133936.125332-1-sgarzare@redhat.com/
> v3: https://patchew.org/QEMU/20240404122330.92710-1-sgarzare@redhat.com/
> v4:
>   - rebased on master (commit e116b92d01c2cd75957a9f8ad1d4932292867b81)
>   - added patch 6 to move using QEMU bswap helper functions in a separate
>     patch (Phil)
>   - fail if we find "share=off" in shm_backend_memory_alloc() (David)
>   - added Phil's R-b and David's A-b
> 
> The vhost-user protocol is not really Linux-specific, so let's try support
> QEMU's frontends and backends (including libvhost-user) in any POSIX system
> with this series. The main use case is to be able to use virtio devices that
> we don't have built-in in QEMU (e.g. virtiofsd, vhost-user-vsock, etc.) even
> in non-Linux systems.
> 
> The first 5 patches are more like fixes discovered at runtime on macOS or
> FreeBSD that could go even independently of this series.
> 
> Patches 6, 7, 8, and 9 enable building of frontends and backends (including
> libvhost-user) with associated code changes to succeed in compilation.
> 
> Patch 10 adds `memory-backend-shm` that uses the POSIX shm_open() API to
> create shared memory which is identified by an fd that can be shared with
> vhost-user backends. This is useful on those systems (like macOS) where
> we don't have memfd_create() or special filesystems like "/dev/shm".
> 
> Patches 11 and 12 use `memory-backend-shm` in some vhost-user tests.
> 
> Maybe the first 5 patches can go separately, but I only discovered those
> problems after testing patches 6 - 9, so I have included them in this series
> for now. Please let me know if you prefer that I send them separately.
> 
> I tested this series using vhost-user-blk and QSD on macOS Sonoma 14.4
> (aarch64), FreeBSD 14 (x86_64), OpenBSD 7.4 (x86_64), and Fedora 39 (x86_64)
> in this way:
> 
> - Start vhost-user-blk or QSD (same commands for all systems)
> 
>   vhost-user-blk -s /tmp/vhost.socket \
>     -b Fedora-Cloud-Base-39-1.5.x86_64.raw
> 
>   qemu-storage-daemon \
>     --blockdev 
> file,filename=Fedora-Cloud-Base-39-1.5.x86_64.qcow2,node-name=file \
>     --blockdev qcow2,file=file,node-name=qcow2 \
>     --export 
> vhost-user-blk,addr.type=unix,addr.path=/tmp/vhost.socket,id=vub,num-queues=1,node-name=qcow2,writable=on
> 
> - macOS (aarch64): start QEMU (using hvf accelerator)
> 
>   qemu-system-aarch64 -smp 2 -cpu host -M virt,accel=hvf,memory-backend=mem \
>     -drive 
> file=./build/pc-bios/edk2-aarch64-code.fd,if=pflash,format=raw,readonly=on \
>     -device virtio-net-device,netdev=net0 -netdev user,id=net0 \
>     -device ramfb -device usb-ehci -device usb-kbd \
>     -object memory-backend-shm,id=mem,size=512M \
>     -device vhost-user-blk-pci,num-queues=1,disable-legacy=on,chardev=char0 \
>     -chardev socket,id=char0,path=/tmp/vhost.socket
> 
> - FreeBSD/OpenBSD (x86_64): start QEMU (no accelerators available)
> 
>   qemu-system-x86_64 -smp 2 -M q35,memory-backend=mem \
>     -object memory-backend-shm,id=mem,size="512M" \
>     -device vhost-user-blk-pci,num-queues=1,chardev=char0 \
>     -chardev socket,id=char0,path=/tmp/vhost.socket
> 
> - Fedora (x86_64): start QEMU (using kvm accelerator)
> 
>   qemu-system-x86_64 -smp 2 -M q35,accel=kvm,memory-backend=mem \
>     -object memory-backend-shm,size="512M" \
>     -device vhost-user-blk-pci,num-queues=1,chardev=char0 \
>     -chardev socket,id=char0,path=/tmp/vhost.socket
> 
> Branch pushed (and CI started) at 
> https://gitlab.com/sgarzarella/qemu/-/tree/macos-vhost-user?ref_type=heads
> 
> Thanks,
> Stefano
> 
> Stefano Garzarella (12):
>   libvhost-user: set msg.msg_control to NULL when it is empty
>   libvhost-user: fail vu_message_write() if sendmsg() is failing
>   libvhost-user: mask F_INFLIGHT_SHMFD if memfd is not supported
>   vhost-user-server: do not set memory fd non-blocking
>   contrib/vhost-user-blk: fix bind() using the right size of the address
>   contrib/vhost-user-*: use QEMU bswap helper functions
>   vhost-user: enable frontends on any POSIX system
>   libvhost-user: enable it on any POSIX system
>   contrib/vhost-user-blk: enable it on any POSIX system
>   hostmem: add a new memory backend based on POSIX shm_open()
>   tests/qtest/vhost-user-blk-test: use memory-backend-shm
>   tests/qtest/vhost-user-test: add a test case for memory-backend-shm
> 
>  docs/system/devices/vhost-user.rst        |   5 +-
>  meson.build                               |   5 +-
>  qapi/qom.json                             |  17 +++
>  subprojects/libvhost-user/libvhost-user.h |   2 +-
>  backends/hostmem-shm.c                    | 123 ++++++++++++++++++++++
>  contrib/vhost-user-blk/vhost-user-blk.c   |  27 +++--
>  contrib/vhost-user-input/main.c           |  16 +--
>  hw/net/vhost_net.c                        |   5 +
>  subprojects/libvhost-user/libvhost-user.c |  76 ++++++++++++-
>  tests/qtest/vhost-user-blk-test.c         |   2 +-
>  tests/qtest/vhost-user-test.c             |  23 ++++
>  util/vhost-user-server.c                  |  12 +++
>  backends/meson.build                      |   1 +
>  hw/block/Kconfig                          |   2 +-
>  qemu-options.hx                           |  13 +++
>  util/meson.build                          |   4 +-
>  16 files changed, 305 insertions(+), 28 deletions(-)
>  create mode 100644 backends/hostmem-shm.c
> 
> -- 
> 2.45.0
> 

Acked-by: Stefan Hajnoczi <stefanha@redhat.com>

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