On Thu, Apr 07, 2022 at 03:36:54PM +0200, Kevin Wolf wrote: > While implementing a vhost-user-blk driver for libblkio, I found some > problems with VHOST_USER_ADD/REM_MEM_REG both in the spec and in the > implementations in QEMU and libvhost-user that this series addresses. > > I also noticed that you can use REM_MEM_REG or SET_MEM_TABLE to unmap a > memory region that is still in use (e.g. a block I/O request using > addresses from the region has been started, but not completed yet), > which is not great. I'm not sure how to fix this best, though. > > We would have to wait for these requests to complete (maybe introduce a > refcount and wait for it to drop to zero), but waiting seems impossible > in libvhost-user because it doesn't have any main loop integration. Just > failing the memory region removal would be safe, but potentially a > rather awkward interface because clients would have to implement some > retry logic. > > Kevin Wolf (3): > docs/vhost-user: Clarifications for VHOST_USER_ADD/REM_MEM_REG > libvhost-user: Fix extra vu_add/rem_mem_reg reply > vhost-user: Don't pass file descriptor for VHOST_USER_REM_MEM_REG > > docs/interop/vhost-user.rst | 17 +++++++++++++++++ > hw/virtio/vhost-user.c | 2 +- > subprojects/libvhost-user/libvhost-user.c | 17 +++++++---------- > 3 files changed, 25 insertions(+), 11 deletions(-) > > -- > 2.35.1 >
Reviewed-by: Stefan Hajnoczi <stefa...@redhat.com>
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