[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [RFC v2 16/32] vhost+postcopy: Send address back to qem
|
From: |
Peter Xu |
|
Subject: |
Re: [Qemu-devel] [RFC v2 16/32] vhost+postcopy: Send address back to qemu |
|
Date: |
Wed, 13 Sep 2017 12:29:54 +0800 |
|
User-agent: |
Mutt/1.5.24 (2015-08-30) |
On Tue, Sep 12, 2017 at 06:15:13PM +0100, Dr. David Alan Gilbert wrote:
> * Peter Xu (address@hidden) wrote:
> > On Thu, Aug 24, 2017 at 08:27:14PM +0100, Dr. David Alan Gilbert (git)
> > wrote:
> > > From: "Dr. David Alan Gilbert" <address@hidden>
> > >
> > > We need a better way, but at the moment we need the address of the
> > > mappings sent back to qemu so it can interpret the messages on the
> > > userfaultfd it reads.
> > >
> > > Note: We don't ask for the default 'ack' reply since we've got our own.
> > >
> > > Signed-off-by: Dr. David Alan Gilbert <address@hidden>
> > > ---
> > > contrib/libvhost-user/libvhost-user.c | 15 ++++++++-
> > > docs/interop/vhost-user.txt | 6 ++++
> > > hw/virtio/trace-events | 1 +
> > > hw/virtio/vhost-user.c | 57
> > > ++++++++++++++++++++++++++++++++++-
> > > 4 files changed, 77 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/contrib/libvhost-user/libvhost-user.c
> > > b/contrib/libvhost-user/libvhost-user.c
> > > index e6ab059a03..5ec54f7d60 100644
> > > --- a/contrib/libvhost-user/libvhost-user.c
> > > +++ b/contrib/libvhost-user/libvhost-user.c
> > > @@ -477,13 +477,26 @@ vu_set_mem_table_exec(VuDev *dev, VhostUserMsg
> > > *vmsg)
> > > DPRINT("%s: region %d: Registered userfault for %llx +
> > > %llx\n",
> > > __func__, i, reg_struct.range.start,
> > > reg_struct.range.len);
> > > /* TODO: Stash 'zero' support flags somewhere */
> > > - /* TODO: Get address back to QEMU */
> > >
> > > + /* TODO: We need to find a way for the qemu not to see the
> > > virtual
> > > + * addresses of the clients, so as to keep better separation.
> > > + */
> > > + /* Return the address to QEMU so that it can translate the
> > > ufd
> > > + * fault addresses back.
> > > + */
> > > + msg_region->userspace_addr = (uintptr_t)(mmap_addr +
> > > +
> > > dev_region->mmap_offset);
> > > }
> > >
> > > close(vmsg->fds[i]);
> > > }
> > >
> > > + if (dev->postcopy_listening) {
> > > + /* Need to return the addresses - send the updated message back
> > > */
> > > + vmsg->fd_num = 0;
> > > + return true;
> > > + }
> > > +
> > > return false;
> > > }
> > >
> > > diff --git a/docs/interop/vhost-user.txt b/docs/interop/vhost-user.txt
> > > index 73c3dd74db..b2a548c94d 100644
> > > --- a/docs/interop/vhost-user.txt
> > > +++ b/docs/interop/vhost-user.txt
> > > @@ -413,12 +413,18 @@ Master message types
> > > Id: 5
> > > Equivalent ioctl: VHOST_SET_MEM_TABLE
> > > Master payload: memory regions description
> > > + Slave payload: (postcopy only) memory regions description
> > >
> > > Sets the memory map regions on the slave so it can translate the
> > > vring
> > > addresses. In the ancillary data there is an array of file
> > > descriptors
> > > for each memory mapped region. The size and ordering of the fds
> > > matches
> > > the number and ordering of memory regions.
> > >
> > > + When postcopy-listening has been received, SET_MEM_TABLE replies
> > > with
> > > + the bases of the memory mapped regions to the master. It must
> > > have mmap'd
> > > + the regions and enabled userfaultfd on them. Note NEED_REPLY_MASK
> > > + is not set in this case.
> > > +
> > > * VHOST_USER_SET_LOG_BASE
> > >
> > > Id: 6
> > > diff --git a/hw/virtio/trace-events b/hw/virtio/trace-events
> > > index f736c7c84f..63fd4a79cf 100644
> > > --- a/hw/virtio/trace-events
> > > +++ b/hw/virtio/trace-events
> > > @@ -2,6 +2,7 @@
> > >
> > > # hw/virtio/vhost-user.c
> > > vhost_user_postcopy_listen(void) ""
> > > +vhost_user_set_mem_table_postcopy(uint64_t client_addr, uint64_t qhva,
> > > int reply_i, int region_i) "client:0x%"PRIx64" for hva: 0x%"PRIx64" reply
> > > %d region %d"
> > >
> > > # hw/virtio/virtio.c
> > > virtqueue_alloc_element(void *elem, size_t sz, unsigned in_num, unsigned
> > > out_num) "elem %p size %zd in_num %u out_num %u"
> > > diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
> > > index 9178271ab2..2e4eb0864a 100644
> > > --- a/hw/virtio/vhost-user.c
> > > +++ b/hw/virtio/vhost-user.c
> > > @@ -19,6 +19,7 @@
> > > #include "qemu/sockets.h"
> > > #include "migration/migration.h"
> > > #include "migration/postcopy-ram.h"
> > > +#include "trace.h"
> > >
> > > #include <sys/ioctl.h>
> > > #include <sys/socket.h>
> > > @@ -133,6 +134,7 @@ struct vhost_user {
> > > int slave_fd;
> > > NotifierWithReturn postcopy_notifier;
> > > struct PostCopyFD postcopy_fd;
> > > + uint64_t postcopy_client_bases[VHOST_MEMORY_MAX_NREGIONS];
> > > };
> > >
> > > static bool ioeventfd_enabled(void)
> > > @@ -300,11 +302,13 @@ static int vhost_user_set_log_base(struct vhost_dev
> > > *dev, uint64_t base,
> > > static int vhost_user_set_mem_table(struct vhost_dev *dev,
> > > struct vhost_memory *mem)
> > > {
> > > + struct vhost_user *u = dev->opaque;
> > > int fds[VHOST_MEMORY_MAX_NREGIONS];
> > > int i, fd;
> > > size_t fd_num = 0;
> > > bool reply_supported = virtio_has_feature(dev->protocol_features,
> > > -
> > > VHOST_USER_PROTOCOL_F_REPLY_ACK);
> > > +
> > > VHOST_USER_PROTOCOL_F_REPLY_ACK) &&
> > > + !u->postcopy_fd.handler;
> >
> > (indent)
>
> Fixed
>
> > >
> > > VhostUserMsg msg = {
> > > .request = VHOST_USER_SET_MEM_TABLE,
> > > @@ -350,6 +354,57 @@ static int vhost_user_set_mem_table(struct vhost_dev
> > > *dev,
> > > return -1;
> > > }
> > >
> > > + if (u->postcopy_fd.handler) {
> >
> > It seems that after this handler is set, we never clean it up. Do we
> > need to unset it somewhere? (maybe vhost_user_postcopy_end?)
>
> Hmm yes I'll have a look at that.
>
> > > + VhostUserMsg msg_reply;
> > > + int region_i, reply_i;
> > > + if (vhost_user_read(dev, &msg_reply) < 0) {
> > > + return -1;
> > > + }
> > > +
> > > + if (msg_reply.request != VHOST_USER_SET_MEM_TABLE) {
> > > + error_report("%s: Received unexpected msg type."
> > > + "Expected %d received %d", __func__,
> > > + VHOST_USER_SET_MEM_TABLE, msg_reply.request);
> > > + return -1;
> > > + }
> > > + /* We're using the same structure, just reusing one of the
> > > + * fields, so it should be the same size.
> > > + */
> > > + if (msg_reply.size != msg.size) {
> > > + error_report("%s: Unexpected size for postcopy reply "
> > > + "%d vs %d", __func__, msg_reply.size, msg.size);
> > > + return -1;
> > > + }
> > > +
> > > + memset(u->postcopy_client_bases, 0,
> > > + sizeof(uint64_t) * VHOST_MEMORY_MAX_NREGIONS);
> > > +
> > > + /* They're in the same order as the regions that were sent
> > > + * but some of the regions were skipped (above) if they
> > > + * didn't have fd's
> > > + */
> > > + for (reply_i = 0, region_i = 0;
> > > + region_i < dev->mem->nregions;
> > > + region_i++) {
> > > + if (reply_i < fd_num &&
> > > +
> > > msg_reply.payload.memory.regions[region_i].guest_phys_addr ==
> > ^^^^^^^^
> > should this be reply_i?
>
> Yes it should - nicely spotted
>
> > (And maybe we can use pointers for the regions for better readability?)
>
> I'm nervous of doing that since VhostUserMsg is 'packed' - and I'm not
> convinced it's legal to take a pointer to a member (although I think
> we do it in a whole bunch of places and clang moans about it).
Could I ask why packed struct is not suitable for taking field
pointers out of the structs? I hardly use clang, and I feel like
there is something I may have missed in C programming...
>
> > > + dev->mem->regions[region_i].guest_phys_addr) {
> > > + u->postcopy_client_bases[region_i] =
> > > +
> > > msg_reply.payload.memory.regions[reply_i].userspace_addr;
> > > + trace_vhost_user_set_mem_table_postcopy(
> > > +
> > > msg_reply.payload.memory.regions[reply_i].userspace_addr,
> > > + msg.payload.memory.regions[reply_i].userspace_addr,
> ^^^^^^^
> and I think this one is region_i
Hmm... shouldn't msg.payload.memory.regions[] defined with size
VHOST_MEMORY_MAX_NREGIONS as well?
--
Peter Xu