Commit Graph

6 Commits

Author SHA1 Message Date
Thomas Huth 5a0e75f0a9 hw/misc/ivshmem: Remove deprecated "ivshmem" legacy device
It's been marked as deprecated in QEMU v2.6.0 already, so really nobody
should use the legacy "ivshmem" device anymore (but use ivshmem-plain or
ivshmem-doorbell instead). Time to remove the deprecated device now.

Belatedly also update a mention of the deprecated "ivshmem" in the file
docs/specs/ivshmem-spec.txt to "ivshmem-doorbell". Missed in commit
5400c02b90 ("ivshmem: Split ivshmem-plain, ivshmem-doorbell off ivshmem").

Signed-off-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2019-01-14 19:31:04 -05:00
Markus Armbruster 62a830b688 ivshmem: Require master to have ID zero
Migration with ivshmem needs to be carefully orchestrated to work.
Exactly one peer (the "master") migrates to the destination, all other
peers need to unplug (and disconnect), migrate, plug back (and
reconnect).  This is sort of documented in qemu-doc.

If peers connect on the destination before migration completes, the
shared memory can get messed up.  This isn't documented anywhere.  Fix
that in qemu-doc.

To avoid messing up register IVPosition on migration, the server must
assign the same ID on source and destination.  ivshmem-spec.txt leaves
ID assignment unspecified, however.

Amend ivshmem-spec.txt to require the first client to receive ID zero.
The example ivshmem-server complies: it always assigns the first
unused ID.

For a bit of additional safety, enforce ID zero for the master.  This
does nothing when we're not using a server, because the ID is zero for
all peers then.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <1458066895-20632-40-git-send-email-armbru@redhat.com>
2016-03-21 21:29:03 +01:00
Markus Armbruster 5400c02b90 ivshmem: Split ivshmem-plain, ivshmem-doorbell off ivshmem
ivshmem can be configured with and without interrupt capability
(a.k.a. "doorbell").  The two configurations have largely disjoint
options, which makes for a confusing (and badly checked) user
interface.  Moreover, the device can't tell the guest whether its
doorbell is enabled.

Create two new device models ivshmem-plain and ivshmem-doorbell, and
deprecate the old one.

Changes from ivshmem:

* PCI revision is 1 instead of 0.  The new revision is fully backwards
  compatible for guests.  Guests may elect to require at least
  revision 1 to make sure they're not exposed to the funny "no shared
  memory, yet" state.

* Property "role" replaced by "master".  role=master becomes
  master=on, role=peer becomes master=off.  Default is off instead of
  auto.

* Property "use64" is gone.  The new devices always have 64 bit BARs.

Changes from ivshmem to ivshmem-plain:

* The Interrupt Pin register in PCI config space is zero (does not use
  an interrupt pin) instead of one (uses INTA).

* Property "x-memdev" is renamed to "memdev".

* Properties "shm" and "size" are gone.  Use property "memdev"
  instead.

* Property "msi" is gone.  The new device can't have MSI-X capability.
  It can't interrupt anyway.

* Properties "ioeventfd" and "vectors" are gone.  They're meaningless
  without interrupts anyway.

Changes from ivshmem to ivshmem-doorbell:

* Property "msi" is gone.  The new device always has MSI-X capability.

* Property "ioeventfd" defaults to on instead of off.

* Property "size" is gone.  The new device can only map all the shared
  memory received from the server.

Guests can easily find out whether the device is configured for
interrupts by checking for MSI-X capability.

Note: some code added in sub-optimal places to make the diff easier to
review.  The next commit will move it to more sensible places.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <1458066895-20632-37-git-send-email-armbru@redhat.com>
2016-03-21 21:29:03 +01:00
Markus Armbruster 1309cf448a ivshmem: Propagate errors through ivshmem_recv_setup()
This kills off the funny state described in the previous commit.

Simplify ivshmem_io_read() accordingly, and update documentation.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <1458066895-20632-27-git-send-email-armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
2016-03-21 21:29:01 +01:00
Markus Armbruster 71c265816d ivshmem: Don't destroy the chardev on version mismatch
Yes, the chardev is commonly useless after we read a bad version from
it, but destroying it is inappropriate anyway: the user created it, so
the user should be able to hold on to it as long as he likes.  We
don't destroy it on other errors.  Screwed up in commit 5105b1d.

Stop reading instead.

Also note QEMU's behavior in ivshmem-spec.txt.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <1458066895-20632-16-git-send-email-armbru@redhat.com>
2016-03-21 21:29:00 +01:00
Markus Armbruster fdee2025dd ivshmem: Rewrite specification document
This started as an attempt to update ivshmem_device_spec.txt for
clarity, accuracy and completeness while working on its code, and
quickly became a full rewrite.  Since the diff would be useless
anyway, I'm using the opportunity to rename the file to
ivshmem-spec.txt.

I tried hard to ensure the new text contradicts neither the old text
nor the code.  If the new text contradicts the old text but not the
code, it's probably a bug in the old text.  If the new text
contradicts both, its probably a bug in the new text.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <1458066895-20632-11-git-send-email-armbru@redhat.com>
2016-03-21 21:28:59 +01:00