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authorPeter Maydell <peter.maydell@linaro.org>2015-11-19 16:26:08 +0000
committerPeter Maydell <peter.maydell@linaro.org>2015-11-19 16:26:08 +0000
commit348c32709fdbeb475dd072af49523cfdd75873f1 (patch)
tree7279674d55079522505ee2e91c1f6a180acfe92f /docs
parentc601a244a49f4e0be2539cbc5ffd288727cd4e89 (diff)
parent1c7ba94a184df1eddd589d5400d879568d3e5d08 (diff)
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Merge remote-tracking branch 'remotes/mst/tags/for_upstream' into staging
vhost, pc: fixes for 2.5 Fixes all over the place. This also re-enables a test we disabled in 2.5 cycle now that there's a way not to get a warning from it. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> # gpg: Signature made Thu 19 Nov 2015 13:27:43 GMT using RSA key ID D28D5469 # gpg: Good signature from "Michael S. Tsirkin <mst@kernel.org>" # gpg: aka "Michael S. Tsirkin <mst@redhat.com>" * remotes/mst/tags/for_upstream: exec: silence hugetlbfs warning under qtest tests: re-enable vhost-user-test acpi: fix buffer overrun on migration vhost-user: fix log size vhost-user: ignore qemu-only features specs/vhost-user: fix spec to match reality tests/vhost-user-bridge: implement logging of dirty pages i440fx: print an error message if user tries to enable iommu q35: Check propery to determine if iommu is set vhost-user: start/stop all rings vhost-user: print original request on error vhost-user-test: support VHOST_USER_SET_VRING_ENABLE vhost-user: update spec description vhost: don't send RESET_OWNER at stop vhost: let SET_VRING_ENABLE message depends on protocol feature Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Diffstat (limited to 'docs')
-rw-r--r--docs/specs/vhost-user.txt70
1 files changed, 61 insertions, 9 deletions
diff --git a/docs/specs/vhost-user.txt b/docs/specs/vhost-user.txt
index 26dde2e..7b9cd6d 100644
--- a/docs/specs/vhost-user.txt
+++ b/docs/specs/vhost-user.txt
@@ -87,6 +87,14 @@ Depending on the request type, payload can be:
User address: a 64-bit user address
mmap offset: 64-bit offset where region starts in the mapped memory
+* Log description
+ ---------------------------
+ | log size | log offset |
+ ---------------------------
+ log size: size of area used for logging
+ log offset: offset from start of supplied file descriptor
+ where logging starts (i.e. where guest address 0 would be logged)
+
In QEMU the vhost-user message is implemented with the following struct:
typedef struct VhostUserMsg {
@@ -138,6 +146,29 @@ As older slaves don't support negotiating protocol features,
a feature bit was dedicated for this purpose:
#define VHOST_USER_F_PROTOCOL_FEATURES 30
+Starting and stopping rings
+----------------------
+Client must only process each ring when it is both started and enabled.
+
+If VHOST_USER_F_PROTOCOL_FEATURES has not been negotiated, the ring is initialized
+in an enabled state.
+
+If VHOST_USER_F_PROTOCOL_FEATURES has been negotiated, the ring is initialized
+in a disabled state. Client must not process it until ring is enabled by
+VHOST_USER_SET_VRING_ENABLE with parameter 1, or after it has been disabled by
+VHOST_USER_SET_VRING_ENABLE with parameter 0.
+
+Each ring is initialized in a stopped state, client must not process it until
+ring is started, or after it has been stopped.
+
+Client must start ring upon receiving a kick (that is, detecting that file
+descriptor is readable) on the descriptor specified by
+VHOST_USER_SET_VRING_KICK, and stop ring upon receiving
+VHOST_USER_GET_VRING_BASE.
+
+While processing the rings (when they are started and enabled), client must
+support changing some configuration aspects on the fly.
+
Multiple queue support
----------------------
@@ -162,9 +193,13 @@ the slave makes to the memory mapped regions. The client should mark
the dirty pages in a log. Once it complies to this logging, it may
declare the VHOST_F_LOG_ALL vhost feature.
+To start/stop logging of data/used ring writes, server may send messages
+VHOST_USER_SET_FEATURES with VHOST_F_LOG_ALL and VHOST_USER_SET_VRING_ADDR with
+VHOST_VRING_F_LOG in ring's flags set to 1/0, respectively.
+
All the modifications to memory pointed by vring "descriptor" should
be marked. Modifications to "used" vring should be marked if
-VHOST_VRING_F_LOG is part of ring's features.
+VHOST_VRING_F_LOG is part of ring's flags.
Dirty pages are of size:
#define VHOST_LOG_PAGE 0x1000
@@ -173,22 +208,35 @@ The log memory fd is provided in the ancillary data of
VHOST_USER_SET_LOG_BASE message when the slave has
VHOST_USER_PROTOCOL_F_LOG_SHMFD protocol feature.
-The size of the log may be computed by using all the known guest
-addresses. The log covers from address 0 to the maximum of guest
+The size of the log is supplied as part of VhostUserMsg
+which should be large enough to cover all known guest
+addresses. Log starts at the supplied offset in the
+supplied file descriptor.
+The log covers from address 0 to the maximum of guest
regions. In pseudo-code, to mark page at "addr" as dirty:
page = addr / VHOST_LOG_PAGE
log[page / 8] |= 1 << page % 8
+Where addr is the guest physical address.
+
Use atomic operations, as the log may be concurrently manipulated.
+Note that when logging modifications to the used ring (when VHOST_VRING_F_LOG
+is set for this ring), log_guest_addr should be used to calculate the log
+offset: the write to first byte of the used ring is logged at this offset from
+log start. Also note that this value might be outside the legal guest physical
+address range (i.e. does not have to be covered by the VhostUserMemory table),
+but the bit offset of the last byte of the ring must fall within
+the size supplied by VhostUserLog.
+
VHOST_USER_SET_LOG_FD is an optional message with an eventfd in
ancillary data, it may be used to inform the master that the log has
been modified.
-Once the source has finished migration, VHOST_USER_RESET_OWNER message
-will be sent by the source. No further update must be done before the
-destination takes over with new regions & rings.
+Once the source has finished migration, rings will be stopped by
+the source. No further update must be done before rings are
+restarted.
Protocol features
-----------------
@@ -259,11 +307,13 @@ Message types
* VHOST_USER_RESET_OWNER
Id: 4
- Equivalent ioctl: VHOST_RESET_OWNER
Master payload: N/A
- Issued when a new connection is about to be closed. The Master will no
- longer own this connection (and will usually close it).
+ This is no longer used. Used to be sent to request stopping
+ all rings, but some clients interpreted it to also discard
+ connection state (this interpretation would lead to bugs).
+ It is recommended that clients either ignore this message,
+ or use it to stop all rings.
* VHOST_USER_SET_MEM_TABLE
@@ -388,6 +438,8 @@ Message types
Master payload: vring state description
Signal slave to enable or disable corresponding vring.
+ This request should be sent only when VHOST_USER_F_PROTOCOL_FEATURES
+ has been negotiated.
* VHOST_USER_SEND_RARP