24 Feb, 2010
1 commit
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There's currently no way for a virtio driver to ask for unused
buffers, so it has to keep a list itself to reclaim them at shutdown.
This is redundant, since virtio_ring stores that information. So
add a new hook to do this.Signed-off-by: Shirley Ma
Signed-off-by: Amit Shah
Signed-off-by: Rusty Russell
23 Sep, 2009
1 commit
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This API change means that virtio_net can tell how much capacity
remains for buffers. It's necessarily fuzzy, since
VIRTIO_RING_F_INDIRECT_DESC means we can fit any number of descriptors
in one, *if* we can kmalloc.Signed-off-by: Rusty Russell
Cc: Dinesh Subhraveti
12 Jun, 2009
2 commits
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Add a linked list of all virtqueues for a virtio device: this helps for
debugging and is also needed for upcoming interface change.Also, add a "name" field for clearer debug messages.
Signed-off-by: Rusty Russell
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Signed-off-by: Rusty Russell
02 May, 2008
1 commit
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A recent proposed feature addition to the virtio block driver revealed
some flaws in the API: in particular, we assume that feature
negotiation is complete once a driver's probe function returns.There is nothing in the API to require this, however, and even I
didn't notice when it was violated.So instead, we require the driver to specify what features it supports
in a table, we can then move the feature negotiation into the virtio
core. The intersection of device and driver features are presented in
a new 'features' bitmap in the struct virtio_device.Note that this highlights the difference between Linux unsigned-long
bitmaps where each unsigned long is in native endian, and a
straight-forward little-endian array of bytes.Drivers can still remove feature bits in their probe routine if they
really have to.API changes:
- dev->config->feature() no longer gets and acks a feature.
- drivers should advertise their features in the 'feature_table' field
- use virtio_has_feature() for extra sanity when checking feature bitsSigned-off-by: Rusty Russell
08 Apr, 2008
1 commit
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The 'disable_cb' callback is designed as an optimization to tell the host
we don't need callbacks now. As it is not reliable, the debug check is
overzealous: it can happen on two CPUs at the same time. Document this.Even if it were reliable, the virtio_net driver doesn't disable
callbacks on transmit so the START_USE/END_USE debugging reentrance
protection can be easily tripped even on UP.Thanks to Balaji Rao for the bug report and testing.
Signed-off-by: Rusty Russell
CC: Balaji Rao
Signed-off-by: Linus Torvalds
17 Mar, 2008
1 commit
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There is a race in virtio_net, dealing with disabling/enabling the callback.
I saw the following oops:kernel BUG at /space/kvm/drivers/virtio/virtio_ring.c:218!
illegal operation: 0001 [#1] SMP
Modules linked in: sunrpc dm_mod
CPU: 2 Not tainted 2.6.25-rc1zlive-host-10623-gd358142-dirty #99
Process swapper (pid: 0, task: 000000000f85a610, ksp: 000000000f873c60)
Krnl PSW : 0404300180000000 00000000002b81a6 (vring_disable_cb+0x16/0x20)
R:0 T:1 IO:0 EX:0 Key:0 M:1 W:0 P:0 AS:0 CC:3 PM:0 EA:3
Krnl GPRS: 0000000000000001 0000000000000001 0000000010005800 0000000000000001
000000000f3a0900 000000000f85a610 0000000000000000 0000000000000000
0000000000000000 000000000f870000 0000000000000000 0000000000001237
000000000f3a0920 000000000010ff74 00000000002846f6 000000000fa0bcd8
Krnl Code: 00000000002b819a: a7110001 tmll %r1,1
00000000002b819e: a7840004 brc 8,2b81a6
00000000002b81a2: a7f40001 brc 15,2b81a4
>00000000002b81a6: a51b0001 oill %r1,1
00000000002b81aa: 40102000 sth %r1,0(%r2)
00000000002b81ae: 07fe bcr 15,%r14
00000000002b81b0: eb7ff0380024 stmg %r7,%r15,56(%r15)
00000000002b81b6: a7f13e00 tmll %r15,15872
Call Trace:
([] 0xfa0bcd0)
[] vring_interrupt+0x5c/0x6c
[] do_extint+0xb8/0xf0
[] ext_no_vtime+0x16/0x1a
[] cpu_idle+0x1c2/0x1e0The problem can be triggered with a high amount of host->guest traffic.
I think its the following race:poll says netif_rx_complete
poll calls enable_cb
enable_cb opens the interrupt mask
a new packet comes, an interrupt is triggered----\
enable_cb sees that there is more work |
enable_cb disables the interrupt |
. V
. interrupt is delivered
. skb_recv_done does atomic napi test, ok
some waiting disable_cb is called->check fails->bang!
.
poll would do napi check
poll would do disable_cbThe fix is to let enable_cb not disable the interrupt again, but expect the
caller to do the cleanup if it returns false. In that case, the interrupt is
only disabled, if the napi test_set_bit was successful.Signed-off-by: Christian Borntraeger
Signed-off-by: Rusty Russell (cleaned up doco)
04 Feb, 2008
3 commits
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A reset function solves three problems:
1) It allows us to renegotiate features, eg. if we want to upgrade a
guest driver without rebooting the guest.2) It gives us a clean way of shutting down virtqueues: after a reset,
we know that the buffers won't be used by the host, and3) It helps the guest recover from messed-up drivers.
So we remove the ->shutdown hook, and the only way we now remove
feature bits is via reset.We leave it to the driver to do the reset before it deletes queues:
the balloon driver, for example, needs to chat to the host in its
remove function.Signed-off-by: Rusty Russell
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Various drivers want to know when their configuration information
changes: the balloon driver is the immediate user, but the network
driver may one day have a "carrier" status as well.This introduces that callback (lguest doesn't use it yet).
Signed-off-by: Rusty Russell
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It seems that virtio_net wants to disable callbacks (interrupts) before
calling netif_rx_schedule(), so we can't use the return value to do so.Rename "restart" to "cb_enable" and introduce "cb_disable" hook: callback
now returns void, rather than a boolean.Signed-off-by: Rusty Russell
23 Oct, 2007
1 commit
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This attempts to implement a "virtual I/O" layer which should allow
common drivers to be efficiently used across most virtual I/O
mechanisms. It will no-doubt need further enhancement.The virtio drivers add buffers to virtio queues; as the buffers are consumed
the driver "interrupt" callbacks are invoked.There is also a generic implementation of config space which drivers can query
to get setup information from the host.Signed-off-by: Rusty Russell
Cc: Dor Laor
Cc: Arnd Bergmann