Commit Graph

81 Commits

Author SHA1 Message Date
Rusty Russell 1842f23c05 lguest and virtio: cleanup struct definitions to Linux style.
I've been doing this for years, and akpm picked me up on it about 12
months ago.  lguest partly serves as example code, so let's do it Right.

Also, remove two unused fields in struct vblk_info in the example launcher.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Ingo Molnar <mingo@redhat.com>
2009-07-30 16:03:46 +09:30
Rusty Russell a91d74a3c4 lguest: update commentry
Every so often, after code shuffles, I need to go through and unbitrot
the Lguest Journey (see drivers/lguest/README).  Since we now use RCU in
a simple form in one place I took the opportunity to expand that explanation.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
2009-07-30 16:03:46 +09:30
Rusty Russell 2e04ef7691 lguest: fix comment style
I don't really notice it (except to begrudge the extra vertical
space), but Ingo does.  And he pointed out that one excuse of lguest
is as a teaching tool, it should set a good example.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Ingo Molnar <mingo@redhat.com>
2009-07-30 16:03:45 +09:30
Rusty Russell 8ef562d112 lguest: fix descriptor corruption in example launcher
1d589bb16b "Add serial number support
for virtio_blk, V4a" extended 'struct virtio_blk_config' to 536 bytes.
Lguest and S/390 both use an 8 bit value for the feature length, and
this change broke them (if the code is naive).

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: John Cooper <john.cooper@redhat.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
2009-07-30 16:03:43 +09:30
Mark McLoughlin d1f0132e76 lguest: add support for indirect ring entries
Support the VIRTIO_RING_F_INDIRECT_DESC feature.

This is a simple matter of changing the descriptor walking
code to operate on a struct vring_desc* and supplying it
with an indirect table if detected.

Signed-off-by: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2009-06-12 22:27:13 +09:30
Rusty Russell b60da13fc7 lguest: suppress notifications in example Launcher
The Guest only really needs to tell us about activity when we're going
to listen to the eventfd: normally, we don't want to know.

So if there are no available buffers, turn on notifications, re-check,
then wait for the Guest to notify us via the eventfd, then turn
notifications off again.

There's enough else going on that the differences are in the noise.

Before:				Secs	RxKicks	TxKicks
 1G TCP Guest->Host:		3.94	  4686	  32815
 1M normal pings:		104	142862	1000010
 1M 1k pings (-l 120):		57	142026	1000007

After:
 1G TCP Guest->Host:		3.76	  4691	  32811
 1M normal pings:		111	142859	 997467
 1M 1k pings (-l 120):		55	 19648	 501549

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2009-06-12 22:27:13 +09:30
Rusty Russell 4a8962e21b lguest: try to batch interrupts on network receive
Rather than triggering an interrupt every time, we only trigger an
interrupt when there are no more incoming packets (or the recv queue
is full).

However, the overhead of doing the select to figure this out is
measurable: 1M pings goes from 98 to 104 seconds, and 1G Guest->Host
TCP goes from 3.69 to 3.94 seconds.  It's close to the noise though.

I tested various timeouts, including reducing it as the number of
pending packets increased, timing a 1 gigabyte TCP send from Guest ->
Host and Host -> Guest (GSO disabled, to increase packet rate).

// time tcpblast -o -s 65536 -c 16k 192.168.2.1:9999 > /dev/null

Timeout		Guest->Host	Pkts/irq	Host->Guest	Pkts/irq
Before		11.3s		1.0		6.3s		1.0
0		11.7s		1.0		6.6s		23.5
1		17.1s		8.8		8.6s		26.0
1/pending	13.4s		1.9		6.6s		23.8
2/pending	13.6s		2.8		6.6s		24.1
5/pending	14.1s		5.0		6.6s		24.4

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2009-06-12 22:27:12 +09:30
Rusty Russell 95c517c09b lguest: avoid sending interrupts to Guest when no activity occurs.
If we track how many buffers we've used, we can tell whether we really
need to interrupt the Guest.  This happens as a side effect of
spurious notifications.

Spurious notifications happen because it can take a while before the
Host thread wakes up and sets the VRING_USED_F_NO_NOTIFY flag, and
meanwhile the Guest can more notifications.

A real fix would be to use wake counts, rather than a suppression
flag, but the practical difference is generally in the noise: the
interrupt is usually coalesced into a pending one anyway so we just
save a system call which isn't clearly measurable.

				Secs	Spurious IRQS
1G TCP Guest->Host:		3.93	58
1M normal pings:		100	72
1M 1k pings (-l 120):		57	492904

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2009-06-12 22:27:12 +09:30
Rusty Russell 38bc2b8c56 lguest: implement deferred interrupts in example Launcher
Rather than sending an interrupt on every buffer, we only send an interrupt
when we're about to wait for the Guest to send us a new one.  The console
input and network input still send interrupts manually, but the block device,
network and console output queues can simply rely on this logic to send
interrupts to the Guest at the right time.

The patch is cluttered by moving trigger_irq() higher in the code.

In practice, two factors make this optimization less interesting:
(1) we often only get one input at a time, even for networking,
(2) triggering an interrupt rapidly tends to get coalesced anyway.

Before:				Secs	RxIRQS	TxIRQs
 1G TCP Guest->Host:		3.72	32784	32771
 1M normal pings:		99	1000004	995541
 100,000 1k pings (-l 120):	5	49510	49058

After:
 1G TCP Guest->Host:		3.69	32809	32769
 1M normal pings:		99	1000004	996196
 100,000 1k pings (-l 120):	5	52435	52361

(Note the interrupt count on 100k pings goes *up*: see next patch).

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2009-06-12 22:27:11 +09:30
Rusty Russell 659a0e6633 lguest: have example Launcher service all devices in separate threads
Currently lguest has three threads: the main Launcher thread, a Waker
thread, and a thread for the block device (because synchronous block
was simply too painful to bear).

The Waker selects() on all the input file descriptors (eg. stdin, net
devices, pipe to the block thread) and when one becomes readable it calls
into the kernel to kick the Launcher thread out into userspace, which
repeats the poll, services the device(s), and then tells the kernel to
release the Waker before re-entering the kernel to run the Guest.

Also, to make a slightly-decent network transmit routine, the Launcher
would suppress further network interrupts while it set a timer: that
signal handler would write to a pipe, which would rouse the Waker
which would prod the Launcher out of the kernel to check the network
device again.

Now we can convert all our virtqueues to separate threads: each one has
a separate eventfd for when the Guest pokes the device, and can trigger
interrupts in the Guest directly.

The linecount shows how much this simplifies, but to really bring it
home, here's an strace analysis of single Guest->Host ping before:

* Guest sends packet, notifies xmit vq, return control to Launcher
* Launcher clears notification flag on xmit ring
* Launcher writes packet to TUN device
	writev(4, [{"\0\0\0\0\0\0\0\0\0\0", 10}, {"\366\r\224`\2058\272m\224vf\274\10\0E\0\0T\0\0@\0@\1\265"..., 98}], 2) = 108
* Launcher sets up interrupt for Guest (xmit ring is empty)
	write(10, "\2\0\0\0\3\0\0\0", 8) = 0
* Launcher sets up timer for interrupt mitigation
	setitimer(ITIMER_REAL, {it_interval={0, 0}, it_value={0, 505}}, NULL) = 0
* Launcher re-runs guest
	pread64(10, 0xbfa5f4d4, 4, 0) ...
* Waker notices reply packet in tun device (it was in select)
	select(12, [0 3 4 6 11], NULL, NULL, NULL) = 1 (in [4])
* Waker kicks Launcher out of guest:
	pwrite64(10, "\3\0\0\0\1\0\0\0", 8, 0) = 0
* Launcher returns from running guest:
	... = -1 EAGAIN (Resource temporarily unavailable)
* Launcher looks at input fds:
	select(7, [0 3 4 6], NULL, NULL, {0, 0}) = 1 (in [4], left {0, 0})
* Launcher reads pong from tun device:
	readv(4, [{"\0\0\0\0\0\0\0\0\0\0", 10}, {"\272m\224vf\274\366\r\224`\2058\10\0E\0\0T\364\26\0\0@"..., 1518}], 2) = 108
* Launcher injects guest notification:
	write(10, "\2\0\0\0\2\0\0\0", 8) = 0
* Launcher rechecks fds:
	select(7, [0 3 4 6], NULL, NULL, {0, 0}) = 0 (Timeout)
* Launcher clears Waker:
	pwrite64(10, "\3\0\0\0\0\0\0\0", 8, 0) = 0
* Launcher reruns Guest:
	pread64(10, 0xbfa5f4d4, 4, 0) = ? ERESTARTSYS (To be restarted)
* Signal comes in, uses pipe to wake up Launcher:
	--- SIGALRM (Alarm clock) @ 0 (0) ---
	write(8, "\0", 1)       = 1
	sigreturn()             = ? (mask now [])
* Waker sees write on pipe:
	select(12, [0 3 4 6 11], NULL, NULL, NULL) = 1 (in [6])
* Waker kicks Launcher out of Guest:
	pwrite64(10, "\3\0\0\0\1\0\0\0", 8, 0) = 0
* Launcher exits from kernel:
	pread64(10, 0xbfa5f4d4, 4, 0) = -1 EAGAIN (Resource temporarily unavailable)
* Launcher looks to see what fd woke it:
	select(7, [0 3 4 6], NULL, NULL, {0, 0}) = 1 (in [6], left {0, 0})
* Launcher reads timeout fd, sets notification flag on xmit ring
	read(6, "\0", 32)       = 1
* Launcher rechecks fds:
	select(7, [0 3 4 6], NULL, NULL, {0, 0}) = 0 (Timeout)
* Launcher clears Waker:
	pwrite64(10, "\3\0\0\0\0\0\0\0", 8, 0) = 0
* Launcher resumes Guest:
	pread64(10, "\0p\0\4", 4, 0) ....

strace analysis of single Guest->Host ping after:

* Guest sends packet, notifies xmit vq, creates event on eventfd.
* Network xmit thread wakes from read on eventfd:
	read(7, "\1\0\0\0\0\0\0\0", 8)          = 8
* Network xmit thread writes packet to TUN device
	writev(4, [{"\0\0\0\0\0\0\0\0\0\0", 10}, {"J\217\232FI\37j\27\375\276\0\304\10\0E\0\0T\0\0@\0@\1\265"..., 98}], 2) = 108
* Network recv thread wakes up from read on tunfd:
	readv(4, [{"\0\0\0\0\0\0\0\0\0\0", 10}, {"j\27\375\276\0\304J\217\232FI\37\10\0E\0\0TiO\0\0@\1\214"..., 1518}], 2) = 108
* Network recv thread sets up interrupt for the Guest
	write(6, "\2\0\0\0\2\0\0\0", 8) = 0
* Network recv thread goes back to reading tunfd
	13:39:42.460285 readv(4,  <unfinished ...>
* Network xmit thread sets up interrupt for Guest (xmit ring is empty)
	write(6, "\2\0\0\0\3\0\0\0", 8) = 0
* Network xmit thread goes back to reading from eventfd
	read(7, <unfinished ...>

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2009-06-12 22:27:10 +09:30
Matias Zabaljauregui acdd0b6292 lguest: PAE support
This version requires that host and guest have the same PAE status.
NX cap is not offered to the guest, yet.

Signed-off-by: Matias Zabaljauregui <zabaljauregui@gmail.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2009-06-12 22:27:08 +09:30
Rusty Russell 7b5c806c35 lguest: fix writev returning short on console output
I've never seen it here, but I can't find anywhere that says writev
will write everything.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2009-06-12 22:27:05 +09:30
Rusty Russell e606490c44 lguest: clean up length-used value in example launcher
The "len" field in the used ring for virtio indicates the number of
bytes *written* to the buffer.  This means the guest doesn't have to
zero the buffers in advance as it always knows the used length.

Erroneously, the console and network example code puts the length
*read* into that field.  The guest ignores it, but it's wrong.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2009-06-12 22:27:05 +09:30
Rusty Russell 2644f17d6c lguest: clean up example launcher compile flags.
18 months ago 5bbf89fc26 changed to loading
bzImages directly, and no longer manually ungzipping them, so we no longer
need libz.

Also, -m32 is useful for those on 64-bit platforms (and harmless on
32-bit).

Reported-by: Ron Minnich <rminnich@gmail.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2009-06-12 22:27:03 +09:30
Rusty Russell ebf9a5a99c lguest: remove invalid interrupt forcing logic.
2088761152 (lguest: notify on empty) introduced
lguest support for the VIRTIO_F_NOTIFY_ON_EMPTY flag, but in fact it turned on
interrupts all the time.

Because we always process one buffer at a time, the inflight count is always 0
when call trigger_irq and so we always ignore VRING_AVAIL_F_NO_INTERRUPT from
the Guest.

It should be looking to see if there are more buffers in the Guest's queue:
if it's empty, then we force an interrupt.

This makes little difference, since we usually have an empty queue; but
that's the subject of another patch.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2009-06-12 22:27:02 +09:30
Rusty Russell f7027c6387 lguest: get more serious about wmb() in example Launcher code
Since the Launcher process runs the Guest, it doesn't have to be very
serious about its barriers: the Guest isn't running while we are (Guest
is UP).

Before we change to use threads to service devices, we need to fix this.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2009-06-12 22:27:00 +09:30
Rusty Russell 56739c802c lguest: cleanup passing of /dev/lguest fd around example launcher.
We hand the /dev/lguest fd everywhere; it's far neater to just make it
a global (it already is, in fact, hidden in the waker_fds struct).

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2009-06-12 22:26:59 +09:30
Rusty Russell 713b15b378 lguest: be paranoid about guest playing with device descriptors.
We can't trust the values in the device descriptor table once the
guest has booted, so keep local copies.  They could set them to
strange values then cause us to segv (they're 8 bit values, so they
can't make our pointers go too wild).

This becomes more important with the following patches which read them.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2009-06-12 22:26:59 +09:30
Rusty Russell 38cfe96804 lguest: document 32-bit and PAE requirements
Robert noted that we don't actually document that lguest is 32-bit only,
nor that PAE must be off (CONFIG_PAE is now prompted for if HIGHMEM is
set to "off).

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: lguest@ozlabs.org
Cc: "Robert P. J. Day" <rpjday@crashcourse.ca>
2009-04-19 23:14:02 +09:30
Matt Kraai 9536c26b31 lguest: tell git to ignore Documentation/lguest/lguest
This is the example lguest launcher binary.

Signed-off-by: Matt Kraai <kraai@ftbfs.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2009-04-19 23:14:02 +09:30
Rusty Russell d1881d3192 lguest: barrier me harder
Impact: barrier correctness in example launcher

I doubt either lguest user will complain about performance.

Reported-by: Christoph Hellwig <hch@infradead.org>
Cc: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2009-03-30 21:55:26 +10:30
Tim 'mithro' Ansell b44d49ab09 lguest: disable the FORTIFY for lguest.
Makes all the warnings go away when compiling lguest on Ubuntu on
Intrepid or greater.

Signed-off-by: Timothy R Ansell <mithro@mithis.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2009-01-30 11:34:10 +10:30
Matias Zabaljauregui 58a2456644 lguest: move the initial guest page table creation code to the host
This patch moves the initial guest page table creation code to the host,
so the launcher keeps working with PAE enabled configs.

Signed-off-by: Matias Zabaljauregui <zabaljauregui@gmail.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-12-30 09:26:11 +10:30
Rusty Russell 2966af73e7 virtio: use LGUEST_VRING_ALIGN instead of relying on pagesize
This doesn't really matter, since lguest is i386 only at the moment,
but we could actually choose a different value.  (lguest doesn't have
a guarenteed ABI).

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-12-30 09:26:02 +10:30
Rusty Russell d5d02d6dd3 lguest: fix example launcher compile after moved asm-x86 dir.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-10-31 11:24:27 +11:00
Uwe Hermann 71cced6eb0 doc/x86: fix doc subdirs
The Documentation/i386 and Documentation/x86_64 directories and their
contents have been moved into Documentation/x86. Fix references to
those files accordingly.

Signed-off-by: Uwe Hermann <uwe@hermann-uwe.de>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-10-28 16:36:42 +01:00
Rusty Russell 1dc3e3bcbf lguest: update commentry
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-08-26 00:19:28 +10:00
Rusty Russell 40c42076eb lguest: don't set MAC address for guest unless specified
This shows up when trying to bridge:
	tap0: received packet with  own address as source address

As Max Krasnyansky points out, there's no reason to give the guest the
same mac address as the TUN device.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Max Krasnyansky <maxk@qualcomm.com>
2008-08-12 17:52:52 +10:00
Rusty Russell 8c79873da0 lguest: turn Waker into a thread, not a process
lguest uses a Waker process to break it out of the kernel (ie.
actually running the guest) when file descriptor needs attention.

Changing this from a process to a thread somewhat simplifies things:
it can directly access the fd_set of things to watch.  More
importantly, it means that the Waker can see Guest memory correctly,
so /dev/vring file descriptors will work as anticipated (the
alternative is to actually mmap MAP_SHARED, but you can't do that with
/dev/zero).

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-07-29 09:58:39 +10:00
Rusty Russell 0f0c4fab82 lguest: Enlarge virtio rings
With big packets, 128 entries is a little small.

Guest -> Host 1GB TCP:
Before: 8.43625 seconds xmit 95640 recv 198266 timeout 49771 usec 1252
After: 8.01099 seconds xmit 49200 recv 102263 timeout 26014 usec 2118

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-07-29 09:58:38 +10:00
Rusty Russell 398f187d74 lguest: Use GSO/IFF_VNET_HDR extensions on tun/tap
Guest -> Host 1GB TCP:
Before 20.1974 seconds xmit 214510 recv 5 timeout 214491 usec 278
After 8.43625 seconds xmit 95640 recv 198266 timeout 49771 usec 1252

Host -> Guest 1GB TCP:
Before: Seconds 9.98854 xmit 172166 recv 5344 timeout 172157 usec 251
After: Seconds 5.72803 xmit 244322 recv 9919 timeout 244302 usec 156

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-07-29 09:58:37 +10:00
Rusty Russell 9254926f85 lguest: Remove 'network: no dma buffer!' warning
This warning can happen a lot under load, and it should be warnx not
warn anwyay.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-07-29 09:58:37 +10:00
Rusty Russell aa1249840b lguest: Adaptive timeout
Since the correct timeout value varies, use a heuristic which adjusts
the timeout depending on how many packets we've seen.  This gives
slightly worse results, but doesn't need tweaking when GSO is
introduced.

500 usec	19.1887		xmit 561141 recv 1 timeout 559657
Dynamic (278)	20.1974		xmit 214510 recv 5 timeout 214491 usec 278

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-07-29 09:58:36 +10:00
Rusty Russell a161883a29 lguest: Tell Guest net not to notify us on every packet xmit
virtio_ring has the ability to suppress notifications.  This prevents
a guest exit for every packet, but we need to set a timer on packet
receipt to re-check if there were any remaining packets.

Here are the times for 1G TCP Guest->Host with different timeout
settings (it matters because the TCP window doesn't grow big enough to
fill the entire buffer):

Timeout value	Seconds		Xmit/Recv/Timeout
None (before)	25.3784		xmit 7750233 recv 1
2500 usec	62.5119		xmit 207020 recv 2 timeout 207020
1000 usec	34.5379		xmit 207003 recv 2 timeout 207003
750 usec	29.2305		xmit 207002 recv 1 timeout 207002
500 usec	19.1887		xmit 561141 recv 1 timeout 559657
250 usec	20.0465		xmit 214128 recv 2 timeout 214110
100 usec	19.2583		xmit 561621 recv 1 timeout 560153

(Note that these values are sensitive to the GSO patches which come
 later, and probably other traffic-related variables, so take with a
 large grain of salt).

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-07-29 09:58:36 +10:00
Rusty Russell 5dae785a82 lguest: net block unneeded receive queue update notifications
Number of exits transmitting 10GB Guest->Host before:
	network xmit 7858610 recv 118136

After:
	network xmit 7750233 recv 1

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-07-29 09:58:35 +10:00
Rusty Russell b5111790fa lguest: wrap last_avail accesses.
To simplify the transition to when we publish indices in the ring
(and make shuffling my patch queue easier), wrap them in a lg_last_avail()
macro.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-07-29 09:58:35 +10:00
Rusty Russell 28fd6d7f95 lguest: virtio-rng support
This is a simple patch to add support for the virtio "hardware random
generator" to lguest.  It gets about 1.2 MB/sec reading from /dev/hwrng
in the guest.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-07-29 09:58:34 +10:00
Mark McLoughlin dec6a2be08 lguest: Support assigning a MAC address
If you've got a nice DHCP configuration which maps MAC
addresses to specific IP addresses, then you're going to
want to start your guest with one of those MAC addresses.

Also, in Fedora, we have persistent network interface naming
based on the MAC address, so with randomly assigned
addresses you're soon going to hit eth13. Who knows what
will happen then!

Allow assigning a MAC address to the network interface with
e.g.

  --tunnet=bridge:eth0:00:FF:95:6B:DA:3D

or:

  --tunnet=192.168.121.1:00:FF:95:6B:DA:3D

which is pretty unintelligable, but ...

(includes Rusty's minor rework)

Signed-off-by: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-07-29 09:58:33 +10:00
Mark McLoughlin 34bdaab44d lguest: Don't leak /dev/zero fd
Signed-off-by: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-07-29 09:58:33 +10:00
Rusty Russell 32c68e5c56 lguest: fix verbose printing of device features.
%02x is more appropriate for bytes than %08x.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-07-29 09:58:32 +10:00
Rusty Russell 2088761152 lguest: notify on empty
This is the lguest implementation of the VIRTIO_F_NOTIFY_ON_EMPTY feature.
It is currently only published for network devices, but it is turned on for
everyone.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-05-30 15:09:46 +10:00
Rusty Russell a007a751d9 lguest: make Launcher see device status updates
This brings us closer to Real Life, where we'd examine the device
features once it's set the DRIVER_OK status bit.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-05-02 21:50:54 +10:00
Rusty Russell cb38fa23c1 virtio: de-structify virtio_block status byte
Ron Minnich points out that a struct containing a char is not always
sizeof(char); simplest to remove the structure to avoid confusion.

Cc: "ron minnich" <rminnich@gmail.com>

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-05-02 21:50:45 +10:00
Rusty Russell a6bd8e1303 lguest: comment documentation update.
Took some cycles to re-read the Lguest Journey end-to-end, fix some
rot and tighten some phrases.

Only comments change.  No new jokes, but a couple of recycled old jokes.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-03-28 11:05:54 +11:00
Rusty Russell e18b094f0f lguest: Don't need comment terminator before disk section.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-03-28 11:05:53 +11:00
Paul Bolle 9b7a448e2b lguest: lguest.txt documentation fix
Mention the config options for the Virtio drivers and move the Virtualization
menu to the toplevel.

Signed-off-by: Paul Bolle <pebolle@tiscali.nl>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-03-28 11:05:52 +11:00
Tim Ansell b488f22d70 lguest: Add puppies which where previously missing.
lguest doesn't have features, it has puppies!

Signed-off-by: Timothy R Ansell <mithro@mithis.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-03-28 11:05:52 +11:00
Paul Bolle 1ef36fa64e lguest: Do not append space to guests kernel command line
The lguest launcher appends a space to the kernel command line (if kernel
arguments are specified on its command line). This space is unneeded. More
importantly, this appended space will make Red Hat's nash script interpreter
(used in a Fedora style initramfs) add an empty argument to init's command
line. This empty argument will make kernel arguments like "init=/bin/bash"
fail (because the shell will try to execute a script with an empty name).
This could be considered a bug in nash, but is easily fixed in the lguest
launcher too.

Signed-off-by: Paul Bolle <pebolle@tiscali.nl>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-03-11 09:35:58 +11:00
Rusty Russell 6e5aa7efb2 virtio: reset function
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, and

3) 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 <rusty@rustcorp.com.au>
2008-02-04 23:50:03 +11:00
Rusty Russell 426e3e0af5 virtio: clarify NO_NOTIFY flag usage
The other side (host) can set the NO_NOTIFY flag as an optimization,
to say "no need to kick me when you add things".  Make it clear that
this is advisory only; especially that we should always notify when
the ring is full.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-02-04 23:50:00 +11:00