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Currently a host kick error is silently ignored and not reflected in
the virtqueue of a particular virtio device.
Changing the notify API for guest->host notification seems to be one
prerequisite in order to be able to handle such errors in the context
where the kick is triggered.
This patch changes the notify API. The notify function must return a
bool return value. It returns false if the host notification failed.
Signed-off-by: Heinz Graalfs <[email protected]>
Signed-off-by: Rusty Russell <[email protected]>
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virtio_ring.h uses mb() and friends, make
it pull in asm/barrier.h itself, not rely
on other headers to do it.
Signed-off-by: Michael S. Tsirkin <[email protected]>
Signed-off-by: Rusty Russell <[email protected]>
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The host side of ring needs this logic too.
Signed-off-by: Rusty Russell <[email protected]>
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Signed-off-by: David Howells <[email protected]>
Acked-by: Arnd Bergmann <[email protected]>
Acked-by: Thomas Gleixner <[email protected]>
Acked-by: Michael Kerrisk <[email protected]>
Acked-by: Paul E. McKenney <[email protected]>
Acked-by: Dave Jones <[email protected]>
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Instead of storing the queue index in transport-specific virtio structs,
this patch moves them to vring_virtqueue and introduces an helper to get
the value. This lets drivers simplify their management and tracing of
virtqueues.
Signed-off-by: Jason Wang <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
Signed-off-by: Rusty Russell <[email protected]>
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We were cheating with our barriers; using the smp ones rather than the
real device ones. That was fine, until rpmsg came along, which is
used to talk to a real device (a non-SMP CPU).
Unfortunately, just putting back the real barriers (reverting
d57ed95d) causes a performance regression on virtio-pci. In
particular, Amos reports netbench's TCP_RR over virtio_net CPU
utilization increased up to 35% while throughput went down by up to
14%.
By comparison, this branch is in the noise.
Reference: https://lkml.org/lkml/2011/12/11/22
Signed-off-by: Rusty Russell <[email protected]>
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containing *_event_idx
Based on the layout description in the comments, take account of
the *_event_idx in functions vring_init and vring_size.
Signed-off-by: Wang Sheng-Hui <[email protected]>
Signed-off-by: Rusty Russell <[email protected]>
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With the new used_event and avail_event and features, both
host and guest need similar logic to check whether events are
enabled, so it helps to put the common code in the header.
Note that Xen has similar logic for notification hold-off
in include/xen/interface/io/ring.h with req_event and req_prod
corresponding to event_idx + 1 and new_idx respectively.
+1 comes from the fact that req_event and req_prod in Xen start at 1,
while event index in virtio starts at 0.
Signed-off-by: Michael S. Tsirkin <[email protected]>
Signed-off-by: Rusty Russell <[email protected]>
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Define a new feature bit for the guest and host to utilize
an event index (like Xen) instead if a flag bit to enable/disable
interrupts and kicks.
Signed-off-by: Michael S. Tsirkin <[email protected]>
Signed-off-by: Rusty Russell <[email protected]>
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It's unclear to me if it's important, but it's obviously causing my
technical colleages some headaches and I'd hate such imprecision to
slow virtio adoption.
I've emailed this to all non-trivial contributors for approval, too.
Signed-off-by: Rusty Russell <[email protected]>
Acked-by: Grant Likely <[email protected]>
Acked-by: Ryan Harper <[email protected]>
Acked-by: Anthony Liguori <[email protected]>
Acked-by: Eric Van Hensbergen <[email protected]>
Acked-by: john cooper <[email protected]>
Acked-by: Aneesh Kumar K.V <[email protected]>
Acked-by: Christian Borntraeger <[email protected]>
Acked-by: Fernando Luis Vazquez Cao <[email protected]>
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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 <[email protected]>
Cc: Ingo Molnar <[email protected]>
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Add a new feature flag for indirect ring entries. These are ring
entries which point to a table of buffer descriptors.
The idea here is to increase the ring capacity by allowing a larger
effective ring size whereby the ring size dictates the number of
requests that may be outstanding, rather than the size of those
requests.
This should be most effective in the case of block I/O where we can
potentially benefit by concurrently dispatching a large number of
large requests. Even in the simple case of single segment block
requests, this results in a threefold increase in ring capacity.
Signed-off-by: Mark McLoughlin <[email protected]>
Signed-off-by: Rusty Russell <[email protected]>
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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 <[email protected]>
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This allows each virtio user to hand in the alignment appropriate to
their virtio_ring structures.
Signed-off-by: Rusty Russell <[email protected]>
Acked-by: Christian Borntraeger <[email protected]>
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It's really the alignment desired for consumer/producer separation;
historically this x86 pagesize, but with PowerPC it'll still be x86
pagesize. And in theory lguest could choose a different value.
Signed-off-by: Rusty Russell <[email protected]>
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To prepare for virtio_ring transport feature bits, hook in a call in
all the users to manipulate them. This currently just clears all the
bits, since it doesn't understand any features.
Signed-off-by: Rusty Russell <[email protected]>
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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 <[email protected]>
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Using unsigned int resulted in silent truncation of the upper 32-bit
on x86_64 resulting in an OOPS since the ring was being initialized
wrong.
Please reconsider my previous patch to just use PAGE_ALIGN(). Open
coding this sort of stuff, no matter how simple it seems, is just
asking for this sort of trouble.
Signed-off-by: Anthony Liguori <[email protected]>
Signed-off-by: Rusty Russell <[email protected]>
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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 <[email protected]>
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The virtio descriptor rings of size N-1 were nicely set up to be
aligned to an N-byte boundary. But as Anthony Liguori points out, the
free-running indices used by virtio require that the sizes be a power
of 2, otherwise we get problems on wrap (demonstrated with lguest).
So we replace the clever "2^n-1" scheme with a simple "align to page
boundary" scheme: this means that all virtio rings take at least two
pages, but it's safer than guessing cache alignment.
Signed-off-by: Rusty Russell <[email protected]>
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This patch fixes a typo in vring_init(). This happens to work today in lguest
because the sizeof(struct vring_desc) is 16 and struct vring contains 3
pointers and an unsigned int so on 32-bit
sizeof(struct vring_desc) == sizeof(struct vring). However, this is no longer
true on 64-bit where the bug is exposed.
Signed-off-by: Anthony Liguori <[email protected]>
Signed-off-by: Rusty Russell <[email protected]>
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These helper routines supply most of the virtqueue_ops for hypervisors
which want to use a ring for virtio. Unlike the previous lguest
implementation:
1) The rings are variable sized (2^n-1 elements).
2) They have an unfortunate limit of 65535 bytes per sg element.
3) The page numbers are always 64 bit (PAE anyone?)
4) They no longer place used[] on a separate page, just a separate
cacheline.
5) We do a modulo on a variable. We could be tricky if we cared.
6) Interrupts and notifies are suppressed using flags within the rings.
Users need only get the ring pages and provide a notify hook (KVM
wants the guest to allocate the rings, lguest does it sanely).
Signed-off-by: Rusty Russell <[email protected]>
Cc: Dor Laor <[email protected]>
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