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path: root/drivers/virtio/virtio.c
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2017-04-07virtio: allow drivers to validate featuresMichael S. Tsirkin1-0/+6
Some drivers can't support all features in all configurations. At the moment we blindly set FEATURES_OK and later FAILED. Support this better by adding a callback drivers can use to do some early checks. Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2017-02-07virtio_net: refactor freeze/restore logic into virtnet reset logicJohn Fastabend1-19/+23
For XDP we will need to reset the queues to allow for buffer headroom to be configured. In order to do this we need to essentially run the freeze()/restore() code path. Unfortunately the locking requirements between the freeze/restore and reset paths are different however so we can not simply reuse the code. This patch refactors the code path and adds a reset helper routine. Signed-off-by: John Fastabend <john.r.fastabend@intel.com> Acked-by: Jason Wang <jasowang@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-12-07virtio: fix memory leak of virtio ida cache layersSuman Anna1-0/+1
The virtio core uses a static ida named virtio_index_ida for assigning index numbers to virtio devices during registration. The ida core may allocate some internal idr cache layers and an ida bitmap upon any ida allocation, and all these layers are truely freed only upon the ida destruction. The virtio_index_ida is not destroyed at present, leading to a memory leak when using the virtio core as a module and atleast one virtio device is registered and unregistered. Fix this by invoking ida_destroy() in the virtio core module exit. Cc: stable@vger.kernel.org Signed-off-by: Suman Anna <s-anna@ti.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2015-04-15virtio: drop virtio_device_is_legacy_onlyMichael S. Tsirkin1-6/+0
virtio_device_is_legacy_only is now unused, drop it from core. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2015-04-15virtio: balloon might not be a legacy deviceMichael S. Tsirkin1-1/+1
We added transitional device support to balloon driver, so we don't need to black-list it in core anymore. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2015-02-17virtio: don't set VIRTIO_CONFIG_S_DRIVER_OK twice.Rusty Russell1-1/+4
I noticed this with the console device. It's not *wrong*, just a bit weird. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2014-12-11virtio: set VIRTIO_CONFIG_S_FEATURES_OK on restoreMichael S. Tsirkin1-14/+23
virtio 1.0 devices require that drivers set VIRTIO_CONFIG_S_FEATURES_OK after finalizing features. virtio core missed doing this on restore, fix it up. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
2014-12-09virtio: drop legacy_only driver flagMichael S. Tsirkin1-4/+0
legacy_only flag is now unused, drop it from core. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com>
2014-12-09virtio: allow finalize_features to failMichael S. Tsirkin1-7/+14
This will make it easy for transports to validate features and return failure. Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2014-12-09virtio: add API to detect legacy devicesMichael S. Tsirkin1-0/+7
transports need to be able to detect legacy-only devices (ATM balloon only) to use legacy path to drive them. Add a core API to do just that. The implementation just blacklists balloon: not too pretty, but let's not over-engineer. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com>
2014-12-09virtio: make VIRTIO_F_VERSION_1 a transport bitMichael S. Tsirkin1-1/+5
Activate VIRTIO_F_VERSION_1 automatically unless legacy_only is set. Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2014-12-09virtio: add legacy feature table supportMichael S. Tsirkin1-1/+24
virtio-blk has some legacy feature bits that modern drivers must not negotiate, but are needed for old legacy hosts (that e.g. don't support virtio-scsi). Allow a separate legacy feature table for such cases. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
2014-12-09virtio: simplify feature bit handlingMichael S. Tsirkin1-4/+6
Now that we use u64 for bits, we can simply & them together. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Reviewed-by: David Hildenbrand <dahi@linux.vnet.ibm.com> Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
2014-12-09virtio: set FEATURES_OKMichael S. Tsirkin1-7/+22
set FEATURES_OK as per virtio 1.0 spec Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
2014-12-09virtio: add support for 64 bit features.Michael S. Tsirkin1-4/+4
Change u32 to u64, and use BIT_ULL and 1ULL everywhere. Note: transports are unchanged, and only set low 32 bit. This guarantees that no transport sets e.g. VERSION_1 by mistake without proper support. Based on patch by Rusty. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Reviewed-by: David Hildenbrand <dahi@linux.vnet.ibm.com> Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
2014-12-09virtio: use u32, not bitmap for featuresMichael S. Tsirkin1-5/+5
It seemed like a good idea to use bitmap for features in struct virtio_device, but it's actually a pain, and seems to become even more painful when we get more than 32 feature bits. Just change it to a u32 for now. Based on patch by Rusty. Suggested-by: David Hildenbrand <dahi@linux.vnet.ibm.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
2014-10-15virtio: defer config changed notificationsMichael S. Tsirkin1-9/+49
Defer config changed notifications that arrive during probe/scan/freeze/restore. This will allow drivers to set DRIVER_OK earlier, without worrying about racing with config change interrupts. This change will also benefit old hypervisors (before 2009) that send interrupts without checking DRIVER_OK: previously, the callback could race with driver-specific initialization. This will also help simplify drivers. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (cosmetic changes)
2014-10-15virtio-pci: move freeze/restore to virtio coreMichael S. Tsirkin1-0/+54
This is in preparation to extending config changed event handling in core. Wrapping these in an API also seems to make for a cleaner code. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2014-10-15virtio: unify config_changed handlingMichael S. Tsirkin1-0/+9
Replace duplicated code in all transports with a single wrapper in virtio.c. The only functional change is in virtio_mmio.c: if a buggy device sends us an interrupt before driver is set, we previously returned IRQ_NONE, now we return IRQ_HANDLED. As this must not happen in practice, this does not look like a big deal. See also commit 3fff0179e33cd7d0a688dab65700c46ad089e934 virtio-pci: do not oops on config change if driver not loaded. for the original motivation behind the driver check. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2013-10-17virtio: convert bus code to use dev_groupsGreg Kroah-Hartman1-8/+19
The dev_attrs field of struct bus_type is going away soon, dev_groups should be used instead. This converts the virtio bus code to use the correct field. Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: "Michael S. Tsirkin" <mst@redhat.com> Cc: <virtualization@lists.linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-12-20Merge tag 'virtio-next-for-linus' of ↵Linus Torvalds1-17/+13
git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux Pull virtio update from Rusty Russell: "Some nice cleanups, and even a patch my wife did as a "live" demo for Latinoware 2012. There's a slightly non-trivial merge in virtio-net, as we cleaned up the virtio add_buf interface while DaveM accepted the mq virtio-net patches." * tag 'virtio-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux: (27 commits) virtio_console: Add support for remoteproc serial virtio_console: Merge struct buffer_token into struct port_buffer virtio: add drv_to_virtio to make code clearly virtio: use dev_to_virtio wrapper in virtio virtio-mmio: Fix irq parsing in command line parameter virtio_console: Free buffers from out-queue upon close virtio: Convert dev_printk(KERN_<LEVEL> to dev_<level>( virtio_console: Use kmalloc instead of kzalloc virtio_console: Free buffer if splice fails virtio: tools: make it clear that virtqueue_add_buf() no longer returns > 0 virtio: scsi: make it clear that virtqueue_add_buf() no longer returns > 0 virtio: rpmsg: make it clear that virtqueue_add_buf() no longer returns > 0 virtio: net: make it clear that virtqueue_add_buf() no longer returns > 0 virtio: console: make it clear that virtqueue_add_buf() no longer returns > 0 virtio: make virtqueue_add_buf() returning 0 on success, not capacity. virtio: console: don't rely on virtqueue_add_buf() returning capacity. virtio_net: don't rely on virtqueue_add_buf() returning capacity. virtio-net: remove unused skb_vnet_hdr->num_sg field virtio-net: correct capacity math on ring full virtio: move queue_index and num_free fields into core struct virtqueue. ...
2012-12-18virtio: add drv_to_virtio to make code clearlyWanlong Gao1-7/+4
Add drv_to_virtio wrapper to get virtio_driver from device_driver. Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: "Michael S. Tsirkin" <mst@redhat.com> Signed-off-by: Wanlong Gao <gaowanlong@cn.fujitsu.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-12-18virtio: use dev_to_virtio wrapper in virtioWanlong Gao1-10/+9
Use dev_to_virtio wrapper in virtio to make code clearly. Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: "Michael S. Tsirkin" <mst@redhat.com> Signed-off-by: Wanlong Gao <gaowanlong@cn.fujitsu.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-11-09virtio: Don't access index after unregister.Cornelia Huck1-1/+3
Virtio wants to release used indices after the corresponding virtio device has been unregistered. However, virtio does not hold an extra reference, giving up its last reference with device_unregister(), making accessing dev->index afterwards invalid. I actually saw problems when testing my (not-yet-merged) virtio-ccw code: - device_add virtio-net,id=xxx -> creates device virtio<n> with n>0 - device_del xxx -> deletes virtio<n>, but calls ida_simple_remove with an index of 0 - device_add virtio-net,id=xxx -> tries to add virtio0, which is still in use... So let's save the index we want to release before calling device_unregister(). Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com> Acked-by: Sjur Brændeland <sjur.brandeland@stericsson.com> Cc: stable@kernel.org Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-09-28virtio: don't crash when device is buggyMichael S. Tsirkin1-1/+1
Because of a sanity check in virtio_dev_remove, a buggy device can crash kernel. And in case of rproc it's userspace so it's not a good idea. We are unloading a driver so how bad can it be? Be less aggressive in handling this error: if it's a driver bug, warning once should be enough. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-07-20[SCSI] virtio-scsi: Add vdrv->scan for post VIRTIO_CONFIG_S_DRIVER_OK LUN ↵Nicholas Bellinger1-1/+4
scanning This patch changes virtio-scsi to use a new virtio_driver->scan() callback so that scsi_scan_host() can be properly invoked once virtio_dev_probe() has set add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK) to signal active virtio-ring operation, instead of from within virtscsi_probe(). This fixes a bug where SCSI LUN scanning for both virtio-scsi-raw and virtio-scsi/tcm_vhost setups was happening before VIRTIO_CONFIG_S_DRIVER_OK had been set, causing VIRTIO_SCSI_S_BAD_TARGET to occur. This fixes a bug with virtio-scsi/tcm_vhost where LUN scan was not detecting LUNs. Tested with virtio-scsi-raw + virtio-scsi/tcm_vhost w/ IBLOCK on 3.5-rc2 code. Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org> Acked-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: James Bottomley <JBottomley@Parallels.com>
2012-05-22virtio: Use ida to allocate virtio indexAsias He1-2/+9
Current index allocation in virtio is based on a monotonically increasing variable "index". This means we'll run out of numbers after a while. E.g. someone crazy doing this in host side. while(1) { hot-plug a virtio device hot-unplug the virito devcie } Signed-off-by: Asias He <asias@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2011-11-01virtio: Add module.h to drivers/virtio users.Paul Gortmaker1-0/+1
Up to now, the module.h header was as hard to keep out as sunlight. But we are cleaning that up. Fix the virtio users who simply expect module.h to be there in every C file. Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
2010-11-24virtio: fix format of sysfs driver/vendor filesStephen Hemminger1-3/+3
The sysfs files for virtio produce the wrong format and are missing the required newline. The output for virtio bus vendor/device should have the same format as the corresponding entries for PCI devices. Although this technically changes the ABI for sysfs, these files were broken to start with! Signed-off-by: Stephen Hemminger <shemminger@vyatta.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2009-06-12virtio: enhance id_matching for virtio driversChristian Borntraeger1-1/+1
This patch allows a virtio driver to use VIRTIO_DEV_ANY_ID for the device id. This will be used by a test module that can be bound to any virtio device. Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2009-06-12virtio: fix id_matching for virtio driversChristian Borntraeger1-1/+1
This bug never appeared, since all current virtio drivers use VIRTIO_DEV_ANY_ID for the vendor field. If a real vendor would be used, the check in virtio_id_match is wrong - it returns 0 if id->vendor == dev->id.vendor. Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2009-06-12virtio: expose features in sysfsRusty Russell1-0/+16
Each device negotiates feature bits; expose these in sysfs to help diagnostics and debugging. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2009-06-12virtio: add names to virtqueue struct, mapping from devices to queues.Rusty Russell1-0/+2
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 <rusty@rustcorp.com.au>
2009-06-12virtio: meet virtio spec by finalizing features before using deviceRusty Russell1-3/+4
Virtio devices are supposed to negotiate features before they start using the device, but the current code doesn't do this. This is because the driver's probe() function invariably has to add buffers to a virtqueue, or probe the disk (virtio_blk). This currently doesn't matter since no existing backend is strict about the feature negotiation. But it's possible to imagine a future feature which completely changes how a device operates: in this case, we'd need to acknowledge it before using the device. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-12-30virtio: struct device - replace bus_id with dev_name(), dev_set_name()Kay Sievers1-1/+1
This patch is part of a larger patch series which will remove the "char bus_id[20]" name string from struct device. The device name is managed in the kobject anyway, and without any size limitation, and just needlessly copied into "struct device". To set and read the device name dev_name(dev) and dev_set_name(dev) must be used. If your code uses static kobjects, which it shouldn't do, "const char *init_name" can be used to statically provide the name the registered device should have. At registration time, the init_name field is cleared, to enforce the use of dev_name(dev) to access the device name at a later time. We need to get rid of all occurrences of bus_id in the entire tree to be able to enable the new interface. Please apply this patch, and possibly convert any remaining remaining occurrences of bus_id. We want to submit a patch to -next, which will remove bus_id from "struct device", to find the remaining pieces to convert, and finally switch over to the new api, which will remove the 20 bytes array and does no longer have a size limitation. Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Kay Sievers <kay.sievers@vrfy.org> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-07-25virtio: Rename set_features to finalize_featuresRusty Russell1-3/+2
Rather than explicitly handing the features to the lower-level, we just hand the virtio_device and have it set the features. This make it clear that it has the chance to manipulate the features of the device at this point (and that all feature negotiation is already done). Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-07-25virtio: Formally reserve bits 28-31 to be 'transport' features.Rusty Russell1-0/+5
We assign feature bits as required, but it makes sense to reserve some for the particular transport, rather than the particular device. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-07-25virtio: Use bus_type probe and remove methodsMark McLoughlin1-9/+9
Hook up to the probe() and remove() methods in bus_type rather than device_driver. The latter has been preferred since 2.6.16. Signed-off-by: Mark McLoughlin <markmc@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-06-16virtio: Complete feature negotation before updating statusMark McLoughlin1-1/+1
lguest (in rusty's use-tun-ringfd patch) assumes that the guest has updated its feature bits before setting its status to VIRTIO_CONFIG_S_DRIVER_OK. That's pretty reasonable, so let's make it so. Signed-off-by: Mark McLoughlin <markmc@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-05-30virtio: set device index in common code.Rusty Russell1-0/+6
Anthony Liguori points out that three different transports use the virtio code, but each one keeps its own counter to set the virtio_device's index field. In theory (though not in current practice) this means that names could be duplicated, and that risk grows as more transports are created. So we move the selection of the unique virtio_device.index into the common code in virtio.c, which has the side-benefit of removing duplicate code. The only complexity is that lguest and S/390 use the index to uniquely identify the device in case of catastrophic failure before register_virtio_device() is called: now we use the offset within the descriptor page as a unique identifier for the printks. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Carsten Otte <cotte@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Chris Lalancette <clalance@redhat.com> Cc: Anthony Liguori <anthony@codemonkey.ws>
2008-05-30virtio: bus_id for devices should contain 'virtio'Rusty Russell1-1/+1
Chris Lalancette <clalance@redhat.com> points out that virtio.c sets all device names to '0', '1', etc, which looks silly in /proc/interrupts. We change this from '%d' to 'virtio%d'. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Carsten Otte <cotte@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Chris Lalancette <clalance@redhat.com> Cc: Anthony Liguori <anthony@codemonkey.ws>
2008-05-02virtio: explicit advertisement of driver featuresRusty Russell1-2/+36
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 bits Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-02-04virtio: Allow virtio to be modular and used by modulesRusty Russell1-0/+8
This is needed for the virtio PCI device to be compiled as a module. Signed-off-by: Anthony Liguori <aliguori@us.ibm.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-02-04virtio: reset functionRusty Russell1-2/+10
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>
2008-02-04virtio: simplify config mechanism.Rusty Russell1-45/+0
Previously we used a type/len pair within the config space, but this seems overkill. We now simply define a structure which represents the layout in the config space: the config space can now only be extended at the end. The main driver-visible changes: 1) We indicate what fields are present with an explicit feature bit. 2) Virtqueues are explicitly numbered, and not in the config space. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2007-11-19virtio: fix module/device unloadingRusty Russell1-0/+13
The virtio code never hooked through the ->remove callback. Although noone supports device removal at the moment, this code is already needed for module unloading. This of course also revealed bugs in virtio_blk, virtio_net and lguest unloading paths. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2007-10-23Module autoprobing support for virtio drivers.Rusty Russell1-0/+18
This adds the logic to convert the virtio ids into module aliases, and includes a modalias entry in sysfs and the env var to make probing work. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2007-10-23Virtio interfaceRusty Russell1-0/+171
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 <rusty@rustcorp.com.au> Cc: Dor Laor <dor.laor@qumranet.com> Cc: Arnd Bergmann <arnd@arndb.de>