virtio: Virtio platform driver
[PATCH 01/02] virtio: Break out lguest virtio code to virtio_lguest.c
[PATCH 02/02] virtio: Add virtio platform driver
These patches add a virtio platform driver to the Linux kernel. This
platform driver has the same role as the virtio_pci driver, but instead
of building on top of emulated PCI this driver is making use of the
platform bus together with driver specific callbacks.
The virtio platform driver can be seen as a reusable implementation of
the lguest virtio driver - in fact, most code is just taken directly
from lguest_device.c and reworked to fit the platform device driver
abstraction. The first patch breaks out code that can be shared between
lguest and the virtio platform driver.
This code has been used to implement a mailbox interface between the
two processor cores included in the sh7372 SoC. The sh7372 contains
one ARM Cortex-A8 and one SH4AL-DSP core, and in the prototype two
Linux kernels are running in parallel on the same chip. Virtio serves
as a communication link between the two cores.
These patches have not been updated since last time they were posted
20110310, but are known to apply and compile against linux-3.0-rc.
For a full source release, have a look at SH Core Linux 20110317:
http://www.spinics.net/lists/linux-sh/msg07188.html
The SH kernel patch shows how to make use of the virtio platform driver.
Signed-off-by: Magnus Damm <[email protected]>
---
arch/x86/lguest/Kconfig | 1
drivers/lguest/lguest_device.c | 209 ----------------------------
drivers/virtio/Kconfig | 13 +
drivers/virtio/Makefile | 2
drivers/virtio/virtio_lguest.c | 205 ++++++++++++++++++++++++++++
drivers/virtio/virtio_platform.c | 282 +++++++++++++++++++++++++++++++++++++++
include/linux/lguest.h | 1
include/linux/lguest_device.h | 46 ++++++
include/linux/virtio_platform.h | 12 +
9 files changed, 564 insertions(+), 207 deletions(-)
From: Magnus Damm <[email protected]>
This patch breaks out code from lguest_device.c to the new file
virtio_lguest.c. The new file is built when CONFIG_VIRTIO_LGUEST
is selected. The x86 architecture is updated to select this kconfig
variable in the case of lguest.
Needed by the virtio platform driver that shares configuration data
structures with lguest.
Signed-off-by: Magnus Damm <[email protected]>
---
arch/x86/lguest/Kconfig | 1
drivers/lguest/lguest_device.c | 209 ----------------------------------------
drivers/virtio/Kconfig | 2
drivers/virtio/Makefile | 1
drivers/virtio/virtio_lguest.c | 205 +++++++++++++++++++++++++++++++++++++++
include/linux/lguest.h | 1
include/linux/lguest_device.h | 46 ++++++++
7 files changed, 258 insertions(+), 207 deletions(-)
--- 0001/arch/x86/lguest/Kconfig
+++ work/arch/x86/lguest/Kconfig 2011-03-03 10:16:11.000000000 +0900
@@ -4,6 +4,7 @@ config LGUEST_GUEST
depends on X86_32
select VIRTUALIZATION
select VIRTIO
+ select VIRTIO_LGUEST
select VIRTIO_RING
select VIRTIO_CONSOLE
help
--- 0001/drivers/lguest/lguest_device.c
+++ work/drivers/lguest/lguest_device.c 2011-03-03 10:16:11.000000000 +0900
@@ -14,6 +14,7 @@
#include <linux/virtio_config.h>
#include <linux/interrupt.h>
#include <linux/virtio_ring.h>
+#include <linux/lguest_device.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <asm/io.h>
@@ -37,137 +38,6 @@ static inline void lguest_unmap(void *ad
iounmap((__force void __iomem *)addr);
}
-/*D:100
- * Each lguest device is just a virtio device plus a pointer to its entry
- * in the lguest_devices page.
- */
-struct lguest_device {
- struct virtio_device vdev;
-
- /* The entry in the lguest_devices page for this device. */
- struct lguest_device_desc *desc;
-};
-
-/*
- * Since the virtio infrastructure hands us a pointer to the virtio_device all
- * the time, it helps to have a curt macro to get a pointer to the struct
- * lguest_device it's enclosed in.
- */
-#define to_lgdev(vd) container_of(vd, struct lguest_device, vdev)
-
-/*D:130
- * Device configurations
- *
- * The configuration information for a device consists of one or more
- * virtqueues, a feature bitmap, and some configuration bytes. The
- * configuration bytes don't really matter to us: the Launcher sets them up, and
- * the driver will look at them during setup.
- *
- * A convenient routine to return the device's virtqueue config array:
- * immediately after the descriptor.
- */
-static struct lguest_vqconfig *lg_vq(const struct lguest_device_desc *desc)
-{
- return (void *)(desc + 1);
-}
-
-/* The features come immediately after the virtqueues. */
-static u8 *lg_features(const struct lguest_device_desc *desc)
-{
- return (void *)(lg_vq(desc) + desc->num_vq);
-}
-
-/* The config space comes after the two feature bitmasks. */
-static u8 *lg_config(const struct lguest_device_desc *desc)
-{
- return lg_features(desc) + desc->feature_len * 2;
-}
-
-/* The total size of the config page used by this device (incl. desc) */
-static unsigned desc_size(const struct lguest_device_desc *desc)
-{
- return sizeof(*desc)
- + desc->num_vq * sizeof(struct lguest_vqconfig)
- + desc->feature_len * 2
- + desc->config_len;
-}
-
-/* This gets the device's feature bits. */
-static u32 lg_get_features(struct virtio_device *vdev)
-{
- unsigned int i;
- u32 features = 0;
- struct lguest_device_desc *desc = to_lgdev(vdev)->desc;
- u8 *in_features = lg_features(desc);
-
- /* We do this the slow but generic way. */
- for (i = 0; i < min(desc->feature_len * 8, 32); i++)
- if (in_features[i / 8] & (1 << (i % 8)))
- features |= (1 << i);
-
- return features;
-}
-
-/*
- * The virtio core takes the features the Host offers, and copies the ones
- * supported by the driver into the vdev->features array. Once that's all
- * sorted out, this routine is called so we can tell the Host which features we
- * understand and accept.
- */
-static void lg_finalize_features(struct virtio_device *vdev)
-{
- unsigned int i, bits;
- struct lguest_device_desc *desc = to_lgdev(vdev)->desc;
- /* Second half of bitmap is features we accept. */
- u8 *out_features = lg_features(desc) + desc->feature_len;
-
- /* Give virtio_ring a chance to accept features. */
- vring_transport_features(vdev);
-
- /*
- * The vdev->feature array is a Linux bitmask: this isn't the same as a
- * the simple array of bits used by lguest devices for features. So we
- * do this slow, manual conversion which is completely general.
- */
- memset(out_features, 0, desc->feature_len);
- bits = min_t(unsigned, desc->feature_len, sizeof(vdev->features)) * 8;
- for (i = 0; i < bits; i++) {
- if (test_bit(i, vdev->features))
- out_features[i / 8] |= (1 << (i % 8));
- }
-}
-
-/* Once they've found a field, getting a copy of it is easy. */
-static void lg_get(struct virtio_device *vdev, unsigned int offset,
- void *buf, unsigned len)
-{
- struct lguest_device_desc *desc = to_lgdev(vdev)->desc;
-
- /* Check they didn't ask for more than the length of the config! */
- BUG_ON(offset + len > desc->config_len);
- memcpy(buf, lg_config(desc) + offset, len);
-}
-
-/* Setting the contents is also trivial. */
-static void lg_set(struct virtio_device *vdev, unsigned int offset,
- const void *buf, unsigned len)
-{
- struct lguest_device_desc *desc = to_lgdev(vdev)->desc;
-
- /* Check they didn't ask for more than the length of the config! */
- BUG_ON(offset + len > desc->config_len);
- memcpy(lg_config(desc) + offset, buf, len);
-}
-
-/*
- * The operations to get and set the status word just access the status field
- * of the device descriptor.
- */
-static u8 lg_get_status(struct virtio_device *vdev)
-{
- return to_lgdev(vdev)->desc->status;
-}
-
/*
* To notify on status updates, we (ab)use the NOTIFY hypercall, with the
* descriptor address of the device. A zero status means "reset".
@@ -392,81 +262,6 @@ static struct virtio_config_ops lguest_c
*/
static struct device *lguest_root;
-/*D:120
- * This is the core of the lguest bus: actually adding a new device.
- * It's a separate function because it's neater that way, and because an
- * earlier version of the code supported hotplug and unplug. They were removed
- * early on because they were never used.
- *
- * As Andrew Tridgell says, "Untested code is buggy code".
- *
- * It's worth reading this carefully: we start with a pointer to the new device
- * descriptor in the "lguest_devices" page, and the offset into the device
- * descriptor page so we can uniquely identify it if things go badly wrong.
- */
-static void add_lguest_device(struct lguest_device_desc *d,
- unsigned int offset)
-{
- struct lguest_device *ldev;
-
- /* Start with zeroed memory; Linux's device layer counts on it. */
- ldev = kzalloc(sizeof(*ldev), GFP_KERNEL);
- if (!ldev) {
- printk(KERN_EMERG "Cannot allocate lguest dev %u type %u\n",
- offset, d->type);
- return;
- }
-
- /* This devices' parent is the lguest/ dir. */
- ldev->vdev.dev.parent = lguest_root;
- /*
- * The device type comes straight from the descriptor. There's also a
- * device vendor field in the virtio_device struct, which we leave as
- * 0.
- */
- ldev->vdev.id.device = d->type;
- /*
- * We have a simple set of routines for querying the device's
- * configuration information and setting its status.
- */
- ldev->vdev.config = &lguest_config_ops;
- /* And we remember the device's descriptor for lguest_config_ops. */
- ldev->desc = d;
-
- /*
- * register_virtio_device() sets up the generic fields for the struct
- * virtio_device and calls device_register(). This makes the bus
- * infrastructure look for a matching driver.
- */
- if (register_virtio_device(&ldev->vdev) != 0) {
- printk(KERN_ERR "Failed to register lguest dev %u type %u\n",
- offset, d->type);
- kfree(ldev);
- }
-}
-
-/*D:110
- * scan_devices() simply iterates through the device page. The type 0 is
- * reserved to mean "end of devices".
- */
-static void scan_devices(void)
-{
- unsigned int i;
- struct lguest_device_desc *d;
-
- /* We start at the page beginning, and skip over each entry. */
- for (i = 0; i < PAGE_SIZE; i += desc_size(d)) {
- d = lguest_devices + i;
-
- /* Once we hit a zero, stop. */
- if (d->type == 0)
- break;
-
- printk("Device at %i has size %u\n", i, desc_size(d));
- add_lguest_device(d, i);
- }
-}
-
/*D:105
* Fairly early in boot, lguest_devices_init() is called to set up the
* lguest device infrastructure. We check that we are a Guest by checking
@@ -493,7 +288,7 @@ static int __init lguest_devices_init(vo
/* Devices are in a single page above top of "normal" mem */
lguest_devices = lguest_map(max_pfn<<PAGE_SHIFT, 1);
- scan_devices();
+ lg_scan_devices(lguest_devices, lguest_root, &lguest_config_ops);
return 0;
}
/* We do this after core stuff, but before the drivers. */
--- 0001/drivers/virtio/Kconfig
+++ work/drivers/virtio/Kconfig 2011-03-03 10:16:11.000000000 +0900
@@ -33,3 +33,5 @@ config VIRTIO_BALLOON
If unsure, say M.
+config VIRTIO_LGUEST
+ tristate
--- 0001/drivers/virtio/Makefile
+++ work/drivers/virtio/Makefile 2011-03-03 10:16:11.000000000 +0900
@@ -2,3 +2,4 @@ obj-$(CONFIG_VIRTIO) += virtio.o
obj-$(CONFIG_VIRTIO_RING) += virtio_ring.o
obj-$(CONFIG_VIRTIO_PCI) += virtio_pci.o
obj-$(CONFIG_VIRTIO_BALLOON) += virtio_balloon.o
+obj-$(CONFIG_VIRTIO_LGUEST) += virtio_lguest.o
--- /dev/null
+++ work/drivers/virtio/virtio_lguest.c 2011-03-03 10:16:12.000000000 +0900
@@ -0,0 +1,205 @@
+/*P:050
+ * Lguest guests use a very simple method to describe devices. It's a
+ * series of device descriptors contained just above the top of normal Guest
+ * memory.
+ *
+ * We use the standard "virtio" device infrastructure, which provides us with a
+ * console, a network and a block driver. Each one expects some configuration
+ * information and a "virtqueue" or two to send and receive data.
+:*/
+#include <linux/init.h>
+#include <linux/bootmem.h>
+#include <linux/lguest_launcher.h>
+#include <linux/virtio.h>
+#include <linux/virtio_config.h>
+#include <linux/interrupt.h>
+#include <linux/virtio_ring.h>
+#include <linux/lguest_device.h>
+#include <linux/err.h>
+#include <linux/slab.h>
+#include <asm/io.h>
+
+/*D:130
+ * Device configurations
+ *
+ * The configuration information for a device consists of one or more
+ * virtqueues, a feature bitmap, and some configuration bytes. The
+ * configuration bytes don't really matter to us: the Launcher sets them up, and
+ * the driver will look at them during setup.
+ */
+
+/* The features come immediately after the virtqueues. */
+static u8 *lg_features(const struct lguest_device_desc *desc)
+{
+ return (void *)(lg_vq(desc) + desc->num_vq);
+}
+
+/* The config space comes after the two feature bitmasks. */
+static u8 *lg_config(const struct lguest_device_desc *desc)
+{
+ return lg_features(desc) + desc->feature_len * 2;
+}
+
+/* The total size of the config page used by this device (incl. desc) */
+static unsigned desc_size(const struct lguest_device_desc *desc)
+{
+ return sizeof(*desc)
+ + desc->num_vq * sizeof(struct lguest_vqconfig)
+ + desc->feature_len * 2
+ + desc->config_len;
+}
+
+/* This gets the device's feature bits. */
+u32 lg_get_features(struct virtio_device *vdev)
+{
+ unsigned int i;
+ u32 features = 0;
+ struct lguest_device_desc *desc = to_lgdev(vdev)->desc;
+ u8 *in_features = lg_features(desc);
+
+ /* We do this the slow but generic way. */
+ for (i = 0; i < min(desc->feature_len * 8, 32); i++)
+ if (in_features[i / 8] & (1 << (i % 8)))
+ features |= (1 << i);
+
+ return features;
+}
+
+/*
+ * The virtio core takes the features the Host offers, and copies the ones
+ * supported by the driver into the vdev->features array. Once that's all
+ * sorted out, this routine is called so we can tell the Host which features we
+ * understand and accept.
+ */
+void lg_finalize_features(struct virtio_device *vdev)
+{
+ unsigned int i, bits;
+ struct lguest_device_desc *desc = to_lgdev(vdev)->desc;
+ /* Second half of bitmap is features we accept. */
+ u8 *out_features = lg_features(desc) + desc->feature_len;
+
+ /* Give virtio_ring a chance to accept features. */
+ vring_transport_features(vdev);
+
+ /*
+ * The vdev->feature array is a Linux bitmask: this isn't the same as a
+ * the simple array of bits used by lguest devices for features. So we
+ * do this slow, manual conversion which is completely general.
+ */
+ memset(out_features, 0, desc->feature_len);
+ bits = min_t(unsigned, desc->feature_len, sizeof(vdev->features)) * 8;
+ for (i = 0; i < bits; i++) {
+ if (test_bit(i, vdev->features))
+ out_features[i / 8] |= (1 << (i % 8));
+ }
+}
+
+/* Once they've found a field, getting a copy of it is easy. */
+void lg_get(struct virtio_device *vdev, unsigned int offset,
+ void *buf, unsigned len)
+{
+ struct lguest_device_desc *desc = to_lgdev(vdev)->desc;
+
+ /* Check they didn't ask for more than the length of the config! */
+ BUG_ON(offset + len > desc->config_len);
+ memcpy(buf, lg_config(desc) + offset, len);
+}
+
+/* Setting the contents is also trivial. */
+void lg_set(struct virtio_device *vdev, unsigned int offset,
+ const void *buf, unsigned len)
+{
+ struct lguest_device_desc *desc = to_lgdev(vdev)->desc;
+
+ /* Check they didn't ask for more than the length of the config! */
+ BUG_ON(offset + len > desc->config_len);
+ memcpy(lg_config(desc) + offset, buf, len);
+}
+
+/*
+ * The operations to get and set the status word just access the status field
+ * of the device descriptor.
+ */
+u8 lg_get_status(struct virtio_device *vdev)
+{
+ return to_lgdev(vdev)->desc->status;
+}
+
+/*D:120
+ * This is the core of the lguest bus: actually adding a new device.
+ * It's a separate function because it's neater that way, and because an
+ * earlier version of the code supported hotplug and unplug. They were removed
+ * early on because they were never used.
+ *
+ * As Andrew Tridgell says, "Untested code is buggy code".
+ *
+ * It's worth reading this carefully: we start with a pointer to the new device
+ * descriptor in the "lguest_devices" page, and the offset into the device
+ * descriptor page so we can uniquely identify it if things go badly wrong.
+ */
+static void add_lguest_device(struct lguest_device_desc *d,
+ unsigned int offset,
+ struct device *root,
+ struct virtio_config_ops *ops)
+{
+ struct lguest_device *ldev;
+
+ /* Start with zeroed memory; Linux's device layer counts on it. */
+ ldev = kzalloc(sizeof(*ldev), GFP_KERNEL);
+ if (!ldev) {
+ printk(KERN_EMERG "Cannot allocate lguest dev %u type %u\n",
+ offset, d->type);
+ return;
+ }
+
+ /* This devices' parent is the lguest/ dir. */
+ ldev->vdev.dev.parent = root;
+ /*
+ * The device type comes straight from the descriptor. There's also a
+ * device vendor field in the virtio_device struct, which we leave as
+ * 0.
+ */
+ ldev->vdev.id.device = d->type;
+ /*
+ * We have a simple set of routines for querying the device's
+ * configuration information and setting its status.
+ */
+ ldev->vdev.config = ops;
+ /* And we remember the device's descriptor. */
+ ldev->desc = d;
+
+ /*
+ * register_virtio_device() sets up the generic fields for the struct
+ * virtio_device and calls device_register(). This makes the bus
+ * infrastructure look for a matching driver.
+ */
+ if (register_virtio_device(&ldev->vdev) != 0) {
+ printk(KERN_ERR "Failed to register lguest dev %u type %u\n",
+ offset, d->type);
+ kfree(ldev);
+ }
+}
+
+/*D:110
+ * lg_scan_devices() simply iterates through the device page. The type 0 is
+ * reserved to mean "end of devices".
+ */
+void lg_scan_devices(void *lguest_devices,
+ struct device *root,
+ struct virtio_config_ops *ops)
+{
+ unsigned int i;
+ struct lguest_device_desc *d;
+
+ /* We start at the page beginning, and skip over each entry. */
+ for (i = 0; i < PAGE_SIZE; i += desc_size(d)) {
+ d = lguest_devices + i;
+
+ /* Once we hit a zero, stop. */
+ if (d->type == 0)
+ break;
+
+ printk("Device at %i has size %u\n", i, desc_size(d));
+ add_lguest_device(d, i, root, ops);
+ }
+}
--- 0001/include/linux/lguest.h
+++ work/include/linux/lguest.h 2011-03-03 10:16:11.000000000 +0900
@@ -71,5 +71,6 @@ struct lguest_data {
unsigned int syscall_vec;
};
extern struct lguest_data lguest_data;
+
#endif /* __ASSEMBLY__ */
#endif /* _LINUX_LGUEST_H */
--- /dev/null
+++ work/include/linux/lguest_device.h 2011-03-03 16:07:51.000000000 +0900
@@ -0,0 +1,46 @@
+#ifndef _LINUX_LGUEST_DEVICE_H
+#define _LINUX_LGUEST_DEVICE_H
+
+#include <linux/virtio.h>
+#include <linux/lguest_launcher.h>
+
+/*D:100
+ * Each lguest device is just a virtio device plus a pointer to its entry
+ * in the lguest_devices page.
+ */
+struct lguest_device {
+ struct virtio_device vdev;
+
+ /* The entry in the lguest_devices page for this device. */
+ struct lguest_device_desc *desc;
+};
+
+u32 lg_get_features(struct virtio_device *vdev);
+void lg_finalize_features(struct virtio_device *vdev);
+void lg_get(struct virtio_device *vdev, unsigned int offset,
+ void *buf, unsigned len);
+void lg_set(struct virtio_device *vdev, unsigned int offset,
+ const void *buf, unsigned len);
+u8 lg_get_status(struct virtio_device *vdev);
+void lg_scan_devices(void *lguest_devices,
+ struct device *root,
+ struct virtio_config_ops *ops);
+
+/*
+ * A convenient routine to return the device's virtqueue config array:
+ * immediately after the descriptor.
+ */
+static inline struct lguest_vqconfig *
+lg_vq(const struct lguest_device_desc *desc)
+{
+ return (void *)(desc + 1);
+}
+
+/*
+ * Since the virtio infrastructure hands us a pointer to the virtio_device all
+ * the time, it helps to have a curt macro to get a pointer to the struct
+ * lguest_device it's enclosed in.
+ */
+#define to_lgdev(vd) container_of(vd, struct lguest_device, vdev)
+
+#endif /* _LINUX_LGUEST_DEVICE_H */
From: Magnus Damm <[email protected]>
This patch adds a virtio platform driver. The code is based on
the lguest implementation available in drivers/lguest/lguest_device.c
The iomem resource is used to point out the lguest device descriptor,
and the platform data contains two separate callbacks for notification.
Signed-off-by: Magnus Damm <[email protected]>
---
drivers/virtio/Kconfig | 11 +
drivers/virtio/Makefile | 1
drivers/virtio/virtio_platform.c | 282 ++++++++++++++++++++++++++++++++++++++
include/linux/virtio_platform.h | 12 +
4 files changed, 306 insertions(+)
--- 0002/drivers/virtio/Kconfig
+++ work/drivers/virtio/Kconfig 2011-03-03 15:56:53.000000000 +0900
@@ -35,3 +35,14 @@ config VIRTIO_BALLOON
config VIRTIO_LGUEST
tristate
+
+config VIRTIO_PLATFORM
+ tristate "Platform driver for virtio devices (EXPERIMENTAL)"
+ select VIRTIO
+ select VIRTIO_RING
+ select VIRTIO_LGUEST
+ ---help---
+ This drivers provides support for virtio based paravirtual device
+ drivers over a platform bus.
+
+ If unsure, say N.
--- 0002/drivers/virtio/Makefile
+++ work/drivers/virtio/Makefile 2011-03-03 15:56:53.000000000 +0900
@@ -3,3 +3,4 @@ obj-$(CONFIG_VIRTIO_RING) += virtio_ring
obj-$(CONFIG_VIRTIO_PCI) += virtio_pci.o
obj-$(CONFIG_VIRTIO_BALLOON) += virtio_balloon.o
obj-$(CONFIG_VIRTIO_LGUEST) += virtio_lguest.o
+obj-$(CONFIG_VIRTIO_PLATFORM) += virtio_platform.o
--- /dev/null
+++ work/drivers/virtio/virtio_platform.c 2011-03-03 16:07:31.000000000 +0900
@@ -0,0 +1,282 @@
+#include <linux/init.h>
+#include <linux/virtio.h>
+#include <linux/virtio_config.h>
+#include <linux/virtio_ring.h>
+#include <linux/lguest_device.h>
+#include <linux/lguest_launcher.h>
+#include <linux/virtio_platform.h>
+#include <linux/platform_device.h>
+#include <linux/interrupt.h>
+#include <linux/err.h>
+#include <linux/slab.h>
+#include <linux/io.h>
+
+static void __iomem *virtio_map(unsigned long phys_addr, unsigned long pages)
+{
+ return ioremap_nocache(phys_addr, PAGE_SIZE*pages);
+}
+
+static void virtio_unmap(void __iomem *addr)
+{
+ iounmap(addr);
+}
+
+static void set_status(struct virtio_device *vdev, u8 status)
+{
+ struct platform_device *pdev = to_platform_device(vdev->dev.parent);
+ struct virtio_platform_data *pdata = pdev->dev.platform_data;
+
+ to_lgdev(vdev)->desc->status = status;
+ pdata->notify_virtio(pdev);
+}
+
+static void lg_set_status(struct virtio_device *vdev, u8 status)
+{
+ BUG_ON(!status);
+ set_status(vdev, status);
+}
+
+static void lg_reset(struct virtio_device *vdev)
+{
+ set_status(vdev, 0);
+}
+
+/*
+ * Virtqueues
+ *
+ * The other piece of infrastructure virtio needs is a "virtqueue": a way of
+ * the Guest device registering buffers for the other side to read from or
+ * write into (ie. send and receive buffers). Each device can have multiple
+ * virtqueues: for example the console driver uses one queue for sending and
+ * another for receiving.
+ *
+ * Fortunately for us, a very fast shared-memory-plus-descriptors virtqueue
+ * already exists in virtio_ring.c. We just need to connect it up.
+ *
+ * We start with the information we need to keep about each virtqueue.
+ */
+
+/*D:140 This is the information we remember about each virtqueue. */
+struct lguest_vq_info {
+ /* A copy of the information contained in the device config. */
+ struct lguest_vqconfig config;
+
+ /* The address where we mapped the virtio ring, so we can unmap it. */
+ void __iomem *pages;
+};
+
+/*
+ * When the virtio_ring code wants to prod the Host, it calls us here and we
+ * call the board specific callback. We hand a pointer to the configuration
+ * so the board code knows which virtqueue we're talking about.
+ */
+static void lg_notify(struct virtqueue *vq)
+{
+ struct platform_device *pdev = to_platform_device(vq->vdev->dev.parent);
+ struct virtio_platform_data *pdata = pdev->dev.platform_data;
+ struct lguest_vq_info *lvq = vq->priv;
+
+ pdata->notify_virtqueue(pdev, &lvq->config);
+}
+
+/*
+ * This routine finds the Nth virtqueue described in the configuration of
+ * this device and sets it up.
+ *
+ * This is kind of an ugly duckling. It'd be nicer to have a standard
+ * representation of a virtqueue in the configuration space, but it seems that
+ * everyone wants to do it differently. The KVM coders want the Guest to
+ * allocate its own pages and tell the Host where they are, but for lguest it's
+ * simpler for the Host to simply tell us where the pages are.
+ */
+static struct virtqueue *lg_find_vq(struct virtio_device *vdev,
+ unsigned index,
+ void (*callback)(struct virtqueue *vq),
+ const char *name)
+{
+ struct lguest_device *ldev = to_lgdev(vdev);
+ struct lguest_vq_info *lvq;
+ struct virtqueue *vq;
+ int err;
+
+ /* We must have this many virtqueues. */
+ if (index >= ldev->desc->num_vq)
+ return ERR_PTR(-ENOENT);
+
+ lvq = kmalloc(sizeof(*lvq), GFP_KERNEL);
+ if (!lvq)
+ return ERR_PTR(-ENOMEM);
+
+ /*
+ * Make a copy of the "struct lguest_vqconfig" entry, which sits after
+ * the descriptor. We need a copy because the config space might not
+ * be aligned correctly.
+ */
+ memcpy(&lvq->config, lg_vq(ldev->desc)+index, sizeof(lvq->config));
+
+ dev_info(&vdev->dev, "Mapping virtqueue %i addr %lx\n", index,
+ (unsigned long)lvq->config.pfn << PAGE_SHIFT);
+ /* Figure out how many pages the ring will take, and map that memory */
+ lvq->pages = virtio_map((unsigned long)lvq->config.pfn << PAGE_SHIFT,
+ DIV_ROUND_UP(vring_size(lvq->config.num,
+ LGUEST_VRING_ALIGN),
+ PAGE_SIZE));
+ if (!lvq->pages) {
+ err = -ENOMEM;
+ goto free_lvq;
+ }
+
+ /*
+ * OK, tell virtio_ring.c to set up a virtqueue now we know its size
+ * and we've got a pointer to its pages.
+ */
+ vq = vring_new_virtqueue(lvq->config.num, LGUEST_VRING_ALIGN,
+ vdev, lvq->pages, lg_notify, callback, name);
+ if (!vq) {
+ err = -ENOMEM;
+ goto unmap;
+ }
+
+ /*
+ * Tell the interrupt for this virtqueue to go to the virtio_ring
+ * interrupt handler.
+ *
+ * FIXME: We used to have a flag for the Host to tell us we could use
+ * the interrupt as a source of randomness: it'd be nice to have that
+ * back.
+ */
+ err = request_irq(lvq->config.irq, vring_interrupt, IRQF_SHARED,
+ dev_name(&vdev->dev), vq);
+ if (err)
+ goto destroy_vring;
+
+ /*
+ * Last of all we hook up our 'struct lguest_vq_info" to the
+ * virtqueue's priv pointer.
+ */
+ vq->priv = lvq;
+ return vq;
+
+destroy_vring:
+ vring_del_virtqueue(vq);
+unmap:
+ virtio_unmap(lvq->pages);
+free_lvq:
+ kfree(lvq);
+ return ERR_PTR(err);
+}
+/*:*/
+
+/* Cleaning up a virtqueue is easy */
+static void lg_del_vq(struct virtqueue *vq)
+{
+ struct lguest_vq_info *lvq = vq->priv;
+
+ /* Release the interrupt */
+ free_irq(lvq->config.irq, vq);
+ /* Tell virtio_ring.c to free the virtqueue. */
+ vring_del_virtqueue(vq);
+ /* Unmap the pages containing the ring. */
+ virtio_unmap(lvq->pages);
+ /* Free our own queue information. */
+ kfree(lvq);
+}
+
+static void lg_del_vqs(struct virtio_device *vdev)
+{
+ struct virtqueue *vq, *n;
+
+ list_for_each_entry_safe(vq, n, &vdev->vqs, list)
+ lg_del_vq(vq);
+}
+
+static int lg_find_vqs(struct virtio_device *vdev, unsigned nvqs,
+ struct virtqueue *vqs[],
+ vq_callback_t *callbacks[],
+ const char *names[])
+{
+ struct lguest_device *ldev = to_lgdev(vdev);
+ int i;
+
+ /* We must have this many virtqueues. */
+ if (nvqs > ldev->desc->num_vq)
+ return -ENOENT;
+
+ for (i = 0; i < nvqs; ++i) {
+ vqs[i] = lg_find_vq(vdev, i, callbacks[i], names[i]);
+ if (IS_ERR(vqs[i]))
+ goto error;
+ }
+ return 0;
+
+error:
+ lg_del_vqs(vdev);
+ return PTR_ERR(vqs[i]);
+}
+
+/* The ops structure which hooks everything together. */
+static struct virtio_config_ops lguest_config_ops = {
+ .get_features = lg_get_features,
+ .finalize_features = lg_finalize_features,
+ .get = lg_get,
+ .set = lg_set,
+ .get_status = lg_get_status,
+ .set_status = lg_set_status,
+ .reset = lg_reset,
+ .find_vqs = lg_find_vqs,
+ .del_vqs = lg_del_vqs,
+};
+
+static int virtio_platform_probe(struct platform_device *pdev)
+{
+ struct virtio_platform_data *pdata = pdev->dev.platform_data;
+ struct resource *res;
+ void *devices;
+
+ if (!pdata) {
+ dev_err(&pdev->dev, "no platform data defined\n");
+ return -EINVAL;
+ }
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ if (res == NULL) {
+ dev_err(&pdev->dev, "cannot find IO resource\n");
+ return -ENOENT;
+ }
+
+ /* Devices are pointed out using struct resource */
+ devices = virtio_map(res->start, resource_size(res) >> PAGE_SHIFT);
+ lg_scan_devices(devices, &pdev->dev, &lguest_config_ops);
+ return 0;
+}
+
+static int virtio_platform_remove(struct platform_device *pdev)
+{
+ return -ENOTSUPP;
+}
+
+static struct platform_driver virtio_platform_driver = {
+ .driver = {
+ .name = "virtio-platform",
+ .owner = THIS_MODULE,
+ },
+ .probe = virtio_platform_probe,
+ .remove = virtio_platform_remove,
+};
+
+static int __init virtio_platform_init(void)
+{
+ return platform_driver_register(&virtio_platform_driver);
+}
+
+static void __exit virtio_platform_exit(void)
+{
+ platform_driver_unregister(&virtio_platform_driver);
+}
+
+module_init(virtio_platform_init);
+module_exit(virtio_platform_exit);
+
+MODULE_DESCRIPTION("VirtIO Platform Driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:virtio-platform");
--- /dev/null
+++ work/include/linux/virtio_platform.h 2011-03-03 15:56:54.000000000 +0900
@@ -0,0 +1,12 @@
+#ifndef _LINUX_VIRTIO_PLATFORM_H
+#define _LINUX_VIRTIO_PLATFORM_H
+#include <linux/platform_device.h>
+#include <linux/lguest_launcher.h>
+
+struct virtio_platform_data {
+ void (*notify_virtio)(struct platform_device *pdev);
+ void (*notify_virtqueue)(struct platform_device *pdev,
+ struct lguest_vqconfig *config);
+};
+
+#endif /* _LINUX_VIRTIO_PLATFORM_H */
On Tue, Jun 21, 2011 at 06:26, Magnus Damm wrote:
> +config VIRTIO_PLATFORM
> + tristate "Platform driver for virtio devices (EXPERIMENTAL)"
> + select VIRTIO
> + select VIRTIO_RING
> + select VIRTIO_LGUEST
> + ---help---
> + This drivers provides support for virtio based paravirtual device
> + drivers over a platform bus.
> +
> + If unsure, say N.
be nice to add a note as to the name of the module if the user selects "M"
> --- /dev/null
> +++ work/drivers/virtio/virtio_platform.c 2011-03-03 16:07:31.000000000 +0900
> --- /dev/null
> +++ work/include/linux/virtio_platform.h 2011-03-03 15:56:54.000000000 +0900
both files lack a comment block at the top
/*
* one line desc of file
*
* copyright
*
* license blurb
*/
-mike
On Tue, 21 Jun 2011 19:26:05 +0900, Magnus Damm <[email protected]> wrote:
> virtio: Virtio platform driver
>
> [PATCH 01/02] virtio: Break out lguest virtio code to virtio_lguest.c
> [PATCH 02/02] virtio: Add virtio platform driver
>
> These patches add a virtio platform driver to the Linux kernel. This
> platform driver has the same role as the virtio_pci driver, but instead
> of building on top of emulated PCI this driver is making use of the
> platform bus together with driver specific callbacks.
>
> The virtio platform driver can be seen as a reusable implementation of
> the lguest virtio driver - in fact, most code is just taken directly
> from lguest_device.c and reworked to fit the platform device driver
> abstraction. The first patch breaks out code that can be shared between
> lguest and the virtio platform driver.
>
> This code has been used to implement a mailbox interface between the
> two processor cores included in the sh7372 SoC. The sh7372 contains
> one ARM Cortex-A8 and one SH4AL-DSP core, and in the prototype two
> Linux kernels are running in parallel on the same chip. Virtio serves
> as a communication link between the two cores.
OK, this seems pretty neat, but I have three questions before we nail this
down (note that lguest doesn't have an ABI, so we can change it as much
as we want).
1) The lguest bus is dumb, and I never thought about device hotplug, for
example. It would be nice to handle that somehow. Is it possible?
Is this something you care about?
2) Have you seen the '[RFC 0/8] Introducing a generic AMP/IPC framework'
patches? Seems to overlap with what you're doing after these patches.
3) The S/390 layout is identical, except their struct kvm_vqconfig is a
bit different. Perhaps we should just use theirs (they use a 64-bit
token instead of an interrupt number).
Christian?
Thanks,
Rusty.
Hi Mike,
On Wed, Jun 22, 2011 at 3:27 AM, Mike Frysinger <[email protected]> wrote:
> On Tue, Jun 21, 2011 at 06:26, Magnus Damm wrote:
>> +config VIRTIO_PLATFORM
>> + ? ? ? tristate "Platform driver for virtio devices (EXPERIMENTAL)"
>> + ? ? ? select VIRTIO
>> + ? ? ? select VIRTIO_RING
>> + ? ? ? select VIRTIO_LGUEST
>> + ? ? ? ---help---
>> + ? ? ? ?This drivers provides support for virtio based paravirtual device
>> + ? ? ? ?drivers over a platform bus.
>> +
>> + ? ? ? ?If unsure, say N.
>
> be nice to add a note as to the name of the module if the user selects "M"
Yes, good idea!
>> --- /dev/null
>> +++ work/drivers/virtio/virtio_platform.c ? ? ? 2011-03-03 16:07:31.000000000 +0900
>> --- /dev/null
>> +++ work/include/linux/virtio_platform.h ? ? ? ?2011-03-03 15:56:54.000000000 +0900
>
> both files lack a comment block at the top
> /*
> ?* one line desc of file
> ?*
> ?* copyright
> ?*
> ?* license blurb
> ?*/
Sure! I will include these changes in the next version!
Thank you!
/ magnus
What purpose this virtio platform driver serves? Are you trying to make driver layers here and each virtio device driver can hook up into this platform driver. Is that correct ?
Thanks
-Bharat
> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]] On Behalf Of
> Magnus Damm
> Sent: Tuesday, June 21, 2011 3:56 PM
> To: [email protected]
> Cc: [email protected]; [email protected]; [email protected]; Magnus
> Damm; [email protected]
> Subject: [PATCH 02/02] virtio: Add virtio platform driver
>
> From: Magnus Damm <[email protected]>
>
> This patch adds a virtio platform driver. The code is based on the lguest
> implementation available in drivers/lguest/lguest_device.c
>
> The iomem resource is used to point out the lguest device descriptor, and
> the platform data contains two separate callbacks for notification.
>
> Signed-off-by: Magnus Damm <[email protected]>
> ---
>
> drivers/virtio/Kconfig | 11 +
> drivers/virtio/Makefile | 1
> drivers/virtio/virtio_platform.c | 282
> ++++++++++++++++++++++++++++++++++++++
> include/linux/virtio_platform.h | 12 +
> 4 files changed, 306 insertions(+)
>
> --- 0002/drivers/virtio/Kconfig
> +++ work/drivers/virtio/Kconfig 2011-03-03 15:56:53.000000000 +0900
> @@ -35,3 +35,14 @@ config VIRTIO_BALLOON
>
> config VIRTIO_LGUEST
> tristate
> +
> +config VIRTIO_PLATFORM
> + tristate "Platform driver for virtio devices (EXPERIMENTAL)"
> + select VIRTIO
> + select VIRTIO_RING
> + select VIRTIO_LGUEST
> + ---help---
> + This drivers provides support for virtio based paravirtual device
> + drivers over a platform bus.
> +
> + If unsure, say N.
> --- 0002/drivers/virtio/Makefile
> +++ work/drivers/virtio/Makefile 2011-03-03 15:56:53.000000000 +0900
> @@ -3,3 +3,4 @@ obj-$(CONFIG_VIRTIO_RING) += virtio_ring
> obj-$(CONFIG_VIRTIO_PCI) += virtio_pci.o
> obj-$(CONFIG_VIRTIO_BALLOON) += virtio_balloon.o
> obj-$(CONFIG_VIRTIO_LGUEST) += virtio_lguest.o
> +obj-$(CONFIG_VIRTIO_PLATFORM) += virtio_platform.o
> --- /dev/null
> +++ work/drivers/virtio/virtio_platform.c 2011-03-03 16:07:31.000000000
> +0900
> @@ -0,0 +1,282 @@
> +#include <linux/init.h>
> +#include <linux/virtio.h>
> +#include <linux/virtio_config.h>
> +#include <linux/virtio_ring.h>
> +#include <linux/lguest_device.h>
> +#include <linux/lguest_launcher.h>
> +#include <linux/virtio_platform.h>
> +#include <linux/platform_device.h>
> +#include <linux/interrupt.h>
> +#include <linux/err.h>
> +#include <linux/slab.h>
> +#include <linux/io.h>
> +
> +static void __iomem *virtio_map(unsigned long phys_addr, unsigned long
> +pages) {
> + return ioremap_nocache(phys_addr, PAGE_SIZE*pages); }
> +
> +static void virtio_unmap(void __iomem *addr) {
> + iounmap(addr);
> +}
> +
> +static void set_status(struct virtio_device *vdev, u8 status) {
> + struct platform_device *pdev = to_platform_device(vdev-
> >dev.parent);
> + struct virtio_platform_data *pdata = pdev->dev.platform_data;
> +
> + to_lgdev(vdev)->desc->status = status;
> + pdata->notify_virtio(pdev);
> +}
> +
> +static void lg_set_status(struct virtio_device *vdev, u8 status) {
> + BUG_ON(!status);
> + set_status(vdev, status);
> +}
> +
> +static void lg_reset(struct virtio_device *vdev) {
> + set_status(vdev, 0);
> +}
> +
> +/*
> + * Virtqueues
> + *
> + * The other piece of infrastructure virtio needs is a "virtqueue": a
> +way of
> + * the Guest device registering buffers for the other side to read from
> +or
> + * write into (ie. send and receive buffers). Each device can have
> +multiple
> + * virtqueues: for example the console driver uses one queue for
> +sending and
> + * another for receiving.
> + *
> + * Fortunately for us, a very fast shared-memory-plus-descriptors
> +virtqueue
> + * already exists in virtio_ring.c. We just need to connect it up.
> + *
> + * We start with the information we need to keep about each virtqueue.
> + */
> +
> +/*D:140 This is the information we remember about each virtqueue. */
> +struct lguest_vq_info {
> + /* A copy of the information contained in the device config. */
> + struct lguest_vqconfig config;
> +
> + /* The address where we mapped the virtio ring, so we can unmap it.
> */
> + void __iomem *pages;
> +};
> +
> +/*
> + * When the virtio_ring code wants to prod the Host, it calls us here
> +and we
> + * call the board specific callback. We hand a pointer to the
> +configuration
> + * so the board code knows which virtqueue we're talking about.
> + */
> +static void lg_notify(struct virtqueue *vq) {
> + struct platform_device *pdev = to_platform_device(vq->vdev-
> >dev.parent);
> + struct virtio_platform_data *pdata = pdev->dev.platform_data;
> + struct lguest_vq_info *lvq = vq->priv;
> +
> + pdata->notify_virtqueue(pdev, &lvq->config); }
> +
> +/*
> + * This routine finds the Nth virtqueue described in the configuration
> +of
> + * this device and sets it up.
> + *
> + * This is kind of an ugly duckling. It'd be nicer to have a standard
> + * representation of a virtqueue in the configuration space, but it
> +seems that
> + * everyone wants to do it differently. The KVM coders want the Guest
> +to
> + * allocate its own pages and tell the Host where they are, but for
> +lguest it's
> + * simpler for the Host to simply tell us where the pages are.
> + */
> +static struct virtqueue *lg_find_vq(struct virtio_device *vdev,
> + unsigned index,
> + void (*callback)(struct virtqueue *vq),
> + const char *name)
> +{
> + struct lguest_device *ldev = to_lgdev(vdev);
> + struct lguest_vq_info *lvq;
> + struct virtqueue *vq;
> + int err;
> +
> + /* We must have this many virtqueues. */
> + if (index >= ldev->desc->num_vq)
> + return ERR_PTR(-ENOENT);
> +
> + lvq = kmalloc(sizeof(*lvq), GFP_KERNEL);
> + if (!lvq)
> + return ERR_PTR(-ENOMEM);
> +
> + /*
> + * Make a copy of the "struct lguest_vqconfig" entry, which sits
> after
> + * the descriptor. We need a copy because the config space might
> not
> + * be aligned correctly.
> + */
> + memcpy(&lvq->config, lg_vq(ldev->desc)+index, sizeof(lvq->config));
> +
> + dev_info(&vdev->dev, "Mapping virtqueue %i addr %lx\n", index,
> + (unsigned long)lvq->config.pfn << PAGE_SHIFT);
> + /* Figure out how many pages the ring will take, and map that
> memory */
> + lvq->pages = virtio_map((unsigned long)lvq->config.pfn <<
> PAGE_SHIFT,
> + DIV_ROUND_UP(vring_size(lvq->config.num,
> + LGUEST_VRING_ALIGN),
> + PAGE_SIZE));
> + if (!lvq->pages) {
> + err = -ENOMEM;
> + goto free_lvq;
> + }
> +
> + /*
> + * OK, tell virtio_ring.c to set up a virtqueue now we know its
> size
> + * and we've got a pointer to its pages.
> + */
> + vq = vring_new_virtqueue(lvq->config.num, LGUEST_VRING_ALIGN,
> + vdev, lvq->pages, lg_notify, callback, name);
> + if (!vq) {
> + err = -ENOMEM;
> + goto unmap;
> + }
> +
> + /*
> + * Tell the interrupt for this virtqueue to go to the virtio_ring
> + * interrupt handler.
> + *
> + * FIXME: We used to have a flag for the Host to tell us we could
> use
> + * the interrupt as a source of randomness: it'd be nice to have
> that
> + * back.
> + */
> + err = request_irq(lvq->config.irq, vring_interrupt, IRQF_SHARED,
> + dev_name(&vdev->dev), vq);
> + if (err)
> + goto destroy_vring;
> +
> + /*
> + * Last of all we hook up our 'struct lguest_vq_info" to the
> + * virtqueue's priv pointer.
> + */
> + vq->priv = lvq;
> + return vq;
> +
> +destroy_vring:
> + vring_del_virtqueue(vq);
> +unmap:
> + virtio_unmap(lvq->pages);
> +free_lvq:
> + kfree(lvq);
> + return ERR_PTR(err);
> +}
> +/*:*/
> +
> +/* Cleaning up a virtqueue is easy */
> +static void lg_del_vq(struct virtqueue *vq) {
> + struct lguest_vq_info *lvq = vq->priv;
> +
> + /* Release the interrupt */
> + free_irq(lvq->config.irq, vq);
> + /* Tell virtio_ring.c to free the virtqueue. */
> + vring_del_virtqueue(vq);
> + /* Unmap the pages containing the ring. */
> + virtio_unmap(lvq->pages);
> + /* Free our own queue information. */
> + kfree(lvq);
> +}
> +
> +static void lg_del_vqs(struct virtio_device *vdev) {
> + struct virtqueue *vq, *n;
> +
> + list_for_each_entry_safe(vq, n, &vdev->vqs, list)
> + lg_del_vq(vq);
> +}
> +
> +static int lg_find_vqs(struct virtio_device *vdev, unsigned nvqs,
> + struct virtqueue *vqs[],
> + vq_callback_t *callbacks[],
> + const char *names[])
> +{
> + struct lguest_device *ldev = to_lgdev(vdev);
> + int i;
> +
> + /* We must have this many virtqueues. */
> + if (nvqs > ldev->desc->num_vq)
> + return -ENOENT;
> +
> + for (i = 0; i < nvqs; ++i) {
> + vqs[i] = lg_find_vq(vdev, i, callbacks[i], names[i]);
> + if (IS_ERR(vqs[i]))
> + goto error;
> + }
> + return 0;
> +
> +error:
> + lg_del_vqs(vdev);
> + return PTR_ERR(vqs[i]);
> +}
> +
> +/* The ops structure which hooks everything together. */ static struct
> +virtio_config_ops lguest_config_ops = {
> + .get_features = lg_get_features,
> + .finalize_features = lg_finalize_features,
> + .get = lg_get,
> + .set = lg_set,
> + .get_status = lg_get_status,
> + .set_status = lg_set_status,
> + .reset = lg_reset,
> + .find_vqs = lg_find_vqs,
> + .del_vqs = lg_del_vqs,
> +};
> +
> +static int virtio_platform_probe(struct platform_device *pdev) {
> + struct virtio_platform_data *pdata = pdev->dev.platform_data;
> + struct resource *res;
> + void *devices;
> +
> + if (!pdata) {
> + dev_err(&pdev->dev, "no platform data defined\n");
> + return -EINVAL;
> + }
> +
> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + if (res == NULL) {
> + dev_err(&pdev->dev, "cannot find IO resource\n");
> + return -ENOENT;
> + }
> +
> + /* Devices are pointed out using struct resource */
> + devices = virtio_map(res->start, resource_size(res) >> PAGE_SHIFT);
> + lg_scan_devices(devices, &pdev->dev, &lguest_config_ops);
> + return 0;
> +}
> +
> +static int virtio_platform_remove(struct platform_device *pdev) {
> + return -ENOTSUPP;
> +}
> +
> +static struct platform_driver virtio_platform_driver = {
> + .driver = {
> + .name = "virtio-platform",
> + .owner = THIS_MODULE,
> + },
> + .probe = virtio_platform_probe,
> + .remove = virtio_platform_remove,
> +};
> +
> +static int __init virtio_platform_init(void) {
> + return platform_driver_register(&virtio_platform_driver);
> +}
> +
> +static void __exit virtio_platform_exit(void) {
> + platform_driver_unregister(&virtio_platform_driver);
> +}
> +
> +module_init(virtio_platform_init);
> +module_exit(virtio_platform_exit);
> +
> +MODULE_DESCRIPTION("VirtIO Platform Driver"); MODULE_LICENSE("GPL");
> +MODULE_ALIAS("platform:virtio-platform");
> --- /dev/null
> +++ work/include/linux/virtio_platform.h 2011-03-03 15:56:54.000000000
> +0900
> @@ -0,0 +1,12 @@
> +#ifndef _LINUX_VIRTIO_PLATFORM_H
> +#define _LINUX_VIRTIO_PLATFORM_H
> +#include <linux/platform_device.h>
> +#include <linux/lguest_launcher.h>
> +
> +struct virtio_platform_data {
> + void (*notify_virtio)(struct platform_device *pdev);
> + void (*notify_virtqueue)(struct platform_device *pdev,
> + struct lguest_vqconfig *config);
> +};
> +
> +#endif /* _LINUX_VIRTIO_PLATFORM_H */
> _______________________________________________
> Virtualization mailing list
> [email protected]
> https://lists.linux-foundation.org/mailman/listinfo/virtualization
Hi Bhushan Bharat,
On Thu, Jun 23, 2011 at 5:54 PM, Bhushan Bharat-R65777
<[email protected]> wrote:
> What purpose this virtio platform driver serves? Are you trying to make driver layers here and each virtio device driver can hook up into this platform driver. Is that correct ?
The idea behind the virto platform driver is to have a reusable layer
that handles common virtio and vring functionality. Regular virtio
drivers for console, network and disk and interfacing to the virtio
platform driver, so these paravirtualized drivers can with this virtio
platform driver easily be reused by embedded platforms.
Vendor specific code is abstracted away from the virtio platform
driver and interfaced to using regular interrupts and SoC-specific
callbacks. So with this patch virtio can be interfaced as any regular
platform driver. This version of the driver is simply reusing the
configuration method from lguest.
If you want to see all code involved (including extremely experimental
backing drivers) then have a look at:
http://www.spinics.net/lists/linux-sh/msg07188.html
Cheers,
/ magnus
Thanks for the explanation. I also thought of same purpose for this patch but I got confused by function names and data structure names in the patch. They still have lguest in it.
Thanks
-Bharat
> -----Original Message-----
> From: Magnus Damm [mailto:[email protected]]
> Sent: Friday, June 24, 2011 6:44 AM
> To: Bhushan Bharat-R65777
> Cc: [email protected]; [email protected]; [email protected];
> [email protected]; [email protected]
> Subject: Re: [PATCH 02/02] virtio: Add virtio platform driver
>
> Hi Bhushan Bharat,
>
> On Thu, Jun 23, 2011 at 5:54 PM, Bhushan Bharat-R65777
> <[email protected]> wrote:
> > What purpose this virtio platform driver serves? Are you trying to make
> driver layers here and each virtio device driver can hook up into this
> platform driver. Is that correct ?
>
> The idea behind the virto platform driver is to have a reusable layer
> that handles common virtio and vring functionality. Regular virtio
> drivers for console, network and disk and interfacing to the virtio
> platform driver, so these paravirtualized drivers can with this virtio
> platform driver easily be reused by embedded platforms.
>
> Vendor specific code is abstracted away from the virtio platform driver
> and interfaced to using regular interrupts and SoC-specific callbacks. So
> with this patch virtio can be interfaced as any regular platform driver.
> This version of the driver is simply reusing the configuration method
> from lguest.
>
> If you want to see all code involved (including extremely experimental
> backing drivers) then have a look at:
> http://www.spinics.net/lists/linux-sh/msg07188.html
>
> Cheers,
>
> / magnus
On Wed, Jun 22, 2011 at 11:09 AM, Rusty Russell <[email protected]> wrote:
> On Tue, 21 Jun 2011 19:26:05 +0900, Magnus Damm <[email protected]> wrote:
>> virtio: Virtio platform driver
>>
>> [PATCH 01/02] virtio: Break out lguest virtio code to virtio_lguest.c
>> [PATCH 02/02] virtio: Add virtio platform driver
>>
>> These patches add a virtio platform driver to the Linux kernel. This
>> platform driver has the same role as the virtio_pci driver, but instead
>> of building on top of emulated PCI this driver is making use of the
>> platform bus together with driver specific callbacks.
>>
>> The virtio platform driver can be seen as a reusable implementation of
>> the lguest virtio driver - in fact, most code is just taken directly
>> from lguest_device.c and reworked to fit the platform device driver
>> abstraction. The first patch breaks out code that can be shared between
>> lguest and the virtio platform driver.
>>
>> This code has been used to implement a mailbox interface between the
>> two processor cores included in the sh7372 SoC. The sh7372 contains
>> one ARM Cortex-A8 and one SH4AL-DSP core, and in the prototype two
>> Linux kernels are running in parallel on the same chip. Virtio serves
>> as a communication link between the two cores.
Hi Rusty,
Thanks for your comments!
> OK, this seems pretty neat, but I have three questions before we nail this
> down (note that lguest doesn't have an ABI, so we can change it as much
> as we want).
>
> 1) The lguest bus is dumb, and I never thought about device hotplug, for
> ? example. ?It would be nice to handle that somehow. ?Is it possible?
> ? Is this something you care about?
I would most likely use device hotplug if it already existed, but my
goal with this patch and the rest of the sh7372 AMP code is to show
that virtio exists and that there is no need for people to invent
their own IPC software mechanism. So I don't care that much about
device hotplug.
I do however care about ABI and a non-GPL licensed virtio library to
allow people to tie in commercial RTOS with virtio. To prevent them
from rolling their own. It's pretty low priority though, I am quite
happy as-is staying in proof-of-concept-land running two instances of
Linux.
> 2) Have you seen the '[RFC 0/8] Introducing a generic AMP/IPC framework'
> ? patches? ?Seems to overlap with what you're doing after these patches.
Yes, there is clearly overlap, but surprisingly little. I believe
we're trying to solve different sides of the same problem.
Lguest system (Linux + Linux):
Host: lguest.c (user space) talks to /dev/lguest
Guest: lguest_device.c ties in virtio devices
SH Core Linux system (Linux + Linux):
Host: SoC-specific rtcpu-loader.c (user space) talks to /dev/uioX
Slave: SoC-specific code chats to virtio_platform.c that ties in virtio devices
"generic AMP/IPC framework" (Linux + DSP/RTOS):
Host: "remoteproc" and "rpmsg" run in the kernel
Slave: ?? (not covered by the patches I believe)
So while the "generic AMP/IPC framework" looks great for the host,
this patch tries to make something reusable on the slave/guest side.
> 3) The S/390 layout is identical, except their struct kvm_vqconfig is a
> ? bit different. ?Perhaps we should just use theirs (they use a 64-bit
> ? token instead of an interrupt number).
I don't mind so much, but alignment wise I find it odd that the s390
version chose to use u64 + u64 + u16.
Thanks,
/ magnus