virtio: Virtio platform driver

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.

Tested on the SH architecture, but should work on any architecture.

---

 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.

---

 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(-)

@@ -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

@@ -33,3 +33,5 @@ config VIRTIO_BALLOON
 
 	 If unsure, say M.
 
+config VIRTIO_LGUEST
+	tristate

@@ -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

@@ -71,5 +71,6 @@ struct lguest_data {
 	unsigned int syscall_vec;
 };
 extern struct lguest_data lguest_data;
+
 #endif /* __ASSEMBLY__ */
 #endif	/* _LINUX_LGUEST_H */

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.

---

 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(-)

@@ -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

@@ -33,3 +33,5 @@ config VIRTIO_BALLOON
 
 	 If unsure, say M.
 
+config VIRTIO_LGUEST
+	tristate

@@ -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

@@ -71,5 +71,6 @@ struct lguest_data {
 	unsigned int syscall_vec;
 };
 extern struct lguest_data lguest_data;
+
 #endif /* __ASSEMBLY__ */
 #endif	/* _LINUX_LGUEST_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.

---

 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(+)

@@ -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.

@@ -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

@@ -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 */

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.

---

 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(+)

@@ -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.

@@ -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

@@ -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 */

I have no problem with these patches, but it's just churn until we see your actual drivers.

The S/390 devs might be interested, as their bus is very similar too...

Cheers,
Rusty.

I have no problem with these patches, but it's just churn until we see your actual drivers.

The S/390 devs might be interested, as their bus is very similar too...

Cheers,
Rusty.

Hi Rusty,

Well, actually this platform driver is used together with already existing drivers, so there are no new virtio drivers to wait for.

The drivers that have been tested are so far:

CONFIG_VIRTIO_CONSOLE=y
CONFIG_VIRTIO_NET=y

At this point there are four different pieces of code working together

1) Virtio platform driver patches (for guest)
2) SH4AL-DSP guest kernel patch
3) ARM UIO driver patches (for host)
4) User space backing code for ARM based on lguest.c

These patches in this mail thread are 1), and I decided to brush up that portion and submit upstream because it's the part that is easiest to break out. I intend to post the rest bit by bit over time, but if someone is interested then I can post everything at once too.

The lguest device code is very similar as well, perhaps it's worth refactoring that a bit to build on top of the platform driver. Not sure if you see that as a move in the right direction though.

Thanks for your feedback!

/ magnus

I'm very interested in the full series of patches. I want to do something similar to talk between two Linux kernels (x86 and PowerPC) connected by a PCI bus.

Thanks,
Ira

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.

Cheers,

/ magnus

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.

Cheers,

/ magnus

I'm very interested in the full series of patches. I want to do something similar to talk between two Linux kernels (x86 and PowerPC) connected by a PCI bus.

Thanks,
Ira

Hi Rusty,

Well, actually this platform driver is used together with already existing drivers, so there are no new virtio drivers to wait for.

The drivers that have been tested are so far:

CONFIG_VIRTIO_CONSOLE=y
CONFIG_VIRTIO_NET=y

At this point there are four different pieces of code working together

1) Virtio platform driver patches (for guest)
2) SH4AL-DSP guest kernel patch
3) ARM UIO driver patches (for host)
4) User space backing code for ARM based on lguest.c

These patches in this mail thread are 1), and I decided to brush up that portion and submit upstream because it's the part that is easiest to break out. I intend to post the rest bit by bit over time, but if someone is interested then I can post everything at once too.

The lguest device code is very similar as well, perhaps it's worth refactoring that a bit to build on top of the platform driver. Not sure if you see that as a move in the right direction though.

Thanks for your feedback!

/ magnus