Re: [PATCH v2 05/15] s390: vfio-ap: base implementation of VFIO AP device driver

From: Tony Krowiak
Date: Wed Feb 28 2018 - 11:43:58 EST

On 02/28/2018 10:33 AM, Pierre Morel wrote:
On 27/02/2018 15:28, Tony Krowiak wrote:
Introduces a new AP device driver. This device driver
is built on the VFIO mediated device framework. The framework
provides sysfs interfaces that facilitate passthrough
access by guests to devices installed on the linux host.

The VFIO AP device driver will serve two purposes:

1. Provide the interfaces to reserve AP devices for exclusive
use by KVM guests. This is accomplished by unbinding the
devices to be reserved for guest usage from the default AP
device driver and binding them to the VFIO AP device driver.

2. Implements the functions, callbacks and sysfs attribute
interfaces required to create one or more VFIO mediated
devices each of which will be used to configure the AP
matrix for a guest and serve as a file descriptor
for facilitating communication between QEMU and the
VFIO AP device driver.

When the VFIO AP device driver is initialized:

* It registers with the AP bus for control of type 10 (CEX4
and newer) AP queue devices. The probe and remove callbacks
will be provided to support the binding/unbinding of
AP queue devices to/from the VFIO AP device driver.

* Creates a /sys/devices/vfio-ap/matrix device to hold
the APQNs of the AP devices bound to the VFIO
AP device driver and serves as the parent of the
mediated devices created for each guest.

Signed-off-by: Tony Krowiak <akrowiak@xxxxxxxxxxxxxxxxxx>
---
MAINTAINERS | 2 +
arch/s390/Kconfig | 8 ++
arch/s390/configs/default_defconfig | 3 +
arch/s390/configs/gcov_defconfig | 3 +
arch/s390/configs/performance_defconfig | 3 +
arch/s390/defconfig | 3 +
drivers/s390/crypto/Makefile | 4 +
drivers/s390/crypto/vfio_ap_drv.c | 134 +++++++++++++++++++++++++++++++
drivers/s390/crypto/vfio_ap_private.h | 20 +++++
include/uapi/linux/vfio.h | 2 +
10 files changed, 182 insertions(+), 0 deletions(-)
create mode 100644 drivers/s390/crypto/vfio_ap_drv.c
create mode 100644 drivers/s390/crypto/vfio_ap_private.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 4acf7c2..a2f232d 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -11884,6 +11884,8 @@ W: http://www.ibm.com/developerworks/linux/linux390/
S: Supported
F: arch/s390/include/asm/kvm/kvm-ap.h
F: arch/s390/kvm/kvm-ap.c
+F: drivers/s390/crypto/vfio_ap_drv.c
+F: drivers/s390/crypto/vfio_ap_private.h

S390 ZFCP DRIVER
M: Steffen Maier <maier@xxxxxxxxxxxxxxxxxx>
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index cbe1d97..9f23caf 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -771,6 +771,14 @@ config VFIO_CCW
To compile this driver as a module, choose M here: the
module will be called vfio_ccw.

+config VFIO_AP
+ def_tristate m
+ prompt "Support for virtual Adjunct Processor device interface"

The VFIO AP devices are not virtual.
What about
"VFIO support for AP devices"
Sounds good.

+ depends on ZCRYPT && VFIO_MDEV_DEVICE
+ help
+ driver grants access to Adjunct Processor (AP) devices
+ via the VFIO mediated device interface.
+
endmenu

menu "Dump support"
diff --git a/arch/s390/configs/default_defconfig b/arch/s390/configs/default_defconfig
index 5af8458..40fa3f6 100644
--- a/arch/s390/configs/default_defconfig
+++ b/arch/s390/configs/default_defconfig

Not sure that this file belongs to this patch
Neither am I, but at the time I inserted this here - well before August of last year - I was using vfio-ccw as a model.
If someone can verify this does not belong here, I'd be more than happy to remove it.


@@ -719,3 +719,6 @@ CONFIG_APPLDATA_BASE=y
CONFIG_KVM=m
CONFIG_KVM_S390_UCONTROL=y
CONFIG_VHOST_NET=m
+VFIO_MDEV=m
+VFIO_MDEV_DEVICE=m
+CONFIG_VFIO_AP=m

What is your goal when modifying this three files?
Could you add a comment in the commit message?
As stated above, this was originally based on the vfio-ccw model and has been in the
patch series since its inception. I'd be happy to remove it if it is not necessary.



diff --git a/arch/s390/configs/gcov_defconfig b/arch/s390/configs/gcov_defconfig
index d52eafe..377d40f 100644
--- a/arch/s390/configs/gcov_defconfig
+++ b/arch/s390/configs/gcov_defconfig
@@ -659,3 +659,6 @@ CONFIG_APPLDATA_BASE=y
CONFIG_KVM=m
CONFIG_KVM_S390_UCONTROL=y
CONFIG_VHOST_NET=m
+VFIO_MDEV=m
+VFIO_MDEV_DEVICE=m
+CONFIG_VFIO_AP=m
diff --git a/arch/s390/configs/performance_defconfig b/arch/s390/configs/performance_defconfig
index 20ed149..f0c52df 100644
--- a/arch/s390/configs/performance_defconfig
+++ b/arch/s390/configs/performance_defconfig
@@ -657,3 +657,6 @@ CONFIG_APPLDATA_BASE=y
CONFIG_KVM=m
CONFIG_KVM_S390_UCONTROL=y
CONFIG_VHOST_NET=m
+VFIO_MDEV=m
+VFIO_MDEV_DEVICE=m
+CONFIG_VFIO_AP=m
diff --git a/arch/s390/defconfig b/arch/s390/defconfig
index 46a3178..0996eb7 100644
--- a/arch/s390/defconfig
+++ b/arch/s390/defconfig
@@ -239,3 +239,6 @@ CONFIG_CRC7=m
# CONFIG_XZ_DEC_ARMTHUMB is not set
# CONFIG_XZ_DEC_SPARC is not set
CONFIG_CMM=m
+VFIO_MDEV=m
+VFIO_MDEV_DEVICE=m
+CONFIG_VFIO_AP=m
diff --git a/drivers/s390/crypto/Makefile b/drivers/s390/crypto/Makefile
index b59af54..48e466e 100644
--- a/drivers/s390/crypto/Makefile
+++ b/drivers/s390/crypto/Makefile
@@ -15,3 +15,7 @@ obj-$(CONFIG_ZCRYPT) += zcrypt_pcixcc.o zcrypt_cex2a.o zcrypt_cex4.o
# pkey kernel module
pkey-objs := pkey_api.o
obj-$(CONFIG_PKEY) += pkey.o
+
+# adjunct processor matrix
+vfio_ap-objs := vfio_ap_drv.o
+obj-$(CONFIG_VFIO_AP) += vfio_ap.o
diff --git a/drivers/s390/crypto/vfio_ap_drv.c b/drivers/s390/crypto/vfio_ap_drv.c
new file mode 100644
index 0000000..8bb72af
--- /dev/null
+++ b/drivers/s390/crypto/vfio_ap_drv.c
@@ -0,0 +1,134 @@
+/*
+ * VFIO based AP device driver
+ *
+ * Copyright IBM Corp. 2017
+ *
+ * Author(s): Tony Krowiak <akrowiak@xxxxxxxxxxxxxxxxxx>
+ */
+
+#include <linux/module.h>
+#include <linux/mod_devicetable.h>
+#include <linux/slab.h>
+
+#include "ap_bus.h"

Since you do it in a later patch, may be put this include of ap_bus.h in ap_private.h now.
Okay


+#include "vfio_ap_private.h"
+
+#define VFIO_AP_ROOT_NAME "vfio_ap"
+#define VFIO_AP_DEV_TYPE_NAME "ap_matrix"
+#define VFIO_AP_DEV_NAME "matrix"
+
+MODULE_AUTHOR("IBM Corporation");
+MODULE_DESCRIPTION("VFIO AP device driver, Copyright IBM Corp. 2017");
+MODULE_LICENSE("GPL v2");
+
+static struct device *vfio_ap_root_device;
+
+static struct ap_driver vfio_ap_drv;
+
+static struct ap_matrix *ap_matrix;
+
+static struct device_type vfio_ap_dev_type = {
+ .name = VFIO_AP_DEV_TYPE_NAME,
+};
+
+/* Only type 10 adapters (CEX4 and later) are supported
+ * by the AP matrix device driver
+ */
+static struct ap_device_id ap_queue_ids[] = {
+ { .dev_type = AP_DEVICE_TYPE_CEX4,
+ .match_flags = AP_DEVICE_ID_MATCH_QUEUE_TYPE },
+ { .dev_type = AP_DEVICE_TYPE_CEX5,
+ .match_flags = AP_DEVICE_ID_MATCH_QUEUE_TYPE },
+ { .dev_type = AP_DEVICE_TYPE_CEX6,
+ .match_flags = AP_DEVICE_ID_MATCH_QUEUE_TYPE },
+ { /* end of sibling */ },
+};
+
+MODULE_DEVICE_TABLE(vfio_ap, ap_queue_ids);
+
+static int vfio_ap_queue_dev_probe(struct ap_device *apdev)
+{
+ return 0;
+}
+
+static void vfio_ap_matrix_dev_release(struct device *dev)
+{
+ struct ap_matrix *ap_matrix = dev_get_drvdata(dev);
+
+ kfree(ap_matrix);
+}
+
+static int vfio_ap_matrix_dev_create(void)
+{
+ int ret;
+
+ vfio_ap_root_device = root_device_register(VFIO_AP_ROOT_NAME);
+
+ ret = PTR_ERR_OR_ZERO(vfio_ap_root_device);

IS_ERR() is enough, root_device_register() never return NULL.
I searched the kernel code to look at other places the root_device_register()
function is called to see how the return value is handled. I've seen all of the
following used:
if (IS_ERR())
ret = PTR_ERR()
PTR_ERR()
PTR_ERR_OR_ZERO()

I'm not sure why this is a concern, but I'll use the first option above
since PTR_ERR_OR_ZERO() also embeds the first option.
+ if (ret)
+ goto done;
+
+ ap_matrix = kzalloc(sizeof(*ap_matrix), GFP_KERNEL);
+ if (!ap_matrix) {
+ ret = -ENOMEM;
+ goto matrix_alloc_err;
+ }
+
+ ap_matrix->device.type = &vfio_ap_dev_type;
+ dev_set_name(&ap_matrix->device, "%s", VFIO_AP_DEV_NAME);
+ ap_matrix->device.parent = vfio_ap_root_device;
+ ap_matrix->device.release = vfio_ap_matrix_dev_release;
+ ap_matrix->device.driver = &vfio_ap_drv.driver;
+
+ ret = device_register(&ap_matrix->device);
+ if (ret)
+ goto matrix_reg_err;
+
+ goto done;
+
+matrix_reg_err:
+ put_device(&ap_matrix->device);
+ kfree(ap_matrix);
+
+matrix_alloc_err:
+ root_device_unregister(vfio_ap_root_device);
+
+done:
+ return ret;
+}
+
+static void vfio_ap_matrix_dev_destroy(struct ap_matrix *ap_matrix)
+{
+ device_unregister(&ap_matrix->device);
+ root_device_unregister(vfio_ap_root_device);
+}
+
+int __init vfio_ap_init(void)
+{
+ int ret;
+
+ ret = vfio_ap_matrix_dev_create();
+ if (ret)
+ return ret;
+
+ memset(&vfio_ap_drv, 0, sizeof(vfio_ap_drv));
+ vfio_ap_drv.probe = vfio_ap_queue_dev_probe;
+ vfio_ap_drv.ids = ap_queue_ids;
+
+ ret = ap_driver_register(&vfio_ap_drv, THIS_MODULE, VFIO_AP_DRV_NAME);
+ if (ret) {
+ vfio_ap_matrix_dev_destroy(ap_matrix);
+ return ret;
+ }
+
+ return 0;
+}
+
+void __exit vfio_ap_exit(void)
+{
+ ap_driver_unregister(&vfio_ap_drv);
+ vfio_ap_matrix_dev_destroy(ap_matrix);
+}
+
+module_init(vfio_ap_init);
+module_exit(vfio_ap_exit);
diff --git a/drivers/s390/crypto/vfio_ap_private.h b/drivers/s390/crypto/vfio_ap_private.h
new file mode 100644
index 0000000..3505947
--- /dev/null
+++ b/drivers/s390/crypto/vfio_ap_private.h
@@ -0,0 +1,20 @@
+/*
+ * Private data and functions for adjunct processor VFIO matrix driver.
+ *
+ * Copyright IBM Corp. 2017
+ * Author(s): Tony Krowiak <akrowiak@xxxxxxxxxxxxxxxxxx>
+ */
+
+#ifndef _VFIO_AP_PRIVATE_H_
+#define _VFIO_AP_PRIVATE_H_
+
+#include <linux/types.h>
+
+#define VFIO_AP_MODULE_NAME "vfio_ap"
+#define VFIO_AP_DRV_NAME "vfio_ap"
+
+struct ap_matrix {
+ struct device device;
+};
+
+#endif /* _VFIO_AP_PRIVATE_H_ */
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index e3301db..cf2a5e9 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -200,6 +200,7 @@ struct vfio_device_info {
#define VFIO_DEVICE_FLAGS_PLATFORM (1 << 2) /* vfio-platform device */
#define VFIO_DEVICE_FLAGS_AMBA (1 << 3) /* vfio-amba device */
#define VFIO_DEVICE_FLAGS_CCW (1 << 4) /* vfio-ccw device */
+#define VFIO_DEVICE_FLAGS_AP (1 << 5) /* vfio-ap device */
__u32 num_regions; /* Max region index + 1 */
__u32 num_irqs; /* Max IRQ index + 1 */
};
@@ -215,6 +216,7 @@ struct vfio_device_info {
#define VFIO_DEVICE_API_PLATFORM_STRING "vfio-platform"
#define VFIO_DEVICE_API_AMBA_STRING "vfio-amba"
#define VFIO_DEVICE_API_CCW_STRING "vfio-ccw"
+#define VFIO_DEVICE_API_AP_STRING "vfio-ap"

/**
* VFIO_DEVICE_GET_REGION_INFO - _IOWR(VFIO_TYPE, VFIO_BASE + 8,