[PATCH v4 0/6] kvm: Make ioeventfd usable on s390.

[PATCH v4 0/6] kvm: Make ioeventfd usable on s390.

[Cornelia Huck]

Here's v4 of the ioeventfd for s390 patch set.

The most interesting change is the addition of MST's cookie patch,
which enhances the virtio-ccw notify hypercall for future performance
optimizations. This patch should go in for 3.9.

I'd love to see the other patches in 3.9 as well; but I wouldn't
mind postponing them to 3.10, your call.

v3 -> v4:
- Pass cookies in virtio-ccw notify hypercall
- Coding style
v2 -> v3:
- Added a patch exporting the virtio-ccw api and use it for the
  diagnose implementation.
- Better naming: We're dealing with virtio-ccw notifications only.
v1 -> v2:
- Move irqfd initialization from a module init function to kvm_init,
  eliminating the need for a second module for kvm/s390.
- Use kvm_io_device for s390 css devices.

Cornelia Huck (5):
  KVM: s390: Export virtio-ccw api.
  KVM: Initialize irqfd from kvm_init().
  KVM: Introduce KVM_VIRTIO_CCW_NOTIFY_BUS.
  KVM: ioeventfd for virtio-ccw devices.
  KVM: s390: Wire up ioeventfd.

Michael S. Tsirkin (1):
  virtio_ccw: pass a cookie value to kvm hypercall

 Documentation/virtual/kvm/api.txt       |  8 ++++++++
 arch/s390/include/uapi/asm/Kbuild       |  1 +
 arch/s390/include/uapi/asm/virtio-ccw.h | 21 +++++++++++++++++++++
 arch/s390/kvm/Kconfig                   |  1 +
 arch/s390/kvm/Makefile                  |  2 +-
 arch/s390/kvm/diag.c                    | 26 ++++++++++++++++++++++++++
 arch/s390/kvm/kvm-s390.c                |  1 +
 drivers/s390/kvm/virtio_ccw.c           | 16 +++++++++-------
 include/linux/kvm_host.h                | 14 ++++++++++++++
 include/uapi/linux/kvm.h                |  3 +++
 virt/kvm/eventfd.c                      | 24 +++++++++++++++---------
 virt/kvm/kvm_main.c                     |  6 ++++++
 12 files changed, 106 insertions(+), 17 deletions(-)
 create mode 100644 arch/s390/include/uapi/asm/virtio-ccw.h

-- 
1.7.12.4

[PATCH v4 1/6] virtio_ccw: pass a cookie value to kvm hypercall

[Cornelia Huck]

From: "Michael S. Tsirkin" <mst@redhat.com>

Lookups by channel/vq pair on host during virtio notifications might be
expensive.  Interpret hypercall return value as a cookie which host can
use to do device lookups for the next notification more efficiently.

[CH: Fix line > 80 chars]
Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
---
 drivers/s390/kvm/virtio_ccw.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/s390/kvm/virtio_ccw.c b/drivers/s390/kvm/virtio_ccw.c
index 3217dfe..259a2fb 100644
--- a/drivers/s390/kvm/virtio_ccw.c
+++ b/drivers/s390/kvm/virtio_ccw.c
@@ -77,6 +77,7 @@ struct virtio_ccw_vq_info {
 	void *queue;
 	struct vq_info_block *info_block;
 	struct list_head node;
+	long cookie;
 };
 
 #define KVM_VIRTIO_CCW_RING_ALIGN 4096
@@ -145,15 +146,18 @@ static int ccw_io_helper(struct virtio_ccw_device *vcdev,
 }
 
 static inline long do_kvm_notify(struct subchannel_id schid,
-				 unsigned long queue_index)
+				 unsigned long queue_index,
+				 long cookie)
 {
 	register unsigned long __nr asm("1") = KVM_S390_VIRTIO_CCW_NOTIFY;
 	register struct subchannel_id __schid asm("2") = schid;
 	register unsigned long __index asm("3") = queue_index;
 	register long __rc asm("2");
+	register long __cookie asm("4") = cookie;
 
 	asm volatile ("diag 2,4,0x500\n"
-		      : "=d" (__rc) : "d" (__nr), "d" (__schid), "d" (__index)
+		      : "=d" (__rc) : "d" (__nr), "d" (__schid), "d" (__index),
+		      "d"(__cookie)
 		      : "memory", "cc");
 	return __rc;
 }
@@ -166,7 +170,8 @@ static void virtio_ccw_kvm_notify(struct virtqueue *vq)
 
 	vcdev = to_vc_device(info->vq->vdev);
 	ccw_device_get_schid(vcdev->cdev, &schid);
-	do_kvm_notify(schid, virtqueue_get_queue_index(vq));
+	info->cookie = do_kvm_notify(schid, virtqueue_get_queue_index(vq),
+				     info->cookie);
 }
 
 static int virtio_ccw_read_vq_conf(struct virtio_ccw_device *vcdev,
-- 
1.7.12.4

[PATCH v4 2/6] KVM: s390: Export virtio-ccw api.

[Cornelia Huck]

Export the virtio-ccw api in a header for usage by other code.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
---
 arch/s390/include/uapi/asm/Kbuild       |  1 +
 arch/s390/include/uapi/asm/virtio-ccw.h | 21 +++++++++++++++++++++
 drivers/s390/kvm/virtio_ccw.c           |  5 +----
 3 files changed, 23 insertions(+), 4 deletions(-)
 create mode 100644 arch/s390/include/uapi/asm/virtio-ccw.h

diff --git a/arch/s390/include/uapi/asm/Kbuild b/arch/s390/include/uapi/asm/Kbuild
index 7bf68ff..9ccd190 100644
--- a/arch/s390/include/uapi/asm/Kbuild
+++ b/arch/s390/include/uapi/asm/Kbuild
@@ -44,5 +44,6 @@ header-y += termios.h
 header-y += types.h
 header-y += ucontext.h
 header-y += unistd.h
+header-y += virtio-ccw.h
 header-y += vtoc.h
 header-y += zcrypt.h
diff --git a/arch/s390/include/uapi/asm/virtio-ccw.h b/arch/s390/include/uapi/asm/virtio-ccw.h
new file mode 100644
index 0000000..a9a4ebf
--- /dev/null
+++ b/arch/s390/include/uapi/asm/virtio-ccw.h
@@ -0,0 +1,21 @@
+/*
+ * Definitions for virtio-ccw devices.
+ *
+ * Copyright IBM Corp. 2013
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License (version 2 only)
+ * as published by the Free Software Foundation.
+ *
+ *  Author(s): Cornelia Huck <cornelia.huck@de.ibm.com>
+ */
+#ifndef __KVM_VIRTIO_CCW_H
+#define __KVM_VIRTIO_CCW_H
+
+/* Alignment of vring buffers. */
+#define KVM_VIRTIO_CCW_RING_ALIGN 4096
+
+/* Subcode for diagnose 500 (virtio hypercall). */
+#define KVM_S390_VIRTIO_CCW_NOTIFY 3
+
+#endif
diff --git a/drivers/s390/kvm/virtio_ccw.c b/drivers/s390/kvm/virtio_ccw.c
index 259a2fb..bf5ba3b 100644
--- a/drivers/s390/kvm/virtio_ccw.c
+++ b/drivers/s390/kvm/virtio_ccw.c
@@ -31,6 +31,7 @@
 #include <asm/irq.h>
 #include <asm/cio.h>
 #include <asm/ccwdev.h>
+#include <asm/virtio-ccw.h>
 
 /*
  * virtio related functions
@@ -80,10 +81,6 @@ struct virtio_ccw_vq_info {
 	long cookie;
 };
 
-#define KVM_VIRTIO_CCW_RING_ALIGN 4096
-
-#define KVM_S390_VIRTIO_CCW_NOTIFY 3
-
 #define CCW_CMD_SET_VQ 0x13
 #define CCW_CMD_VDEV_RESET 0x33
 #define CCW_CMD_SET_IND 0x43
-- 
1.7.12.4

[PATCH v4 3/6] KVM: Initialize irqfd from kvm_init().

[Cornelia Huck]

Currently, eventfd introduces module_init/module_exit functions
to initialize/cleanup the irqfd workqueue. This only works, however,
if no other module_init/module_exit functions are built into the
same module.

Let's just move the initialization and cleanup to kvm_init and kvm_exit.
This way, it is also clearer where kvm startup may fail.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
---
 include/linux/kvm_host.h | 13 +++++++++++++
 virt/kvm/eventfd.c       |  7 ++-----
 virt/kvm/kvm_main.c      |  6 ++++++
 3 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 722cae7..3b768ef 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -423,6 +423,19 @@ void kvm_vcpu_uninit(struct kvm_vcpu *vcpu);
 int __must_check vcpu_load(struct kvm_vcpu *vcpu);
 void vcpu_put(struct kvm_vcpu *vcpu);
 
+#ifdef __KVM_HAVE_IOAPIC
+int kvm_irqfd_init(void);
+void kvm_irqfd_exit(void);
+#else
+static inline int kvm_irqfd_init(void)
+{
+	return 0;
+}
+
+static inline void kvm_irqfd_exit(void)
+{
+}
+#endif
 int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align,
 		  struct module *module);
 void kvm_exit(void);
diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
index b6eea5c..f0ced1a 100644
--- a/virt/kvm/eventfd.c
+++ b/virt/kvm/eventfd.c
@@ -544,7 +544,7 @@ void kvm_irq_routing_update(struct kvm *kvm,
  * aggregated from all vm* instances. We need our own isolated single-thread
  * queue to prevent deadlock against flushing the normal work-queue.
  */
-static int __init irqfd_module_init(void)
+int kvm_irqfd_init(void)
 {
 	irqfd_cleanup_wq = create_singlethread_workqueue("kvm-irqfd-cleanup");
 	if (!irqfd_cleanup_wq)
@@ -553,13 +553,10 @@ static int __init irqfd_module_init(void)
 	return 0;
 }
 
-static void __exit irqfd_module_exit(void)
+void kvm_irqfd_exit(void)
 {
 	destroy_workqueue(irqfd_cleanup_wq);
 }
-
-module_init(irqfd_module_init);
-module_exit(irqfd_module_exit);
 #endif
 
 /*
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index adc68fe..7c188a3 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2920,6 +2920,9 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align,
 	int r;
 	int cpu;
 
+	r = kvm_irqfd_init();
+	if (r)
+		goto out_irqfd;
 	r = kvm_arch_init(opaque);
 	if (r)
 		goto out_fail;
@@ -3000,6 +3003,8 @@ out_free_0a:
 out_free_0:
 	kvm_arch_exit();
 out_fail:
+	kvm_irqfd_exit();
+out_irqfd:
 	return r;
 }
 EXPORT_SYMBOL_GPL(kvm_init);
@@ -3016,6 +3021,7 @@ void kvm_exit(void)
 	on_each_cpu(hardware_disable_nolock, NULL, 1);
 	kvm_arch_hardware_unsetup();
 	kvm_arch_exit();
+	kvm_irqfd_exit();
 	free_cpumask_var(cpus_hardware_enabled);
 }
 EXPORT_SYMBOL_GPL(kvm_exit);
-- 
1.7.12.4

[PATCH v4 4/6] KVM: Introduce KVM_VIRTIO_CCW_NOTIFY_BUS.

[Cornelia Huck]

Add a new bus type for virtio-ccw devices on s390.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
---
 include/linux/kvm_host.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 3b768ef..206247f 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -148,6 +148,7 @@ struct kvm_io_bus {
 enum kvm_bus {
 	KVM_MMIO_BUS,
 	KVM_PIO_BUS,
+	KVM_VIRTIO_CCW_NOTIFY_BUS,
 	KVM_NR_BUSES
 };
 
-- 
1.7.12.4

[PATCH v4 5/6] KVM: ioeventfd for virtio-ccw devices.

[Cornelia Huck]

Enhance KVM_IOEVENTFD with a new flag that allows to attach to virtio-ccw
devices on s390 via the KVM_VIRTIO_CCW_NOTIFY_BUS.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
---
 Documentation/virtual/kvm/api.txt |  8 ++++++++
 include/uapi/linux/kvm.h          |  3 +++
 virt/kvm/eventfd.c                | 17 +++++++++++++----
 3 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index c2534c3..86232d6 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -1468,15 +1468,23 @@ struct kvm_ioeventfd {
 	__u8  pad[36];
 };
 
+For the special case of virtio-ccw devices on s390, the ioevent is matched
+to a subchannel/virtqueue tuple instead.
+
 The following flags are defined:
 
 #define KVM_IOEVENTFD_FLAG_DATAMATCH (1 << kvm_ioeventfd_flag_nr_datamatch)
 #define KVM_IOEVENTFD_FLAG_PIO       (1 << kvm_ioeventfd_flag_nr_pio)
 #define KVM_IOEVENTFD_FLAG_DEASSIGN  (1 << kvm_ioeventfd_flag_nr_deassign)
+#define KVM_IOEVENTFD_FLAG_VIRTIO_CCW_NOTIFY \
+	(1 << kvm_ioeventfd_flag_nr_virtio_ccw_notify)
 
 If datamatch flag is set, the event will be signaled only if the written value
 to the registered address is equal to datamatch in struct kvm_ioeventfd.
 
+For virtio-ccw devices, addr contains the subchannel id and datamatch the
+virtqueue index.
+
 
 4.60 KVM_DIRTY_TLB
 
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 9a2db57..8f3e5ae 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -448,12 +448,15 @@ enum {
 	kvm_ioeventfd_flag_nr_datamatch,
 	kvm_ioeventfd_flag_nr_pio,
 	kvm_ioeventfd_flag_nr_deassign,
+	kvm_ioeventfd_flag_nr_virtio_ccw_notify,
 	kvm_ioeventfd_flag_nr_max,
 };
 
 #define KVM_IOEVENTFD_FLAG_DATAMATCH (1 << kvm_ioeventfd_flag_nr_datamatch)
 #define KVM_IOEVENTFD_FLAG_PIO       (1 << kvm_ioeventfd_flag_nr_pio)
 #define KVM_IOEVENTFD_FLAG_DEASSIGN  (1 << kvm_ioeventfd_flag_nr_deassign)
+#define KVM_IOEVENTFD_FLAG_VIRTIO_CCW_NOTIFY \
+	(1 << kvm_ioeventfd_flag_nr_virtio_ccw_notify)
 
 #define KVM_IOEVENTFD_VALID_FLAG_MASK  ((1 << kvm_ioeventfd_flag_nr_max) - 1)
 
diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
index f0ced1a..c9b6494 100644
--- a/virt/kvm/eventfd.c
+++ b/virt/kvm/eventfd.c
@@ -675,15 +675,24 @@ ioeventfd_check_collision(struct kvm *kvm, struct _ioeventfd *p)
 	return false;
 }
 
+static enum kvm_bus ioeventfd_bus_from_flags(__u32 flags)
+{
+	if (flags & KVM_IOEVENTFD_FLAG_PIO)
+		return KVM_PIO_BUS;
+	if (flags & KVM_IOEVENTFD_FLAG_VIRTIO_CCW_NOTIFY)
+		return KVM_VIRTIO_CCW_NOTIFY_BUS;
+	return KVM_MMIO_BUS;
+}
+
 static int
 kvm_assign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
 {
-	int                       pio = args->flags & KVM_IOEVENTFD_FLAG_PIO;
-	enum kvm_bus              bus_idx = pio ? KVM_PIO_BUS : KVM_MMIO_BUS;
+	enum kvm_bus              bus_idx;
 	struct _ioeventfd        *p;
 	struct eventfd_ctx       *eventfd;
 	int                       ret;
 
+	bus_idx = ioeventfd_bus_from_flags(args->flags);
 	/* must be natural-word sized */
 	switch (args->len) {
 	case 1:
@@ -758,12 +767,12 @@ fail:
 static int
 kvm_deassign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
 {
-	int                       pio = args->flags & KVM_IOEVENTFD_FLAG_PIO;
-	enum kvm_bus              bus_idx = pio ? KVM_PIO_BUS : KVM_MMIO_BUS;
+	enum kvm_bus              bus_idx;
 	struct _ioeventfd        *p, *tmp;
 	struct eventfd_ctx       *eventfd;
 	int                       ret = -ENOENT;
 
+	bus_idx = ioeventfd_bus_from_flags(args->flags);
 	eventfd = eventfd_ctx_fdget(args->fd);
 	if (IS_ERR(eventfd))
 		return PTR_ERR(eventfd);
-- 
1.7.12.4

[PATCH v4 6/6] KVM: s390: Wire up ioeventfd.

[Cornelia Huck]

Enable ioeventfd support on s390 and hook up diagnose 500 virtio-ccw
notifications.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
---
 arch/s390/kvm/Kconfig    |  1 +
 arch/s390/kvm/Makefile   |  2 +-
 arch/s390/kvm/diag.c     | 26 ++++++++++++++++++++++++++
 arch/s390/kvm/kvm-s390.c |  1 +
 4 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/arch/s390/kvm/Kconfig b/arch/s390/kvm/Kconfig
index b58dd86..3c43e30 100644
--- a/arch/s390/kvm/Kconfig
+++ b/arch/s390/kvm/Kconfig
@@ -22,6 +22,7 @@ config KVM
 	select PREEMPT_NOTIFIERS
 	select ANON_INODES
 	select HAVE_KVM_CPU_RELAX_INTERCEPT
+	select HAVE_KVM_EVENTFD
 	---help---
 	  Support hosting paravirtualized guest machines using the SIE
 	  virtualization capability on the mainframe. This should work
diff --git a/arch/s390/kvm/Makefile b/arch/s390/kvm/Makefile
index 3975722..8fe9d65 100644
--- a/arch/s390/kvm/Makefile
+++ b/arch/s390/kvm/Makefile
@@ -6,7 +6,7 @@
 # it under the terms of the GNU General Public License (version 2 only)
 # as published by the Free Software Foundation.
 
-common-objs = $(addprefix ../../../virt/kvm/, kvm_main.o)
+common-objs = $(addprefix ../../../virt/kvm/, kvm_main.o eventfd.o)
 
 ccflags-y := -Ivirt/kvm -Iarch/s390/kvm
 
diff --git a/arch/s390/kvm/diag.c b/arch/s390/kvm/diag.c
index a390687..96907f2 100644
--- a/arch/s390/kvm/diag.c
+++ b/arch/s390/kvm/diag.c
@@ -13,6 +13,7 @@
 
 #include <linux/kvm.h>
 #include <linux/kvm_host.h>
+#include <asm/virtio-ccw.h>
 #include "kvm-s390.h"
 #include "trace.h"
 #include "trace-s390.h"
@@ -104,6 +105,29 @@ static int __diag_ipl_functions(struct kvm_vcpu *vcpu)
 	return -EREMOTE;
 }
 
+static int __diag_virtio_hypercall(struct kvm_vcpu *vcpu)
+{
+	int ret, idx;
+
+	/* No virtio-ccw notification? Get out quickly. */
+	if (!vcpu->kvm->arch.css_support ||
+	    (vcpu->run->s.regs.gprs[1] != KVM_S390_VIRTIO_CCW_NOTIFY))
+		return -EOPNOTSUPP;
+
+	idx = srcu_read_lock(&vcpu->kvm->srcu);
+	/*
+	 * The layout is as follows:
+	 * - gpr 2 contains the subchannel id (passed as addr)
+	 * - gpr 3 contains the virtqueue index (passed as datamatch)
+	 */
+	ret = kvm_io_bus_write(vcpu->kvm, KVM_VIRTIO_CCW_NOTIFY_BUS,
+				vcpu->run->s.regs.gprs[2],
+				8, &vcpu->run->s.regs.gprs[3]);
+	srcu_read_unlock(&vcpu->kvm->srcu, idx);
+	/* kvm_io_bus_write returns -EOPNOTSUPP if it found no match. */
+	return ret;
+}
+
 int kvm_s390_handle_diag(struct kvm_vcpu *vcpu)
 {
 	int code = (vcpu->arch.sie_block->ipb & 0xfff0000) >> 16;
@@ -118,6 +142,8 @@ int kvm_s390_handle_diag(struct kvm_vcpu *vcpu)
 		return __diag_time_slice_end_directed(vcpu);
 	case 0x308:
 		return __diag_ipl_functions(vcpu);
+	case 0x500:
+		return __diag_virtio_hypercall(vcpu);
 	default:
 		return -EOPNOTSUPP;
 	}
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index f822d36..04d2454 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -142,6 +142,7 @@ int kvm_dev_ioctl_check_extension(long ext)
 	case KVM_CAP_ONE_REG:
 	case KVM_CAP_ENABLE_CAP:
 	case KVM_CAP_S390_CSS_SUPPORT:
+	case KVM_CAP_IOEVENTFD:
 		r = 1;
 		break;
 	case KVM_CAP_NR_VCPUS:
-- 
1.7.12.4

Re: [PATCH v4 6/6] KVM: s390: Wire up ioeventfd.

[Michael S. Tsirkin]

On Thu, Feb 28, 2013 at 10:22:32AM +0100, Cornelia Huck wrote:
> Enable ioeventfd support on s390 and hook up diagnose 500 virtio-ccw
> notifications.
> 
> Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
> ---
>  arch/s390/kvm/Kconfig    |  1 +
>  arch/s390/kvm/Makefile   |  2 +-
>  arch/s390/kvm/diag.c     | 26 ++++++++++++++++++++++++++
>  arch/s390/kvm/kvm-s390.c |  1 +
>  4 files changed, 29 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/s390/kvm/Kconfig b/arch/s390/kvm/Kconfig
> index b58dd86..3c43e30 100644
> --- a/arch/s390/kvm/Kconfig
> +++ b/arch/s390/kvm/Kconfig
> @@ -22,6 +22,7 @@ config KVM
>  	select PREEMPT_NOTIFIERS
>  	select ANON_INODES
>  	select HAVE_KVM_CPU_RELAX_INTERCEPT
> +	select HAVE_KVM_EVENTFD
>  	---help---
>  	  Support hosting paravirtualized guest machines using the SIE
>  	  virtualization capability on the mainframe. This should work
> diff --git a/arch/s390/kvm/Makefile b/arch/s390/kvm/Makefile
> index 3975722..8fe9d65 100644
> --- a/arch/s390/kvm/Makefile
> +++ b/arch/s390/kvm/Makefile
> @@ -6,7 +6,7 @@
>  # it under the terms of the GNU General Public License (version 2 only)
>  # as published by the Free Software Foundation.
>  
> -common-objs = $(addprefix ../../../virt/kvm/, kvm_main.o)
> +common-objs = $(addprefix ../../../virt/kvm/, kvm_main.o eventfd.o)
>  
>  ccflags-y := -Ivirt/kvm -Iarch/s390/kvm
>  
> diff --git a/arch/s390/kvm/diag.c b/arch/s390/kvm/diag.c
> index a390687..96907f2 100644
> --- a/arch/s390/kvm/diag.c
> +++ b/arch/s390/kvm/diag.c
> @@ -13,6 +13,7 @@
>  
>  #include <linux/kvm.h>
>  #include <linux/kvm_host.h>
> +#include <asm/virtio-ccw.h>
>  #include "kvm-s390.h"
>  #include "trace.h"
>  #include "trace-s390.h"
> @@ -104,6 +105,29 @@ static int __diag_ipl_functions(struct kvm_vcpu *vcpu)
>  	return -EREMOTE;
>  }
>  
> +static int __diag_virtio_hypercall(struct kvm_vcpu *vcpu)
> +{
> +	int ret, idx;
> +
> +	/* No virtio-ccw notification? Get out quickly. */
> +	if (!vcpu->kvm->arch.css_support ||
> +	    (vcpu->run->s.regs.gprs[1] != KVM_S390_VIRTIO_CCW_NOTIFY))
> +		return -EOPNOTSUPP;
> +
> +	idx = srcu_read_lock(&vcpu->kvm->srcu);
> +	/*
> +	 * The layout is as follows:
> +	 * - gpr 2 contains the subchannel id (passed as addr)
> +	 * - gpr 3 contains the virtqueue index (passed as datamatch)
> +	 */
> +	ret = kvm_io_bus_write(vcpu->kvm, KVM_VIRTIO_CCW_NOTIFY_BUS,
> +				vcpu->run->s.regs.gprs[2],
> +				8, &vcpu->run->s.regs.gprs[3]);
> +	srcu_read_unlock(&vcpu->kvm->srcu, idx);
> +	/* kvm_io_bus_write returns -EOPNOTSUPP if it found no match. */
> +	return ret;

Yes but it returns 8 on success. You probably want 0. So:
	return ret < 0 ? ret : 0;

> +}
> +
>  int kvm_s390_handle_diag(struct kvm_vcpu *vcpu)
>  {
>  	int code = (vcpu->arch.sie_block->ipb & 0xfff0000) >> 16;
> @@ -118,6 +142,8 @@ int kvm_s390_handle_diag(struct kvm_vcpu *vcpu)
>  		return __diag_time_slice_end_directed(vcpu);
>  	case 0x308:
>  		return __diag_ipl_functions(vcpu);
> +	case 0x500:
> +		return __diag_virtio_hypercall(vcpu);
>  	default:
>  		return -EOPNOTSUPP;
>  	}
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index f822d36..04d2454 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -142,6 +142,7 @@ int kvm_dev_ioctl_check_extension(long ext)
>  	case KVM_CAP_ONE_REG:
>  	case KVM_CAP_ENABLE_CAP:
>  	case KVM_CAP_S390_CSS_SUPPORT:
> +	case KVM_CAP_IOEVENTFD:
>  		r = 1;
>  		break;
>  	case KVM_CAP_NR_VCPUS:
> -- 
> 1.7.12.4

Re: [PATCH v4 6/6] KVM: s390: Wire up ioeventfd.

[Cornelia Huck]

On Thu, 28 Feb 2013 11:50:45 +0200
"Michael S. Tsirkin" <mst@redhat.com> wrote:

> On Thu, Feb 28, 2013 at 10:22:32AM +0100, Cornelia Huck wrote:
> > Enable ioeventfd support on s390 and hook up diagnose 500 virtio-ccw
> > notifications.
> > 
> > Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
> > ---
> >  arch/s390/kvm/Kconfig    |  1 +
> >  arch/s390/kvm/Makefile   |  2 +-
> >  arch/s390/kvm/diag.c     | 26 ++++++++++++++++++++++++++
> >  arch/s390/kvm/kvm-s390.c |  1 +
> >  4 files changed, 29 insertions(+), 1 deletion(-)
> > 
> > diff --git a/arch/s390/kvm/Kconfig b/arch/s390/kvm/Kconfig
> > index b58dd86..3c43e30 100644
> > --- a/arch/s390/kvm/Kconfig
> > +++ b/arch/s390/kvm/Kconfig
> > @@ -22,6 +22,7 @@ config KVM
> >  	select PREEMPT_NOTIFIERS
> >  	select ANON_INODES
> >  	select HAVE_KVM_CPU_RELAX_INTERCEPT
> > +	select HAVE_KVM_EVENTFD
> >  	---help---
> >  	  Support hosting paravirtualized guest machines using the SIE
> >  	  virtualization capability on the mainframe. This should work
> > diff --git a/arch/s390/kvm/Makefile b/arch/s390/kvm/Makefile
> > index 3975722..8fe9d65 100644
> > --- a/arch/s390/kvm/Makefile
> > +++ b/arch/s390/kvm/Makefile
> > @@ -6,7 +6,7 @@
> >  # it under the terms of the GNU General Public License (version 2 only)
> >  # as published by the Free Software Foundation.
> >  
> > -common-objs = $(addprefix ../../../virt/kvm/, kvm_main.o)
> > +common-objs = $(addprefix ../../../virt/kvm/, kvm_main.o eventfd.o)
> >  
> >  ccflags-y := -Ivirt/kvm -Iarch/s390/kvm
> >  
> > diff --git a/arch/s390/kvm/diag.c b/arch/s390/kvm/diag.c
> > index a390687..96907f2 100644
> > --- a/arch/s390/kvm/diag.c
> > +++ b/arch/s390/kvm/diag.c
> > @@ -13,6 +13,7 @@
> >  
> >  #include <linux/kvm.h>
> >  #include <linux/kvm_host.h>
> > +#include <asm/virtio-ccw.h>
> >  #include "kvm-s390.h"
> >  #include "trace.h"
> >  #include "trace-s390.h"
> > @@ -104,6 +105,29 @@ static int __diag_ipl_functions(struct kvm_vcpu *vcpu)
> >  	return -EREMOTE;
> >  }
> >  
> > +static int __diag_virtio_hypercall(struct kvm_vcpu *vcpu)
> > +{
> > +	int ret, idx;
> > +
> > +	/* No virtio-ccw notification? Get out quickly. */
> > +	if (!vcpu->kvm->arch.css_support ||
> > +	    (vcpu->run->s.regs.gprs[1] != KVM_S390_VIRTIO_CCW_NOTIFY))
> > +		return -EOPNOTSUPP;
> > +
> > +	idx = srcu_read_lock(&vcpu->kvm->srcu);
> > +	/*
> > +	 * The layout is as follows:
> > +	 * - gpr 2 contains the subchannel id (passed as addr)
> > +	 * - gpr 3 contains the virtqueue index (passed as datamatch)
> > +	 */
> > +	ret = kvm_io_bus_write(vcpu->kvm, KVM_VIRTIO_CCW_NOTIFY_BUS,
> > +				vcpu->run->s.regs.gprs[2],
> > +				8, &vcpu->run->s.regs.gprs[3]);
> > +	srcu_read_unlock(&vcpu->kvm->srcu, idx);
> > +	/* kvm_io_bus_write returns -EOPNOTSUPP if it found no match. */
> > +	return ret;
> 
> Yes but it returns 8 on success. You probably want 0. So:
> 	return ret < 0 ? ret : 0;

Whoops. Doesn't seem to have hurt, though.

v6 will come up shortly.

> 
> > +}
> > +
> >  int kvm_s390_handle_diag(struct kvm_vcpu *vcpu)
> >  {
> >  	int code = (vcpu->arch.sie_block->ipb & 0xfff0000) >> 16;
> > @@ -118,6 +142,8 @@ int kvm_s390_handle_diag(struct kvm_vcpu *vcpu)
> >  		return __diag_time_slice_end_directed(vcpu);
> >  	case 0x308:
> >  		return __diag_ipl_functions(vcpu);
> > +	case 0x500:
> > +		return __diag_virtio_hypercall(vcpu);
> >  	default:
> >  		return -EOPNOTSUPP;
> >  	}
> > diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> > index f822d36..04d2454 100644
> > --- a/arch/s390/kvm/kvm-s390.c
> > +++ b/arch/s390/kvm/kvm-s390.c
> > @@ -142,6 +142,7 @@ int kvm_dev_ioctl_check_extension(long ext)
> >  	case KVM_CAP_ONE_REG:
> >  	case KVM_CAP_ENABLE_CAP:
> >  	case KVM_CAP_S390_CSS_SUPPORT:
> > +	case KVM_CAP_IOEVENTFD:
> >  		r = 1;
> >  		break;
> >  	case KVM_CAP_NR_VCPUS:
> > -- 
> > 1.7.12.4
> 

Re: [PATCH v4 6/6] KVM: s390: Wire up ioeventfd.

[Gleb Natapov]

On Thu, Feb 28, 2013 at 11:20:13AM +0100, Cornelia Huck wrote:
> Whoops. Doesn't seem to have hurt, though.
> 
> v6 will come up shortly.
> 
Are you going to skip v5?

--
			Gleb.

Re: [PATCH v4 6/6] KVM: s390: Wire up ioeventfd.

[Cornelia Huck]

On Thu, 28 Feb 2013 12:24:19 +0200
Gleb Natapov <gleb@redhat.com> wrote:

> On Thu, Feb 28, 2013 at 11:20:13AM +0100, Cornelia Huck wrote:
> > Whoops. Doesn't seem to have hurt, though.
> > 
> > v6 will come up shortly.
> > 
> Are you going to skip v5?
> 
> --
> 			Gleb.
> 

I meant v5 (-ENOCOFFEE).

Re: [PATCH v4 3/6] KVM: Initialize irqfd from kvm_init().

[Sasha Levin]

On 02/28/2013 04:22 AM, Cornelia Huck wrote:
> Currently, eventfd introduces module_init/module_exit functions
> to initialize/cleanup the irqfd workqueue. This only works, however,
> if no other module_init/module_exit functions are built into the
> same module.
> 
> Let's just move the initialization and cleanup to kvm_init and kvm_exit.
> This way, it is also clearer where kvm startup may fail.
> 
> Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>

I'm seeing this during boot:

[    6.763302] ------------[ cut here ]------------
[    6.763763] WARNING: at kernel/workqueue.c:4204 destroy_workqueue+0x1df/0x3d0()
[    6.764507] Modules linked in:
[    6.764792] Pid: 1, comm: swapper/0 Tainted: G        W    3.9.0-rc5-next-20130402-sasha-00015-g3522ec5 #324
[    6.765654] Call Trace:
[    6.765875]  [<ffffffff811074fb>] warn_slowpath_common+0x8b/0xc0
[    6.766436]  [<ffffffff81107545>] warn_slowpath_null+0x15/0x20
[    6.766947]  [<ffffffff8112ca7f>] destroy_workqueue+0x1df/0x3d0
[    6.768631]  [<ffffffff8100d880>] kvm_irqfd_exit+0x10/0x20
[    6.770000]  [<ffffffff81004dbb>] kvm_init+0x2ab/0x310
[    6.770607]  [<ffffffff86183dc0>] ? cpu_has_kvm_support+0x4d/0x4d
[    6.771241]  [<ffffffff86183fb4>] vmx_init+0x1f4/0x437
[    6.771709]  [<ffffffff86183dc0>] ? cpu_has_kvm_support+0x4d/0x4d
[    6.772266]  [<ffffffff810020f2>] do_one_initcall+0xb2/0x1b0
[    6.772995]  [<ffffffff86180021>] kernel_init_freeable+0x15d/0x1ef
[    6.773857]  [<ffffffff8617f801>] ? loglevel+0x31/0x31
[    6.774609]  [<ffffffff83d51230>] ? rest_init+0x140/0x140
[    6.775551]  [<ffffffff83d51239>] kernel_init+0x9/0xf0
[    6.776162]  [<ffffffff83dbf37c>] ret_from_fork+0x7c/0xb0
[    6.776662]  [<ffffffff83d51230>] ? rest_init+0x140/0x140
[    6.777241] ---[ end trace 10bba684ced4346a ]---

And I think it has something to do with this patch.


Thanks,
Sasha

Re: [Qemu-devel] [PATCH v4 3/6] KVM: Initialize irqfd from kvm_init().

[Sasha Levin]

On 02/28/2013 04:22 AM, Cornelia Huck wrote:
> Currently, eventfd introduces module_init/module_exit functions
> to initialize/cleanup the irqfd workqueue. This only works, however,
> if no other module_init/module_exit functions are built into the
> same module.
> 
> Let's just move the initialization and cleanup to kvm_init and kvm_exit.
> This way, it is also clearer where kvm startup may fail.
> 
> Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>

I'm seeing this during boot:

[    6.763302] ------------[ cut here ]------------
[    6.763763] WARNING: at kernel/workqueue.c:4204 destroy_workqueue+0x1df/0x3d0()
[    6.764507] Modules linked in:
[    6.764792] Pid: 1, comm: swapper/0 Tainted: G        W    3.9.0-rc5-next-20130402-sasha-00015-g3522ec5 #324
[    6.765654] Call Trace:
[    6.765875]  [<ffffffff811074fb>] warn_slowpath_common+0x8b/0xc0
[    6.766436]  [<ffffffff81107545>] warn_slowpath_null+0x15/0x20
[    6.766947]  [<ffffffff8112ca7f>] destroy_workqueue+0x1df/0x3d0
[    6.768631]  [<ffffffff8100d880>] kvm_irqfd_exit+0x10/0x20
[    6.770000]  [<ffffffff81004dbb>] kvm_init+0x2ab/0x310
[    6.770607]  [<ffffffff86183dc0>] ? cpu_has_kvm_support+0x4d/0x4d
[    6.771241]  [<ffffffff86183fb4>] vmx_init+0x1f4/0x437
[    6.771709]  [<ffffffff86183dc0>] ? cpu_has_kvm_support+0x4d/0x4d
[    6.772266]  [<ffffffff810020f2>] do_one_initcall+0xb2/0x1b0
[    6.772995]  [<ffffffff86180021>] kernel_init_freeable+0x15d/0x1ef
[    6.773857]  [<ffffffff8617f801>] ? loglevel+0x31/0x31
[    6.774609]  [<ffffffff83d51230>] ? rest_init+0x140/0x140
[    6.775551]  [<ffffffff83d51239>] kernel_init+0x9/0xf0
[    6.776162]  [<ffffffff83dbf37c>] ret_from_fork+0x7c/0xb0
[    6.776662]  [<ffffffff83d51230>] ? rest_init+0x140/0x140
[    6.777241] ---[ end trace 10bba684ced4346a ]---

And I think it has something to do with this patch.


Thanks,
Sasha

Re: [PATCH v4 3/6] KVM: Initialize irqfd from kvm_init().

[Cornelia Huck]

On Tue, 02 Apr 2013 20:40:53 -0400
Sasha Levin <sasha.levin@oracle.com> wrote:

> On 02/28/2013 04:22 AM, Cornelia Huck wrote:
> > Currently, eventfd introduces module_init/module_exit functions
> > to initialize/cleanup the irqfd workqueue. This only works, however,
> > if no other module_init/module_exit functions are built into the
> > same module.
> > 
> > Let's just move the initialization and cleanup to kvm_init and kvm_exit.
> > This way, it is also clearer where kvm startup may fail.
> > 
> > Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
> 
> I'm seeing this during boot:
> 
> [    6.763302] ------------[ cut here ]------------
> [    6.763763] WARNING: at kernel/workqueue.c:4204 destroy_workqueue+0x1df/0x3d0()
> [    6.764507] Modules linked in:
> [    6.764792] Pid: 1, comm: swapper/0 Tainted: G        W    3.9.0-rc5-next-20130402-sasha-00015-g3522ec5 #324
> [    6.765654] Call Trace:
> [    6.765875]  [<ffffffff811074fb>] warn_slowpath_common+0x8b/0xc0
> [    6.766436]  [<ffffffff81107545>] warn_slowpath_null+0x15/0x20
> [    6.766947]  [<ffffffff8112ca7f>] destroy_workqueue+0x1df/0x3d0
> [    6.768631]  [<ffffffff8100d880>] kvm_irqfd_exit+0x10/0x20
> [    6.770000]  [<ffffffff81004dbb>] kvm_init+0x2ab/0x310
> [    6.770607]  [<ffffffff86183dc0>] ? cpu_has_kvm_support+0x4d/0x4d
> [    6.771241]  [<ffffffff86183fb4>] vmx_init+0x1f4/0x437
> [    6.771709]  [<ffffffff86183dc0>] ? cpu_has_kvm_support+0x4d/0x4d
> [    6.772266]  [<ffffffff810020f2>] do_one_initcall+0xb2/0x1b0
> [    6.772995]  [<ffffffff86180021>] kernel_init_freeable+0x15d/0x1ef
> [    6.773857]  [<ffffffff8617f801>] ? loglevel+0x31/0x31
> [    6.774609]  [<ffffffff83d51230>] ? rest_init+0x140/0x140
> [    6.775551]  [<ffffffff83d51239>] kernel_init+0x9/0xf0
> [    6.776162]  [<ffffffff83dbf37c>] ret_from_fork+0x7c/0xb0
> [    6.776662]  [<ffffffff83d51230>] ? rest_init+0x140/0x140
> [    6.777241] ---[ end trace 10bba684ced4346a ]---
> 
> And I think it has something to do with this patch.

What this patch does is move initialization of the workqueue - the code
called should be indentical.

The workqueue created/destroyed should not have been touched (no irqfds
yet), but the new workqueue code seems to encounter something
unexpected.

I'd expect destroy_workqueue() to be callable after a successful
create_singlethread_workqueue(). Tejun?

> 
> 
> Thanks,
> Sasha
> 

Re: [Qemu-devel] [PATCH v4 3/6] KVM: Initialize irqfd from kvm_init().

[Cornelia Huck]

On Tue, 02 Apr 2013 20:40:53 -0400
Sasha Levin <sasha.levin@oracle.com> wrote:

> On 02/28/2013 04:22 AM, Cornelia Huck wrote:
> > Currently, eventfd introduces module_init/module_exit functions
> > to initialize/cleanup the irqfd workqueue. This only works, however,
> > if no other module_init/module_exit functions are built into the
> > same module.
> > 
> > Let's just move the initialization and cleanup to kvm_init and kvm_exit.
> > This way, it is also clearer where kvm startup may fail.
> > 
> > Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
> 
> I'm seeing this during boot:
> 
> [    6.763302] ------------[ cut here ]------------
> [    6.763763] WARNING: at kernel/workqueue.c:4204 destroy_workqueue+0x1df/0x3d0()
> [    6.764507] Modules linked in:
> [    6.764792] Pid: 1, comm: swapper/0 Tainted: G        W    3.9.0-rc5-next-20130402-sasha-00015-g3522ec5 #324
> [    6.765654] Call Trace:
> [    6.765875]  [<ffffffff811074fb>] warn_slowpath_common+0x8b/0xc0
> [    6.766436]  [<ffffffff81107545>] warn_slowpath_null+0x15/0x20
> [    6.766947]  [<ffffffff8112ca7f>] destroy_workqueue+0x1df/0x3d0
> [    6.768631]  [<ffffffff8100d880>] kvm_irqfd_exit+0x10/0x20
> [    6.770000]  [<ffffffff81004dbb>] kvm_init+0x2ab/0x310
> [    6.770607]  [<ffffffff86183dc0>] ? cpu_has_kvm_support+0x4d/0x4d
> [    6.771241]  [<ffffffff86183fb4>] vmx_init+0x1f4/0x437
> [    6.771709]  [<ffffffff86183dc0>] ? cpu_has_kvm_support+0x4d/0x4d
> [    6.772266]  [<ffffffff810020f2>] do_one_initcall+0xb2/0x1b0
> [    6.772995]  [<ffffffff86180021>] kernel_init_freeable+0x15d/0x1ef
> [    6.773857]  [<ffffffff8617f801>] ? loglevel+0x31/0x31
> [    6.774609]  [<ffffffff83d51230>] ? rest_init+0x140/0x140
> [    6.775551]  [<ffffffff83d51239>] kernel_init+0x9/0xf0
> [    6.776162]  [<ffffffff83dbf37c>] ret_from_fork+0x7c/0xb0
> [    6.776662]  [<ffffffff83d51230>] ? rest_init+0x140/0x140
> [    6.777241] ---[ end trace 10bba684ced4346a ]---
> 
> And I think it has something to do with this patch.

What this patch does is move initialization of the workqueue - the code
called should be indentical.

The workqueue created/destroyed should not have been touched (no irqfds
yet), but the new workqueue code seems to encounter something
unexpected.

I'd expect destroy_workqueue() to be callable after a successful
create_singlethread_workqueue(). Tejun?

> 
> 
> Thanks,
> Sasha
>