From d7ead0c3c27ef601964d1428066fac932070af7f Mon Sep 17 00:00:00 2001 From: Aurelien Chartier Date: Tue, 9 Jul 2013 14:29:35 +0100 Subject: [PATCH 1/5] xenbus: frontend resume cleanup Only create the delayed resume workqueue if we are running in the same domain as xenstored and issue a warning if the workqueue creation fails. Move the work initialization to the device probe so it is done only once. Signed-off-by: Aurelien Chartier Signed-off-by: Konrad Rzeszutek Wilk Reviewed-by: David Vrabel --- drivers/xen/xenbus/xenbus_probe_frontend.c | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) diff --git a/drivers/xen/xenbus/xenbus_probe_frontend.c b/drivers/xen/xenbus/xenbus_probe_frontend.c index 6ed8a9df4472..34b20bfa4e8c 100644 --- a/drivers/xen/xenbus/xenbus_probe_frontend.c +++ b/drivers/xen/xenbus/xenbus_probe_frontend.c @@ -115,7 +115,6 @@ static int xenbus_frontend_dev_resume(struct device *dev) return -EFAULT; } - INIT_WORK(&xdev->work, xenbus_frontend_delayed_resume); queue_work(xenbus_frontend_wq, &xdev->work); return 0; @@ -124,6 +123,16 @@ static int xenbus_frontend_dev_resume(struct device *dev) return xenbus_dev_resume(dev); } +static int xenbus_frontend_dev_probe(struct device *dev) +{ + if (xen_store_domain_type == XS_LOCAL) { + struct xenbus_device *xdev = to_xenbus_device(dev); + INIT_WORK(&xdev->work, xenbus_frontend_delayed_resume); + } + + return xenbus_dev_probe(dev); +} + static const struct dev_pm_ops xenbus_pm_ops = { .suspend = xenbus_dev_suspend, .resume = xenbus_frontend_dev_resume, @@ -142,7 +151,7 @@ static struct xen_bus_type xenbus_frontend = { .name = "xen", .match = xenbus_match, .uevent = xenbus_uevent_frontend, - .probe = xenbus_dev_probe, + .probe = xenbus_frontend_dev_probe, .remove = xenbus_dev_remove, .shutdown = xenbus_dev_shutdown, .dev_attrs = xenbus_dev_attrs, @@ -474,7 +483,11 @@ static int __init xenbus_probe_frontend_init(void) register_xenstore_notifier(&xenstore_notifier); - xenbus_frontend_wq = create_workqueue("xenbus_frontend"); + if (xen_store_domain_type == XS_LOCAL) { + xenbus_frontend_wq = create_workqueue("xenbus_frontend"); + if (!xenbus_frontend_wq) + pr_warn("create xenbus frontend workqueue failed, S3 resume is likely to fail\n"); + } return 0; } From f21407179ccd0dec35f4580052c26ea923c28ac9 Mon Sep 17 00:00:00 2001 From: Julien Grall Date: Mon, 22 Jul 2013 22:40:58 +0100 Subject: [PATCH 2/5] xen/arm64: Don't compile cpu hotplug On ARM64, when CONFIG_XEN=y, the compilation will fail because CPU hotplug is not yet supported with XEN. For now, disable it. Signed-off-by: Julien Grall Signed-off-by: Konrad Rzeszutek Wilk Acked-by: Mark Rutland --- drivers/xen/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile index eabd0ee1c2bc..fc37c49a8ffe 100644 --- a/drivers/xen/Makefile +++ b/drivers/xen/Makefile @@ -1,4 +1,4 @@ -ifneq ($(CONFIG_ARM),y) +ifeq ($(filter y, $(CONFIG_ARM) $(CONFIG_ARM64)),) obj-y += manage.o obj-$(CONFIG_HOTPLUG_CPU) += cpu_hotplug.o endif From 9e7fd145b691127cfd48ab8c05cc1aa6d35b57ad Mon Sep 17 00:00:00 2001 From: Julien Grall Date: Tue, 23 Jul 2013 16:21:28 +0100 Subject: [PATCH 3/5] xen/arm: enable PV control for ARM Enable lifecyle management (reboot, shutdown...) from the toolstack for ARM guests. Signed-off-by: Julien Grall Signed-off-by: Konrad Rzeszutek Wilk Acked-by: Stefano Stabellini --- drivers/xen/Makefile | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile index fc37c49a8ffe..14fe79d8634a 100644 --- a/drivers/xen/Makefile +++ b/drivers/xen/Makefile @@ -1,9 +1,8 @@ ifeq ($(filter y, $(CONFIG_ARM) $(CONFIG_ARM64)),) -obj-y += manage.o obj-$(CONFIG_HOTPLUG_CPU) += cpu_hotplug.o endif obj-$(CONFIG_X86) += fallback.o -obj-y += grant-table.o features.o events.o balloon.o +obj-y += grant-table.o features.o events.o balloon.o manage.o obj-y += xenbus/ nostackp := $(call cc-option, -fno-stack-protector) From 179fbd5a45f0d4034cc6fd37b8d367a3b79663c4 Mon Sep 17 00:00:00 2001 From: David Vrabel Date: Fri, 19 Jul 2013 15:51:58 +0100 Subject: [PATCH 4/5] xen/evtchn: avoid a deadlock when unbinding an event channel Unbinding an event channel (either with the ioctl or when the evtchn device is closed) may deadlock because disable_irq() is called with port_user_lock held which is also locked by the interrupt handler. Think of the IOCTL_EVTCHN_UNBIND is being serviced, the routine has just taken the lock, and an interrupt happens. The evtchn_interrupt is invoked, tries to take the lock and spins forever. A quick glance at the code shows that the spinlock is a local IRQ variant. Unfortunately that does not help as "disable_irq() waits for the interrupt handler on all CPUs to stop running. If the irq occurs on another VCPU, it tries to take port_user_lock and can't because the unbind ioctl is holding it." (from David). Hence we cannot depend on the said spinlock to protect us. We could make it a system wide IRQ disable spinlock but there is a better way. We can piggyback on the fact that the existence of the spinlock is to make get_port_user() checks be up-to-date. And we can alter those checks to not depend on the spin lock (as it's protected by u->bind_mutex in the ioctl) and can remove the unnecessary locking (this is IOCTL_EVTCHN_UNBIND) path. In the interrupt handler we cannot use the mutex, but we do not need it. "The unbind disables the irq before making the port user stale, so when you clear it you are guaranteed that the interrupt handler that might use that port cannot be running." (from David). Hence this patch removes the spinlock usage on the teardown path and piggybacks on disable_irq happening before we muck with the get_port_user() data. This ensures that the interrupt handler will never run on stale data. Signed-off-by: David Vrabel Signed-off-by: Konrad Rzeszutek Wilk [v1: Expanded the commit description a bit] --- drivers/xen/evtchn.c | 21 ++------------------- 1 file changed, 2 insertions(+), 19 deletions(-) diff --git a/drivers/xen/evtchn.c b/drivers/xen/evtchn.c index 8feecf01d55c..b6165e047f48 100644 --- a/drivers/xen/evtchn.c +++ b/drivers/xen/evtchn.c @@ -379,18 +379,12 @@ static long evtchn_ioctl(struct file *file, if (unbind.port >= NR_EVENT_CHANNELS) break; - spin_lock_irq(&port_user_lock); - rc = -ENOTCONN; - if (get_port_user(unbind.port) != u) { - spin_unlock_irq(&port_user_lock); + if (get_port_user(unbind.port) != u) break; - } disable_irq(irq_from_evtchn(unbind.port)); - spin_unlock_irq(&port_user_lock); - evtchn_unbind_from_user(u, unbind.port); rc = 0; @@ -490,26 +484,15 @@ static int evtchn_release(struct inode *inode, struct file *filp) int i; struct per_user_data *u = filp->private_data; - spin_lock_irq(&port_user_lock); - - free_page((unsigned long)u->ring); - for (i = 0; i < NR_EVENT_CHANNELS; i++) { if (get_port_user(i) != u) continue; disable_irq(irq_from_evtchn(i)); - } - - spin_unlock_irq(&port_user_lock); - - for (i = 0; i < NR_EVENT_CHANNELS; i++) { - if (get_port_user(i) != u) - continue; - evtchn_unbind_from_user(get_port_user(i), i); } + free_page((unsigned long)u->ring); kfree(u->name); kfree(u); From 741ddbcfd26f192b0677961385b599aa785f8119 Mon Sep 17 00:00:00 2001 From: Stefano Stabellini Date: Tue, 23 Jul 2013 17:46:58 +0100 Subject: [PATCH 5/5] xen/tmem: do not allow XEN_TMEM on ARM64 tmem is not supported on arm or arm64 yet. Will revert this once the Xen hypervisor supports it. Signed-off-by: Stefano Stabellini Signed-off-by: Konrad Rzeszutek Wilk --- drivers/xen/Kconfig | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig index 9e02d60a364b..23eae5cb69c2 100644 --- a/drivers/xen/Kconfig +++ b/drivers/xen/Kconfig @@ -145,7 +145,7 @@ config SWIOTLB_XEN config XEN_TMEM tristate - depends on !ARM + depends on !ARM && !ARM64 default m if (CLEANCACHE || FRONTSWAP) help Shim to interface in-kernel Transcendent Memory hooks