From aac8a70db24bd3916b9ddce1761e500771356b6b Mon Sep 17 00:00:00 2001 From: SeongJae Park Date: Wed, 23 Sep 2020 08:18:39 +0200 Subject: [PATCH 1/8] xen-blkback: add a parameter for disabling of persistent grants MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Persistent grants feature provides high scalability. On some small systems, however, it could incur data copy overheads[1] and thus it is required to be disabled. But, there is no option to disable it. For the reason, this commit adds a module parameter for disabling of the feature. [1] https://wiki.xen.org/wiki/Xen_4.3_Block_Protocol_Scalability Signed-off-by: Anthony Liguori Signed-off-by: SeongJae Park Reviewed-by: Juergen Gross Acked-by: Roger Pau Monné Link: https://lore.kernel.org/r/20200923061841.20531-2-sjpark@amazon.com Signed-off-by: Boris Ostrovsky --- .../ABI/testing/sysfs-driver-xen-blkback | 9 ++++++++ drivers/block/xen-blkback/xenbus.c | 22 ++++++++++++++----- 2 files changed, 25 insertions(+), 6 deletions(-) diff --git a/Documentation/ABI/testing/sysfs-driver-xen-blkback b/Documentation/ABI/testing/sysfs-driver-xen-blkback index ecb7942ff146..ac2947b98950 100644 --- a/Documentation/ABI/testing/sysfs-driver-xen-blkback +++ b/Documentation/ABI/testing/sysfs-driver-xen-blkback @@ -35,3 +35,12 @@ Description: controls the duration in milliseconds that blkback will not cache any page not backed by a grant mapping. The default is 10ms. + +What: /sys/module/xen_blkback/parameters/feature_persistent +Date: September 2020 +KernelVersion: 5.10 +Contact: SeongJae Park +Description: + Whether to enable the persistent grants feature or not. Note + that this option only takes effect on newly created backends. + The default is Y (enable). diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c index 5e7c36d73dc6..f5705569e2a7 100644 --- a/drivers/block/xen-blkback/xenbus.c +++ b/drivers/block/xen-blkback/xenbus.c @@ -473,6 +473,12 @@ static void xen_vbd_free(struct xen_vbd *vbd) vbd->bdev = NULL; } +/* Enable the persistent grants feature. */ +static bool feature_persistent = true; +module_param(feature_persistent, bool, 0644); +MODULE_PARM_DESC(feature_persistent, + "Enables the persistent grants feature"); + static int xen_vbd_create(struct xen_blkif *blkif, blkif_vdev_t handle, unsigned major, unsigned minor, int readonly, int cdrom) @@ -518,6 +524,8 @@ static int xen_vbd_create(struct xen_blkif *blkif, blkif_vdev_t handle, if (q && blk_queue_secure_erase(q)) vbd->discard_secure = true; + vbd->feature_gnt_persistent = feature_persistent; + pr_debug("Successful creation of handle=%04x (dom=%u)\n", handle, blkif->domid); return 0; @@ -905,7 +913,8 @@ static void connect(struct backend_info *be) xen_blkbk_barrier(xbt, be, be->blkif->vbd.flush_support); - err = xenbus_printf(xbt, dev->nodename, "feature-persistent", "%u", 1); + err = xenbus_printf(xbt, dev->nodename, "feature-persistent", "%u", + be->blkif->vbd.feature_gnt_persistent); if (err) { xenbus_dev_fatal(dev, err, "writing %s/feature-persistent", dev->nodename); @@ -1066,7 +1075,6 @@ static int connect_ring(struct backend_info *be) { struct xenbus_device *dev = be->dev; struct xen_blkif *blkif = be->blkif; - unsigned int pers_grants; char protocol[64] = ""; int err, i; char *xspath; @@ -1092,9 +1100,11 @@ static int connect_ring(struct backend_info *be) xenbus_dev_fatal(dev, err, "unknown fe protocol %s", protocol); return -ENOSYS; } - pers_grants = xenbus_read_unsigned(dev->otherend, "feature-persistent", - 0); - blkif->vbd.feature_gnt_persistent = pers_grants; + if (blkif->vbd.feature_gnt_persistent) + blkif->vbd.feature_gnt_persistent = + xenbus_read_unsigned(dev->otherend, + "feature-persistent", 0); + blkif->vbd.overflow_max_grants = 0; /* @@ -1117,7 +1127,7 @@ static int connect_ring(struct backend_info *be) pr_info("%s: using %d queues, protocol %d (%s) %s\n", dev->nodename, blkif->nr_rings, blkif->blk_protocol, protocol, - pers_grants ? "persistent grants" : ""); + blkif->vbd.feature_gnt_persistent ? "persistent grants" : ""); ring_page_order = xenbus_read_unsigned(dev->otherend, "ring-page-order", 0); From 74a852479c68e4efb3865d5436fd69ec4f819f96 Mon Sep 17 00:00:00 2001 From: SeongJae Park Date: Wed, 23 Sep 2020 08:18:40 +0200 Subject: [PATCH 2/8] xen-blkfront: add a parameter for disabling of persistent grants MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Persistent grants feature provides high scalability. On some small systems, however, it could incur data copy overheads[1] and thus it is required to be disabled. It can be disabled from blkback side using a module parameter, 'feature_persistent'. But, it is impossible from blkfront side. For the reason, this commit adds a blkfront module parameter for disabling of the feature. [1] https://wiki.xen.org/wiki/Xen_4.3_Block_Protocol_Scalability Signed-off-by: SeongJae Park Reviewed-by: Juergen Gross Acked-by: Roger Pau Monné Link: https://lore.kernel.org/r/20200923061841.20531-3-sjpark@amazon.com Signed-off-by: Boris Ostrovsky --- .../ABI/testing/sysfs-driver-xen-blkfront | 9 +++++++++ drivers/block/xen-blkfront.c | 20 ++++++++++++++----- 2 files changed, 24 insertions(+), 5 deletions(-) diff --git a/Documentation/ABI/testing/sysfs-driver-xen-blkfront b/Documentation/ABI/testing/sysfs-driver-xen-blkfront index c0a6cb7eb314..9c31334cb2e6 100644 --- a/Documentation/ABI/testing/sysfs-driver-xen-blkfront +++ b/Documentation/ABI/testing/sysfs-driver-xen-blkfront @@ -8,3 +8,12 @@ Description: is 32 - higher value means more potential throughput but more memory usage. The backend picks the minimum of the frontend and its default backend value. + +What: /sys/module/xen_blkfront/parameters/feature_persistent +Date: September 2020 +KernelVersion: 5.10 +Contact: SeongJae Park +Description: + Whether to enable the persistent grants feature or not. Note + that this option only takes effect on newly created frontends. + The default is Y (enable). diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c index 91de2e0755ae..48629d3433b4 100644 --- a/drivers/block/xen-blkfront.c +++ b/drivers/block/xen-blkfront.c @@ -1866,8 +1866,8 @@ static int talk_to_blkback(struct xenbus_device *dev, message = "writing protocol"; goto abort_transaction; } - err = xenbus_printf(xbt, dev->nodename, - "feature-persistent", "%u", 1); + err = xenbus_printf(xbt, dev->nodename, "feature-persistent", "%u", + info->feature_persistent); if (err) dev_warn(&dev->dev, "writing persistent grants feature to xenbus"); @@ -1941,6 +1941,13 @@ static int negotiate_mq(struct blkfront_info *info) } return 0; } + +/* Enable the persistent grants feature. */ +static bool feature_persistent = true; +module_param(feature_persistent, bool, 0644); +MODULE_PARM_DESC(feature_persistent, + "Enables the persistent grants feature"); + /** * Entry point to this code when a new device is created. Allocate the basic * structures and the ring buffer for communication with the backend, and @@ -2007,6 +2014,8 @@ static int blkfront_probe(struct xenbus_device *dev, info->vdevice = vdevice; info->connected = BLKIF_STATE_DISCONNECTED; + info->feature_persistent = feature_persistent; + /* Front end dir is a number, which is used as the id. */ info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0); dev_set_drvdata(&dev->dev, info); @@ -2316,9 +2325,10 @@ static void blkfront_gather_backend_features(struct blkfront_info *info) if (xenbus_read_unsigned(info->xbdev->otherend, "feature-discard", 0)) blkfront_setup_discard(info); - info->feature_persistent = - !!xenbus_read_unsigned(info->xbdev->otherend, - "feature-persistent", 0); + if (info->feature_persistent) + info->feature_persistent = + !!xenbus_read_unsigned(info->xbdev->otherend, + "feature-persistent", 0); indirect_segments = xenbus_read_unsigned(info->xbdev->otherend, "feature-max-indirect-segments", 0); From 4553350ffe53c29156c61df584425ccfaabb2980 Mon Sep 17 00:00:00 2001 From: SeongJae Park Date: Wed, 23 Sep 2020 08:18:41 +0200 Subject: [PATCH 3/8] xen-blkfront: Apply changed parameter name to the document MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Commit 14e710fe7897 ("xen-blkfront: rename indirect descriptor parameter") changed the name of the module parameter for the maximum amount of segments in indirect requests but missed updating the document. This commit updates the document. Signed-off-by: SeongJae Park Reviewed-by: Juergen Gross Acked-by: Roger Pau Monné Link: https://lore.kernel.org/r/20200923061841.20531-4-sjpark@amazon.com Signed-off-by: Boris Ostrovsky --- Documentation/ABI/testing/sysfs-driver-xen-blkfront | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/Documentation/ABI/testing/sysfs-driver-xen-blkfront b/Documentation/ABI/testing/sysfs-driver-xen-blkfront index 9c31334cb2e6..28008905615f 100644 --- a/Documentation/ABI/testing/sysfs-driver-xen-blkfront +++ b/Documentation/ABI/testing/sysfs-driver-xen-blkfront @@ -1,4 +1,4 @@ -What: /sys/module/xen_blkfront/parameters/max +What: /sys/module/xen_blkfront/parameters/max_indirect_segments Date: June 2013 KernelVersion: 3.11 Contact: Konrad Rzeszutek Wilk From 5894048775df4a65ee2b58a7c2fa3ca8c6984a78 Mon Sep 17 00:00:00 2001 From: Juergen Gross Date: Thu, 22 Oct 2020 11:49:03 +0200 Subject: [PATCH 4/8] xen: remove no longer used functions With the switch to the lateeoi model for interdomain event channels some functions are no longer in use. Remove them. Suggested-by: Jan Beulich Signed-off-by: Juergen Gross Reviewed-by: Jan Beulich Link: https://lore.kernel.org/r/20201022094907.28560-2-jgross@suse.com Signed-off-by: Boris Ostrovsky --- drivers/xen/events/events_base.c | 21 --------------------- include/xen/events.h | 8 -------- 2 files changed, 29 deletions(-) diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c index cc317739e786..436682db41c5 100644 --- a/drivers/xen/events/events_base.c +++ b/drivers/xen/events/events_base.c @@ -1145,14 +1145,6 @@ static int bind_interdomain_evtchn_to_irq_chip(unsigned int remote_domain, chip); } -int bind_interdomain_evtchn_to_irq(unsigned int remote_domain, - evtchn_port_t remote_port) -{ - return bind_interdomain_evtchn_to_irq_chip(remote_domain, remote_port, - &xen_dynamic_chip); -} -EXPORT_SYMBOL_GPL(bind_interdomain_evtchn_to_irq); - int bind_interdomain_evtchn_to_irq_lateeoi(unsigned int remote_domain, evtchn_port_t remote_port) { @@ -1320,19 +1312,6 @@ static int bind_interdomain_evtchn_to_irqhandler_chip( return irq; } -int bind_interdomain_evtchn_to_irqhandler(unsigned int remote_domain, - evtchn_port_t remote_port, - irq_handler_t handler, - unsigned long irqflags, - const char *devname, - void *dev_id) -{ - return bind_interdomain_evtchn_to_irqhandler_chip(remote_domain, - remote_port, handler, irqflags, devname, - dev_id, &xen_dynamic_chip); -} -EXPORT_SYMBOL_GPL(bind_interdomain_evtchn_to_irqhandler); - int bind_interdomain_evtchn_to_irqhandler_lateeoi(unsigned int remote_domain, evtchn_port_t remote_port, irq_handler_t handler, diff --git a/include/xen/events.h b/include/xen/events.h index 3b8155c2ea03..8ec418e30c7f 100644 --- a/include/xen/events.h +++ b/include/xen/events.h @@ -35,16 +35,8 @@ int bind_ipi_to_irqhandler(enum ipi_vector ipi, unsigned long irqflags, const char *devname, void *dev_id); -int bind_interdomain_evtchn_to_irq(unsigned int remote_domain, - evtchn_port_t remote_port); int bind_interdomain_evtchn_to_irq_lateeoi(unsigned int remote_domain, evtchn_port_t remote_port); -int bind_interdomain_evtchn_to_irqhandler(unsigned int remote_domain, - evtchn_port_t remote_port, - irq_handler_t handler, - unsigned long irqflags, - const char *devname, - void *dev_id); int bind_interdomain_evtchn_to_irqhandler_lateeoi(unsigned int remote_domain, evtchn_port_t remote_port, irq_handler_t handler, From 7e14cde10b1ea8157cca7b6b56901ef9cd4d36a3 Mon Sep 17 00:00:00 2001 From: Juergen Gross Date: Thu, 22 Oct 2020 11:49:04 +0200 Subject: [PATCH 5/8] xen/events: make struct irq_info private to events_base.c The struct irq_info of Xen's event handling is used only for two evtchn_ops functions outside of events_base.c. Those two functions can easily be switched to avoid that usage. This allows to make struct irq_info and its related access functions private to events_base.c. Signed-off-by: Juergen Gross Reviewed-by: Jan Beulich Link: https://lore.kernel.org/r/20201022094907.28560-3-jgross@suse.com Signed-off-by: Boris Ostrovsky --- drivers/xen/events/events_2l.c | 7 +-- drivers/xen/events/events_base.c | 63 ++++++++++++++++++++++--- drivers/xen/events/events_fifo.c | 6 +-- drivers/xen/events/events_internal.h | 70 ++++------------------------ 4 files changed, 73 insertions(+), 73 deletions(-) diff --git a/drivers/xen/events/events_2l.c b/drivers/xen/events/events_2l.c index fe5ad0e89cd8..da87f3a1e351 100644 --- a/drivers/xen/events/events_2l.c +++ b/drivers/xen/events/events_2l.c @@ -47,10 +47,11 @@ static unsigned evtchn_2l_max_channels(void) return EVTCHN_2L_NR_CHANNELS; } -static void evtchn_2l_bind_to_cpu(struct irq_info *info, unsigned cpu) +static void evtchn_2l_bind_to_cpu(evtchn_port_t evtchn, unsigned int cpu, + unsigned int old_cpu) { - clear_bit(info->evtchn, BM(per_cpu(cpu_evtchn_mask, info->cpu))); - set_bit(info->evtchn, BM(per_cpu(cpu_evtchn_mask, cpu))); + clear_bit(evtchn, BM(per_cpu(cpu_evtchn_mask, old_cpu))); + set_bit(evtchn, BM(per_cpu(cpu_evtchn_mask, cpu))); } static void evtchn_2l_clear_pending(evtchn_port_t port) diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c index 436682db41c5..1c25580c7691 100644 --- a/drivers/xen/events/events_base.c +++ b/drivers/xen/events/events_base.c @@ -70,6 +70,57 @@ #undef MODULE_PARAM_PREFIX #define MODULE_PARAM_PREFIX "xen." +/* Interrupt types. */ +enum xen_irq_type { + IRQT_UNBOUND = 0, + IRQT_PIRQ, + IRQT_VIRQ, + IRQT_IPI, + IRQT_EVTCHN +}; + +/* + * Packed IRQ information: + * type - enum xen_irq_type + * event channel - irq->event channel mapping + * cpu - cpu this event channel is bound to + * index - type-specific information: + * PIRQ - vector, with MSB being "needs EIO", or physical IRQ of the HVM + * guest, or GSI (real passthrough IRQ) of the device. + * VIRQ - virq number + * IPI - IPI vector + * EVTCHN - + */ +struct irq_info { + struct list_head list; + struct list_head eoi_list; + short refcnt; + short spurious_cnt; + enum xen_irq_type type; /* type */ + unsigned irq; + evtchn_port_t evtchn; /* event channel */ + unsigned short cpu; /* cpu bound */ + unsigned short eoi_cpu; /* EOI must happen on this cpu-1 */ + unsigned int irq_epoch; /* If eoi_cpu valid: irq_epoch of event */ + u64 eoi_time; /* Time in jiffies when to EOI. */ + + union { + unsigned short virq; + enum ipi_vector ipi; + struct { + unsigned short pirq; + unsigned short gsi; + unsigned char vector; + unsigned char flags; + uint16_t domid; + } pirq; + } u; +}; + +#define PIRQ_NEEDS_EOI (1 << 0) +#define PIRQ_SHAREABLE (1 << 1) +#define PIRQ_MSI_GROUP (1 << 2) + static uint __read_mostly event_loop_timeout = 2; module_param(event_loop_timeout, uint, 0644); @@ -110,7 +161,7 @@ static DEFINE_PER_CPU(int [NR_VIRQS], virq_to_irq) = {[0 ... NR_VIRQS-1] = -1}; /* IRQ <-> IPI mapping */ static DEFINE_PER_CPU(int [XEN_NR_IPIS], ipi_to_irq) = {[0 ... XEN_NR_IPIS-1] = -1}; -int **evtchn_to_irq; +static int **evtchn_to_irq; #ifdef CONFIG_X86 static unsigned long *pirq_eoi_map; #endif @@ -190,7 +241,7 @@ int get_evtchn_to_irq(evtchn_port_t evtchn) } /* Get info for IRQ */ -struct irq_info *info_for_irq(unsigned irq) +static struct irq_info *info_for_irq(unsigned irq) { if (irq < nr_legacy_irqs()) return legacy_info_ptrs[irq]; @@ -228,7 +279,7 @@ static int xen_irq_info_common_setup(struct irq_info *info, irq_clear_status_flags(irq, IRQ_NOREQUEST|IRQ_NOAUTOEN); - return xen_evtchn_port_setup(info); + return xen_evtchn_port_setup(evtchn); } static int xen_irq_info_evtchn_setup(unsigned irq, @@ -351,7 +402,7 @@ static enum xen_irq_type type_from_irq(unsigned irq) return info_for_irq(irq)->type; } -unsigned cpu_from_irq(unsigned irq) +static unsigned cpu_from_irq(unsigned irq) { return info_for_irq(irq)->cpu; } @@ -391,7 +442,7 @@ static void bind_evtchn_to_cpu(evtchn_port_t evtchn, unsigned int cpu) #ifdef CONFIG_SMP cpumask_copy(irq_get_affinity_mask(irq), cpumask_of(cpu)); #endif - xen_evtchn_port_bind_to_cpu(info, cpu); + xen_evtchn_port_bind_to_cpu(evtchn, cpu, info->cpu); info->cpu = cpu; } @@ -745,7 +796,7 @@ static unsigned int __startup_pirq(unsigned int irq) info->evtchn = evtchn; bind_evtchn_to_cpu(evtchn, 0); - rc = xen_evtchn_port_setup(info); + rc = xen_evtchn_port_setup(evtchn); if (rc) goto err; diff --git a/drivers/xen/events/events_fifo.c b/drivers/xen/events/events_fifo.c index 6085a808da95..243e7b6d7b96 100644 --- a/drivers/xen/events/events_fifo.c +++ b/drivers/xen/events/events_fifo.c @@ -138,9 +138,8 @@ static void init_array_page(event_word_t *array_page) array_page[i] = 1 << EVTCHN_FIFO_MASKED; } -static int evtchn_fifo_setup(struct irq_info *info) +static int evtchn_fifo_setup(evtchn_port_t port) { - evtchn_port_t port = info->evtchn; unsigned new_array_pages; int ret; @@ -186,7 +185,8 @@ static int evtchn_fifo_setup(struct irq_info *info) return ret; } -static void evtchn_fifo_bind_to_cpu(struct irq_info *info, unsigned cpu) +static void evtchn_fifo_bind_to_cpu(evtchn_port_t evtchn, unsigned int cpu, + unsigned int old_cpu) { /* no-op */ } diff --git a/drivers/xen/events/events_internal.h b/drivers/xen/events/events_internal.h index 82937d90d7d7..0a97c0549db7 100644 --- a/drivers/xen/events/events_internal.h +++ b/drivers/xen/events/events_internal.h @@ -7,65 +7,15 @@ #ifndef __EVENTS_INTERNAL_H__ #define __EVENTS_INTERNAL_H__ -/* Interrupt types. */ -enum xen_irq_type { - IRQT_UNBOUND = 0, - IRQT_PIRQ, - IRQT_VIRQ, - IRQT_IPI, - IRQT_EVTCHN -}; - -/* - * Packed IRQ information: - * type - enum xen_irq_type - * event channel - irq->event channel mapping - * cpu - cpu this event channel is bound to - * index - type-specific information: - * PIRQ - vector, with MSB being "needs EIO", or physical IRQ of the HVM - * guest, or GSI (real passthrough IRQ) of the device. - * VIRQ - virq number - * IPI - IPI vector - * EVTCHN - - */ -struct irq_info { - struct list_head list; - struct list_head eoi_list; - short refcnt; - short spurious_cnt; - enum xen_irq_type type; /* type */ - unsigned irq; - evtchn_port_t evtchn; /* event channel */ - unsigned short cpu; /* cpu bound */ - unsigned short eoi_cpu; /* EOI must happen on this cpu */ - unsigned int irq_epoch; /* If eoi_cpu valid: irq_epoch of event */ - u64 eoi_time; /* Time in jiffies when to EOI. */ - - union { - unsigned short virq; - enum ipi_vector ipi; - struct { - unsigned short pirq; - unsigned short gsi; - unsigned char vector; - unsigned char flags; - uint16_t domid; - } pirq; - } u; -}; - -#define PIRQ_NEEDS_EOI (1 << 0) -#define PIRQ_SHAREABLE (1 << 1) -#define PIRQ_MSI_GROUP (1 << 2) - struct evtchn_loop_ctrl; struct evtchn_ops { unsigned (*max_channels)(void); unsigned (*nr_channels)(void); - int (*setup)(struct irq_info *info); - void (*bind_to_cpu)(struct irq_info *info, unsigned cpu); + int (*setup)(evtchn_port_t port); + void (*bind_to_cpu)(evtchn_port_t evtchn, unsigned int cpu, + unsigned int old_cpu); void (*clear_pending)(evtchn_port_t port); void (*set_pending)(evtchn_port_t port); @@ -83,12 +33,9 @@ struct evtchn_ops { extern const struct evtchn_ops *evtchn_ops; -extern int **evtchn_to_irq; int get_evtchn_to_irq(evtchn_port_t evtchn); void handle_irq_for_port(evtchn_port_t port, struct evtchn_loop_ctrl *ctrl); -struct irq_info *info_for_irq(unsigned irq); -unsigned cpu_from_irq(unsigned irq); unsigned int cpu_from_evtchn(evtchn_port_t evtchn); static inline unsigned xen_evtchn_max_channels(void) @@ -100,17 +47,18 @@ static inline unsigned xen_evtchn_max_channels(void) * Do any ABI specific setup for a bound event channel before it can * be unmasked and used. */ -static inline int xen_evtchn_port_setup(struct irq_info *info) +static inline int xen_evtchn_port_setup(evtchn_port_t evtchn) { if (evtchn_ops->setup) - return evtchn_ops->setup(info); + return evtchn_ops->setup(evtchn); return 0; } -static inline void xen_evtchn_port_bind_to_cpu(struct irq_info *info, - unsigned cpu) +static inline void xen_evtchn_port_bind_to_cpu(evtchn_port_t evtchn, + unsigned int cpu, + unsigned int old_cpu) { - evtchn_ops->bind_to_cpu(info, cpu); + evtchn_ops->bind_to_cpu(evtchn, cpu, old_cpu); } static inline void clear_evtchn(evtchn_port_t port) From d04b1ae5a9b0c868dda8b4b34175ef08f3cb9e93 Mon Sep 17 00:00:00 2001 From: Juergen Gross Date: Thu, 22 Oct 2020 11:49:05 +0200 Subject: [PATCH 6/8] xen/events: only register debug interrupt for 2-level events xen_debug_interrupt() is specific to 2-level event handling. So don't register it with fifo event handling being active. Signed-off-by: Juergen Gross Reviewed-by: Jan Beulich Link: https://lore.kernel.org/r/20201022094907.28560-4-jgross@suse.com Signed-off-by: Boris Ostrovsky --- arch/x86/xen/smp.c | 19 +++++++++++-------- arch/x86/xen/xen-ops.h | 2 ++ drivers/xen/events/events_base.c | 10 ++++++---- 3 files changed, 19 insertions(+), 12 deletions(-) diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c index 2097fa0ebdb5..c1b2f764b29a 100644 --- a/arch/x86/xen/smp.c +++ b/arch/x86/xen/smp.c @@ -88,14 +88,17 @@ int xen_smp_intr_init(unsigned int cpu) per_cpu(xen_callfunc_irq, cpu).irq = rc; per_cpu(xen_callfunc_irq, cpu).name = callfunc_name; - debug_name = kasprintf(GFP_KERNEL, "debug%d", cpu); - rc = bind_virq_to_irqhandler(VIRQ_DEBUG, cpu, xen_debug_interrupt, - IRQF_PERCPU | IRQF_NOBALANCING, - debug_name, NULL); - if (rc < 0) - goto fail; - per_cpu(xen_debug_irq, cpu).irq = rc; - per_cpu(xen_debug_irq, cpu).name = debug_name; + if (!xen_fifo_events) { + debug_name = kasprintf(GFP_KERNEL, "debug%d", cpu); + rc = bind_virq_to_irqhandler(VIRQ_DEBUG, cpu, + xen_debug_interrupt, + IRQF_PERCPU | IRQF_NOBALANCING, + debug_name, NULL); + if (rc < 0) + goto fail; + per_cpu(xen_debug_irq, cpu).irq = rc; + per_cpu(xen_debug_irq, cpu).name = debug_name; + } callfunc_name = kasprintf(GFP_KERNEL, "callfuncsingle%d", cpu); rc = bind_ipi_to_irqhandler(XEN_CALL_FUNCTION_SINGLE_VECTOR, diff --git a/arch/x86/xen/xen-ops.h b/arch/x86/xen/xen-ops.h index 45d556f71858..9546c3384c75 100644 --- a/arch/x86/xen/xen-ops.h +++ b/arch/x86/xen/xen-ops.h @@ -29,6 +29,8 @@ extern struct start_info *xen_start_info; extern struct shared_info xen_dummy_shared_info; extern struct shared_info *HYPERVISOR_shared_info; +extern bool xen_fifo_events; + void xen_setup_mfn_list_list(void); void xen_build_mfn_list_list(void); void xen_setup_machphys_mapping(void); diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c index 1c25580c7691..6038c4c35db5 100644 --- a/drivers/xen/events/events_base.c +++ b/drivers/xen/events/events_base.c @@ -2050,8 +2050,8 @@ void xen_setup_callback_vector(void) {} static inline void xen_alloc_callback_vector(void) {} #endif -static bool fifo_events = true; -module_param(fifo_events, bool, 0); +bool xen_fifo_events = true; +module_param_named(fifo_events, xen_fifo_events, bool, 0); static int xen_evtchn_cpu_prepare(unsigned int cpu) { @@ -2080,10 +2080,12 @@ void __init xen_init_IRQ(void) int ret = -EINVAL; evtchn_port_t evtchn; - if (fifo_events) + if (xen_fifo_events) ret = xen_evtchn_fifo_init(); - if (ret < 0) + if (ret < 0) { xen_evtchn_2l_init(); + xen_fifo_events = false; + } xen_cpu_init_eoi(smp_processor_id()); From eabe741782d5a52ce884dba4bab8825f977ab1eb Mon Sep 17 00:00:00 2001 From: Juergen Gross Date: Thu, 22 Oct 2020 11:49:06 +0200 Subject: [PATCH 7/8] xen/events: unmask a fifo event channel only if it was masked Unmasking an event channel with fifo events channels being used can require a hypercall to be made, so try to avoid that by checking whether the event channel was really masked. Suggested-by: Jan Beulich Signed-off-by: Juergen Gross Reviewed-by: Jan Beulich Link: https://lore.kernel.org/r/20201022094907.28560-5-jgross@suse.com Signed-off-by: Boris Ostrovsky --- drivers/xen/events/events_fifo.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/xen/events/events_fifo.c b/drivers/xen/events/events_fifo.c index 243e7b6d7b96..b234f1766810 100644 --- a/drivers/xen/events/events_fifo.c +++ b/drivers/xen/events/events_fifo.c @@ -237,6 +237,9 @@ static bool clear_masked_cond(volatile event_word_t *word) w = *word; do { + if (!(w & (1 << EVTCHN_FIFO_MASKED))) + return true; + if (w & (1 << EVTCHN_FIFO_PENDING)) return false; From 1a89c1dc9520b908e7894652ee2b19db9de37b64 Mon Sep 17 00:00:00 2001 From: Juergen Gross Date: Thu, 22 Oct 2020 11:49:07 +0200 Subject: [PATCH 8/8] Documentation: add xen.fifo_events kernel parameter description The kernel boot parameter xen.fifo_events isn't listed in Documentation/admin-guide/kernel-parameters.txt. Add it. Signed-off-by: Juergen Gross Reviewed-by: Jan Beulich Link: https://lore.kernel.org/r/20201022094907.28560-6-jgross@suse.com Signed-off-by: Boris Ostrovsky --- Documentation/admin-guide/kernel-parameters.txt | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 89d977f0b786..935f890cfdad 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -5836,6 +5836,13 @@ After which time (jiffies) the event handling loop should start to delay EOI handling. Default is 2. + xen.fifo_events= [XEN] + Boolean parameter to disable using fifo event handling + even if available. Normally fifo event handling is + preferred over the 2-level event handling, as it is + fairer and the number of possible event channels is + much higher. Default is on (use fifo events). + nopv= [X86,XEN,KVM,HYPER_V,VMWARE] Disables the PV optimizations forcing the guest to run as generic guest with no PV drivers. Currently support