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authorLinus Torvalds <torvalds@linux-foundation.org>2020-06-03 15:00:05 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-06-03 15:00:05 -0700
commit6b2591c21273ebf65c13dae5d260ce88f0f197dd (patch)
tree9d19b72d7d9461c210b8f38e57720268bf85c96f /drivers/hv/vmbus_drv.c
parentf1e455352b6f503532eb3637d0a6d991895e7856 (diff)
parentafaa33da08abd10be8978781d7c99a9e67d2bbff (diff)
Merge tag 'hyperv-next-signed' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux
Pull hyper-v updates from Wei Liu: - a series from Andrea to support channel reassignment - a series from Vitaly to clean up Vmbus message handling - a series from Michael to clean up and augment hyperv-tlfs.h - patches from Andy to clean up GUID usage in Hyper-V code - a few other misc patches * tag 'hyperv-next-signed' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux: (29 commits) Drivers: hv: vmbus: Resolve more races involving init_vp_index() Drivers: hv: vmbus: Resolve race between init_vp_index() and CPU hotplug vmbus: Replace zero-length array with flexible-array Driver: hv: vmbus: drop a no long applicable comment hyper-v: Switch to use UUID types directly hyper-v: Replace open-coded variant of %*phN specifier hyper-v: Supply GUID pointer to printf() like functions hyper-v: Use UUID API for exporting the GUID (part 2) asm-generic/hyperv: Add definitions for Get/SetVpRegister hypercalls x86/hyperv: Split hyperv-tlfs.h into arch dependent and independent files x86/hyperv: Remove HV_PROCESSOR_POWER_STATE #defines KVM: x86: hyperv: Remove duplicate definitions of Reference TSC Page drivers: hv: remove redundant assignment to pointer primary_channel scsi: storvsc: Re-init stor_chns when a channel interrupt is re-assigned Drivers: hv: vmbus: Introduce the CHANNELMSG_MODIFYCHANNEL message type Drivers: hv: vmbus: Synchronize init_vp_index() vs. CPU hotplug Drivers: hv: vmbus: Remove the unused HV_LOCALIZED channel affinity logic PCI: hv: Prepare hv_compose_msi_msg() for the VMBus-channel-interrupt-to-vCPU reassignment functionality Drivers: hv: vmbus: Use a spin lock for synchronizing channel scheduling vs. channel removal hv_utils: Always execute the fcopy and vss callbacks in a tasklet ...
Diffstat (limited to 'drivers/hv/vmbus_drv.c')
-rw-r--r--drivers/hv/vmbus_drv.c314
1 files changed, 243 insertions, 71 deletions
diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index e06c6b9555cf..9147ee9d5f7d 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -117,14 +117,6 @@ static int vmbus_exists(void)
return 0;
}
-#define VMBUS_ALIAS_LEN ((sizeof((struct hv_vmbus_device_id *)0)->guid) * 2)
-static void print_alias_name(struct hv_device *hv_dev, char *alias_name)
-{
- int i;
- for (i = 0; i < VMBUS_ALIAS_LEN; i += 2)
- sprintf(&alias_name[i], "%02x", hv_dev->dev_type.b[i/2]);
-}
-
static u8 channel_monitor_group(const struct vmbus_channel *channel)
{
return (u8)channel->offermsg.monitorid / 32;
@@ -201,7 +193,7 @@ static ssize_t class_id_show(struct device *dev,
if (!hv_dev->channel)
return -ENODEV;
return sprintf(buf, "{%pUl}\n",
- hv_dev->channel->offermsg.offer.if_type.b);
+ &hv_dev->channel->offermsg.offer.if_type);
}
static DEVICE_ATTR_RO(class_id);
@@ -213,7 +205,7 @@ static ssize_t device_id_show(struct device *dev,
if (!hv_dev->channel)
return -ENODEV;
return sprintf(buf, "{%pUl}\n",
- hv_dev->channel->offermsg.offer.if_instance.b);
+ &hv_dev->channel->offermsg.offer.if_instance);
}
static DEVICE_ATTR_RO(device_id);
@@ -221,10 +213,8 @@ static ssize_t modalias_show(struct device *dev,
struct device_attribute *dev_attr, char *buf)
{
struct hv_device *hv_dev = device_to_hv_device(dev);
- char alias_name[VMBUS_ALIAS_LEN + 1];
- print_alias_name(hv_dev, alias_name);
- return sprintf(buf, "vmbus:%s\n", alias_name);
+ return sprintf(buf, "vmbus:%*phN\n", UUID_SIZE, &hv_dev->dev_type);
}
static DEVICE_ATTR_RO(modalias);
@@ -693,12 +683,9 @@ __ATTRIBUTE_GROUPS(vmbus_dev);
static int vmbus_uevent(struct device *device, struct kobj_uevent_env *env)
{
struct hv_device *dev = device_to_hv_device(device);
- int ret;
- char alias_name[VMBUS_ALIAS_LEN + 1];
+ const char *format = "MODALIAS=vmbus:%*phN";
- print_alias_name(dev, alias_name);
- ret = add_uevent_var(env, "MODALIAS=vmbus:%s", alias_name);
- return ret;
+ return add_uevent_var(env, format, UUID_SIZE, &dev->dev_type);
}
static const struct hv_vmbus_device_id *
@@ -1033,7 +1020,10 @@ static struct bus_type hv_bus = {
struct onmessage_work_context {
struct work_struct work;
- struct hv_message msg;
+ struct {
+ struct hv_message_header header;
+ u8 payload[];
+ } msg;
};
static void vmbus_onmessage_work(struct work_struct *work)
@@ -1046,7 +1036,8 @@ static void vmbus_onmessage_work(struct work_struct *work)
ctx = container_of(work, struct onmessage_work_context,
work);
- vmbus_onmessage(&ctx->msg);
+ vmbus_onmessage((struct vmbus_channel_message_header *)
+ &ctx->msg.payload);
kfree(ctx);
}
@@ -1061,6 +1052,13 @@ void vmbus_on_msg_dpc(unsigned long data)
struct onmessage_work_context *ctx;
u32 message_type = msg->header.message_type;
+ /*
+ * 'enum vmbus_channel_message_type' is supposed to always be 'u32' as
+ * it is being used in 'struct vmbus_channel_message_header' definition
+ * which is supposed to match hypervisor ABI.
+ */
+ BUILD_BUG_ON(sizeof(enum vmbus_channel_message_type) != sizeof(u32));
+
if (message_type == HVMSG_NONE)
/* no msg */
return;
@@ -1074,41 +1072,88 @@ void vmbus_on_msg_dpc(unsigned long data)
goto msg_handled;
}
+ if (msg->header.payload_size > HV_MESSAGE_PAYLOAD_BYTE_COUNT) {
+ WARN_ONCE(1, "payload size is too large (%d)\n",
+ msg->header.payload_size);
+ goto msg_handled;
+ }
+
entry = &channel_message_table[hdr->msgtype];
if (!entry->message_handler)
goto msg_handled;
+ if (msg->header.payload_size < entry->min_payload_len) {
+ WARN_ONCE(1, "message too short: msgtype=%d len=%d\n",
+ hdr->msgtype, msg->header.payload_size);
+ goto msg_handled;
+ }
+
if (entry->handler_type == VMHT_BLOCKING) {
- ctx = kmalloc(sizeof(*ctx), GFP_ATOMIC);
+ ctx = kmalloc(sizeof(*ctx) + msg->header.payload_size,
+ GFP_ATOMIC);
if (ctx == NULL)
return;
INIT_WORK(&ctx->work, vmbus_onmessage_work);
- memcpy(&ctx->msg, msg, sizeof(*msg));
+ memcpy(&ctx->msg, msg, sizeof(msg->header) +
+ msg->header.payload_size);
/*
* The host can generate a rescind message while we
* may still be handling the original offer. We deal with
- * this condition by ensuring the processing is done on the
- * same CPU.
+ * this condition by relying on the synchronization provided
+ * by offer_in_progress and by channel_mutex. See also the
+ * inline comments in vmbus_onoffer_rescind().
*/
switch (hdr->msgtype) {
case CHANNELMSG_RESCIND_CHANNELOFFER:
/*
* If we are handling the rescind message;
* schedule the work on the global work queue.
+ *
+ * The OFFER message and the RESCIND message should
+ * not be handled by the same serialized work queue,
+ * because the OFFER handler may call vmbus_open(),
+ * which tries to open the channel by sending an
+ * OPEN_CHANNEL message to the host and waits for
+ * the host's response; however, if the host has
+ * rescinded the channel before it receives the
+ * OPEN_CHANNEL message, the host just silently
+ * ignores the OPEN_CHANNEL message; as a result,
+ * the guest's OFFER handler hangs for ever, if we
+ * handle the RESCIND message in the same serialized
+ * work queue: the RESCIND handler can not start to
+ * run before the OFFER handler finishes.
*/
- schedule_work_on(vmbus_connection.connect_cpu,
- &ctx->work);
+ schedule_work(&ctx->work);
break;
case CHANNELMSG_OFFERCHANNEL:
+ /*
+ * The host sends the offer message of a given channel
+ * before sending the rescind message of the same
+ * channel. These messages are sent to the guest's
+ * connect CPU; the guest then starts processing them
+ * in the tasklet handler on this CPU:
+ *
+ * VMBUS_CONNECT_CPU
+ *
+ * [vmbus_on_msg_dpc()]
+ * atomic_inc() // CHANNELMSG_OFFERCHANNEL
+ * queue_work()
+ * ...
+ * [vmbus_on_msg_dpc()]
+ * schedule_work() // CHANNELMSG_RESCIND_CHANNELOFFER
+ *
+ * We rely on the memory-ordering properties of the
+ * queue_work() and schedule_work() primitives, which
+ * guarantee that the atomic increment will be visible
+ * to the CPUs which will execute the offer & rescind
+ * works by the time these works will start execution.
+ */
atomic_inc(&vmbus_connection.offer_in_progress);
- queue_work_on(vmbus_connection.connect_cpu,
- vmbus_connection.work_queue,
- &ctx->work);
- break;
+ fallthrough;
default:
queue_work(vmbus_connection.work_queue, &ctx->work);
@@ -1133,10 +1178,11 @@ static void vmbus_force_channel_rescinded(struct vmbus_channel *channel)
WARN_ON(!is_hvsock_channel(channel));
/*
- * sizeof(*ctx) is small and the allocation should really not fail,
+ * Allocation size is small and the allocation should really not fail,
* otherwise the state of the hv_sock connections ends up in limbo.
*/
- ctx = kzalloc(sizeof(*ctx), GFP_KERNEL | __GFP_NOFAIL);
+ ctx = kzalloc(sizeof(*ctx) + sizeof(*rescind),
+ GFP_KERNEL | __GFP_NOFAIL);
/*
* So far, these are not really used by Linux. Just set them to the
@@ -1146,31 +1192,17 @@ static void vmbus_force_channel_rescinded(struct vmbus_channel *channel)
ctx->msg.header.payload_size = sizeof(*rescind);
/* These values are actually used by Linux. */
- rescind = (struct vmbus_channel_rescind_offer *)ctx->msg.u.payload;
+ rescind = (struct vmbus_channel_rescind_offer *)ctx->msg.payload;
rescind->header.msgtype = CHANNELMSG_RESCIND_CHANNELOFFER;
rescind->child_relid = channel->offermsg.child_relid;
INIT_WORK(&ctx->work, vmbus_onmessage_work);
- queue_work_on(vmbus_connection.connect_cpu,
- vmbus_connection.work_queue,
- &ctx->work);
+ queue_work(vmbus_connection.work_queue, &ctx->work);
}
#endif /* CONFIG_PM_SLEEP */
/*
- * Direct callback for channels using other deferred processing
- */
-static void vmbus_channel_isr(struct vmbus_channel *channel)
-{
- void (*callback_fn)(void *);
-
- callback_fn = READ_ONCE(channel->onchannel_callback);
- if (likely(callback_fn != NULL))
- (*callback_fn)(channel->channel_callback_context);
-}
-
-/*
* Schedule all channels with events pending
*/
static void vmbus_chan_sched(struct hv_per_cpu_context *hv_cpu)
@@ -1200,6 +1232,7 @@ static void vmbus_chan_sched(struct hv_per_cpu_context *hv_cpu)
return;
for_each_set_bit(relid, recv_int_page, maxbits) {
+ void (*callback_fn)(void *context);
struct vmbus_channel *channel;
if (!sync_test_and_clear_bit(relid, recv_int_page))
@@ -1209,33 +1242,54 @@ static void vmbus_chan_sched(struct hv_per_cpu_context *hv_cpu)
if (relid == 0)
continue;
+ /*
+ * Pairs with the kfree_rcu() in vmbus_chan_release().
+ * Guarantees that the channel data structure doesn't
+ * get freed while the channel pointer below is being
+ * dereferenced.
+ */
rcu_read_lock();
/* Find channel based on relid */
- list_for_each_entry_rcu(channel, &hv_cpu->chan_list, percpu_list) {
- if (channel->offermsg.child_relid != relid)
- continue;
+ channel = relid2channel(relid);
+ if (channel == NULL)
+ goto sched_unlock_rcu;
- if (channel->rescind)
- continue;
+ if (channel->rescind)
+ goto sched_unlock_rcu;
- trace_vmbus_chan_sched(channel);
+ /*
+ * Make sure that the ring buffer data structure doesn't get
+ * freed while we dereference the ring buffer pointer. Test
+ * for the channel's onchannel_callback being NULL within a
+ * sched_lock critical section. See also the inline comments
+ * in vmbus_reset_channel_cb().
+ */
+ spin_lock(&channel->sched_lock);
- ++channel->interrupts;
+ callback_fn = channel->onchannel_callback;
+ if (unlikely(callback_fn == NULL))
+ goto sched_unlock;
- switch (channel->callback_mode) {
- case HV_CALL_ISR:
- vmbus_channel_isr(channel);
- break;
+ trace_vmbus_chan_sched(channel);
- case HV_CALL_BATCHED:
- hv_begin_read(&channel->inbound);
- /* fallthrough */
- case HV_CALL_DIRECT:
- tasklet_schedule(&channel->callback_event);
- }
+ ++channel->interrupts;
+
+ switch (channel->callback_mode) {
+ case HV_CALL_ISR:
+ (*callback_fn)(channel->channel_callback_context);
+ break;
+
+ case HV_CALL_BATCHED:
+ hv_begin_read(&channel->inbound);
+ fallthrough;
+ case HV_CALL_DIRECT:
+ tasklet_schedule(&channel->callback_event);
}
+sched_unlock:
+ spin_unlock(&channel->sched_lock);
+sched_unlock_rcu:
rcu_read_unlock();
}
}
@@ -1364,7 +1418,6 @@ static int vmbus_bus_init(void)
{
int ret;
- /* Hypervisor initialization...setup hypercall page..etc */
ret = hv_init();
if (ret != 0) {
pr_err("Unable to initialize the hypervisor - 0x%x\n", ret);
@@ -1553,8 +1606,24 @@ static ssize_t vmbus_chan_attr_show(struct kobject *kobj,
return attribute->show(chan, buf);
}
+static ssize_t vmbus_chan_attr_store(struct kobject *kobj,
+ struct attribute *attr, const char *buf,
+ size_t count)
+{
+ const struct vmbus_chan_attribute *attribute
+ = container_of(attr, struct vmbus_chan_attribute, attr);
+ struct vmbus_channel *chan
+ = container_of(kobj, struct vmbus_channel, kobj);
+
+ if (!attribute->store)
+ return -EIO;
+
+ return attribute->store(chan, buf, count);
+}
+
static const struct sysfs_ops vmbus_chan_sysfs_ops = {
.show = vmbus_chan_attr_show,
+ .store = vmbus_chan_attr_store,
};
static ssize_t out_mask_show(struct vmbus_channel *channel, char *buf)
@@ -1625,11 +1694,110 @@ static ssize_t write_avail_show(struct vmbus_channel *channel, char *buf)
}
static VMBUS_CHAN_ATTR_RO(write_avail);
-static ssize_t show_target_cpu(struct vmbus_channel *channel, char *buf)
+static ssize_t target_cpu_show(struct vmbus_channel *channel, char *buf)
{
return sprintf(buf, "%u\n", channel->target_cpu);
}
-static VMBUS_CHAN_ATTR(cpu, S_IRUGO, show_target_cpu, NULL);
+static ssize_t target_cpu_store(struct vmbus_channel *channel,
+ const char *buf, size_t count)
+{
+ u32 target_cpu, origin_cpu;
+ ssize_t ret = count;
+
+ if (vmbus_proto_version < VERSION_WIN10_V4_1)
+ return -EIO;
+
+ if (sscanf(buf, "%uu", &target_cpu) != 1)
+ return -EIO;
+
+ /* Validate target_cpu for the cpumask_test_cpu() operation below. */
+ if (target_cpu >= nr_cpumask_bits)
+ return -EINVAL;
+
+ /* No CPUs should come up or down during this. */
+ cpus_read_lock();
+
+ if (!cpumask_test_cpu(target_cpu, cpu_online_mask)) {
+ cpus_read_unlock();
+ return -EINVAL;
+ }
+
+ /*
+ * Synchronizes target_cpu_store() and channel closure:
+ *
+ * { Initially: state = CHANNEL_OPENED }
+ *
+ * CPU1 CPU2
+ *
+ * [target_cpu_store()] [vmbus_disconnect_ring()]
+ *
+ * LOCK channel_mutex LOCK channel_mutex
+ * LOAD r1 = state LOAD r2 = state
+ * IF (r1 == CHANNEL_OPENED) IF (r2 == CHANNEL_OPENED)
+ * SEND MODIFYCHANNEL STORE state = CHANNEL_OPEN
+ * [...] SEND CLOSECHANNEL
+ * UNLOCK channel_mutex UNLOCK channel_mutex
+ *
+ * Forbids: r1 == r2 == CHANNEL_OPENED (i.e., CPU1's LOCK precedes
+ * CPU2's LOCK) && CPU2's SEND precedes CPU1's SEND
+ *
+ * Note. The host processes the channel messages "sequentially", in
+ * the order in which they are received on a per-partition basis.
+ */
+ mutex_lock(&vmbus_connection.channel_mutex);
+
+ /*
+ * Hyper-V will ignore MODIFYCHANNEL messages for "non-open" channels;
+ * avoid sending the message and fail here for such channels.
+ */
+ if (channel->state != CHANNEL_OPENED_STATE) {
+ ret = -EIO;
+ goto cpu_store_unlock;
+ }
+
+ origin_cpu = channel->target_cpu;
+ if (target_cpu == origin_cpu)
+ goto cpu_store_unlock;
+
+ if (vmbus_send_modifychannel(channel->offermsg.child_relid,
+ hv_cpu_number_to_vp_number(target_cpu))) {
+ ret = -EIO;
+ goto cpu_store_unlock;
+ }
+
+ /*
+ * Warning. At this point, there is *no* guarantee that the host will
+ * have successfully processed the vmbus_send_modifychannel() request.
+ * See the header comment of vmbus_send_modifychannel() for more info.
+ *
+ * Lags in the processing of the above vmbus_send_modifychannel() can
+ * result in missed interrupts if the "old" target CPU is taken offline
+ * before Hyper-V starts sending interrupts to the "new" target CPU.
+ * But apart from this offlining scenario, the code tolerates such
+ * lags. It will function correctly even if a channel interrupt comes
+ * in on a CPU that is different from the channel target_cpu value.
+ */
+
+ channel->target_cpu = target_cpu;
+ channel->target_vp = hv_cpu_number_to_vp_number(target_cpu);
+ channel->numa_node = cpu_to_node(target_cpu);
+
+ /* See init_vp_index(). */
+ if (hv_is_perf_channel(channel))
+ hv_update_alloced_cpus(origin_cpu, target_cpu);
+
+ /* Currently set only for storvsc channels. */
+ if (channel->change_target_cpu_callback) {
+ (*channel->change_target_cpu_callback)(channel,
+ origin_cpu, target_cpu);
+ }
+
+cpu_store_unlock:
+ mutex_unlock(&vmbus_connection.channel_mutex);
+ cpus_read_unlock();
+ return ret;
+}
+static VMBUS_CHAN_ATTR(cpu, 0644, target_cpu_show, target_cpu_store);
static ssize_t channel_pending_show(struct vmbus_channel *channel,
char *buf)
@@ -1830,7 +1998,7 @@ int vmbus_device_register(struct hv_device *child_device_obj)
int ret;
dev_set_name(&child_device_obj->device, "%pUl",
- child_device_obj->channel->offermsg.offer.if_instance.b);
+ &child_device_obj->channel->offermsg.offer.if_instance);
child_device_obj->device.bus = &hv_bus;
child_device_obj->device.parent = &hv_acpi_dev->dev;
@@ -2221,9 +2389,12 @@ static int vmbus_bus_suspend(struct device *dev)
list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
/*
- * Invalidate the field. Upon resume, vmbus_onoffer() will fix
- * up the field, and the other fields (if necessary).
+ * Remove the channel from the array of channels and invalidate
+ * the channel's relid. Upon resume, vmbus_onoffer() will fix
+ * up the relid (and other fields, if necessary) and add the
+ * channel back to the array.
*/
+ vmbus_channel_unmap_relid(channel);
channel->offermsg.child_relid = INVALID_RELID;
if (is_hvsock_channel(channel)) {
@@ -2470,6 +2641,7 @@ static void __exit vmbus_exit(void)
hv_debug_rm_all_dir();
vmbus_free_channels();
+ kfree(vmbus_connection.channels);
if (ms_hyperv.misc_features & HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE) {
kmsg_dump_unregister(&hv_kmsg_dumper);