diff options
| -rw-r--r-- | drivers/hv/hv.c | 56 |
1 files changed, 53 insertions, 3 deletions
diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c index 3e6ff83adff4..e0c522d143a3 100644 --- a/drivers/hv/hv.c +++ b/drivers/hv/hv.c @@ -15,6 +15,7 @@ #include <linux/hyperv.h> #include <linux/random.h> #include <linux/clockchips.h> +#include <linux/delay.h> #include <linux/interrupt.h> #include <clocksource/hyperv_timer.h> #include <asm/mshyperv.h> @@ -292,12 +293,50 @@ void hv_synic_disable_regs(unsigned int cpu) disable_percpu_irq(vmbus_irq); } +#define HV_MAX_TRIES 3 +/* + * Scan the event flags page of 'this' CPU looking for any bit that is set. If we find one + * bit set, then wait for a few milliseconds. Repeat these steps for a maximum of 3 times. + * Return 'true', if there is still any set bit after this operation; 'false', otherwise. + * + * If a bit is set, that means there is a pending channel interrupt. The expectation is + * that the normal interrupt handling mechanism will find and process the channel interrupt + * "very soon", and in the process clear the bit. + */ +static bool hv_synic_event_pending(void) +{ + struct hv_per_cpu_context *hv_cpu = this_cpu_ptr(hv_context.cpu_context); + union hv_synic_event_flags *event = + (union hv_synic_event_flags *)hv_cpu->synic_event_page + VMBUS_MESSAGE_SINT; + unsigned long *recv_int_page = event->flags; /* assumes VMBus version >= VERSION_WIN8 */ + bool pending; + u32 relid; + int tries = 0; + +retry: + pending = false; + for_each_set_bit(relid, recv_int_page, HV_EVENT_FLAGS_COUNT) { + /* Special case - VMBus channel protocol messages */ + if (relid == 0) + continue; + pending = true; + break; + } + if (pending && tries++ < HV_MAX_TRIES) { + usleep_range(10000, 20000); + goto retry; + } + return pending; +} int hv_synic_cleanup(unsigned int cpu) { struct vmbus_channel *channel, *sc; bool channel_found = false; + if (vmbus_connection.conn_state != CONNECTED) + goto always_cleanup; + /* * Hyper-V does not provide a way to change the connect CPU once * it is set; we must prevent the connect CPU from going offline @@ -305,8 +344,7 @@ int hv_synic_cleanup(unsigned int cpu) * path where the vmbus is already disconnected, the CPU must be * allowed to shut down. */ - if (cpu == VMBUS_CONNECT_CPU && - vmbus_connection.conn_state == CONNECTED) + if (cpu == VMBUS_CONNECT_CPU) return -EBUSY; /* @@ -333,9 +371,21 @@ int hv_synic_cleanup(unsigned int cpu) } mutex_unlock(&vmbus_connection.channel_mutex); - if (channel_found && vmbus_connection.conn_state == CONNECTED) + if (channel_found) + return -EBUSY; + + /* + * channel_found == false means that any channels that were previously + * assigned to the CPU have been reassigned elsewhere with a call of + * vmbus_send_modifychannel(). Scan the event flags page looking for + * bits that are set and waiting with a timeout for vmbus_chan_sched() + * to process such bits. If bits are still set after this operation + * and VMBus is connected, fail the CPU offlining operation. + */ + if (vmbus_proto_version >= VERSION_WIN10_V4_1 && hv_synic_event_pending()) return -EBUSY; +always_cleanup: hv_stimer_legacy_cleanup(cpu); hv_synic_disable_regs(cpu); |