Merge tag 'arm-newsoc-5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc

[linux-2.6-block.git] / drivers / hv / hv.c

diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
index 3e6ff83adff423b44933dcaf1927a85c402227b3..e83507f49676ddd221abda1cdb9e1d8d28af5edf 100644 (file)
--- 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>
@@ -104,7 +105,7 @@ int hv_post_message(union hv_connection_id connection_id,
         */
        put_cpu_ptr(hv_cpu);
 
-       return status & 0xFFFF;
+       return hv_result(status);
 }
 
 int hv_synic_alloc(void)
@@ -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);