[PATCH 5.4 103/191] Drivers: hv: vmbus: Fix crash handler reset of Hyper-V synic

From: Greg Kroah-Hartman
Date: Thu Jan 02 2020 - 17:59:04 EST

From: Michael Kelley <mikelley@xxxxxxxxxxxxx>

[ Upstream commit 7a1323b5dfe44a9013a2cc56ef2973034a00bf88 ]

The crash handler calls hv_synic_cleanup() to shutdown the
Hyper-V synthetic interrupt controller. But if the CPU
that calls hv_synic_cleanup() has a VMbus channel interrupt
assigned to it (which is likely the case in smaller VM sizes),
hv_synic_cleanup() returns an error and the synthetic
interrupt controller isn't shutdown. While the lack of
being shutdown hasn't caused a known problem, it still
should be fixed for highest reliability.

So directly call hv_synic_disable_regs() instead of
hv_synic_cleanup(), which ensures that the synic is always

Signed-off-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>
Reviewed-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
Reviewed-by: Dexuan Cui <decui@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
drivers/hv/vmbus_drv.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 53a60c81e220..05ead1735c6e 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -2308,7 +2308,7 @@ static void hv_crash_handler(struct pt_regs *regs)
vmbus_connection.conn_state = DISCONNECTED;
cpu = smp_processor_id();
- hv_synic_cleanup(cpu);
+ hv_synic_disable_regs(cpu);