linux-kernel - [PATCH 1/1] Drivers: hv: vmbus: Fix crash handler reset of Hyper-V synic

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Date:   Thu, 14 Nov 2019 06:32:01 +0000
From:   Michael Kelley <mikelley@...rosoft.com>
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        vkuznets <vkuznets@...hat.com>,
        KY Srinivasan <kys@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        "sashal@...nel.org" <sashal@...nel.org>,
        Dexuan Cui <decui@...rosoft.com>,
        "linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>
CC:     Michael Kelley <mikelley@...rosoft.com>
Subject: [PATCH 1/1] Drivers: hv: vmbus: Fix crash handler reset of Hyper-V
 synic

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
shutdown.

Signed-off-by: Michael Kelley <mikelley@...rosoft.com>
---
 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 664a415..665920d 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -2305,7 +2305,7 @@ static void hv_crash_handler(struct pt_regs *regs)
 	vmbus_connection.conn_state = DISCONNECTED;
 	cpu = smp_processor_id();
 	hv_stimer_cleanup(cpu);
-	hv_synic_cleanup(cpu);
+	hv_synic_disable_regs(cpu);
 	hyperv_cleanup();
 };

-- 
1.8.3.1