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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Michael Kelley <mikelley@microsoft.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Dexuan Cui <decui@microsoft.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.4 103/191] Drivers: hv: vmbus: Fix crash handler reset of Hyper-V synic
Date:   Thu,  2 Jan 2020 23:06:25 +0100
Message-Id: <20200102215840.970579601@linuxfoundation.org>
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From: Michael Kelley <mikelley@microsoft.com>

[ 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
shutdown.

Signed-off-by: Michael Kelley <mikelley@microsoft.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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_stimer_cleanup(cpu);
-	hv_synic_cleanup(cpu);
+	hv_synic_disable_regs(cpu);
 	hyperv_cleanup();
 };
 
-- 
2.20.1