x86/hyperv: Remove unregister syscore call from Hyper-V cleanup

Hyper-V cleanup code comes under panic path where preemption and irq
is already disabled. So calling of unregister_syscore_ops might schedule
out the thread even for the case where mutex lock is free.
hyperv_cleanup
	unregister_syscore_ops
			mutex_lock(&syscore_ops_lock)
				might_sleep
Here might_sleep might schedule out this thread, where voluntary preemption
config is on and this thread will never comes back. And also this was added
earlier to maintain the symmetry which is not required as this can comes
during crash shutdown path only.

To prevent the same, removing unregister_syscore_ops function call.

Signed-off-by: Gaurav Kohli <gauravkohli@linux.microsoft.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/1669443291-2575-1-git-send-email-gauravkohli@linux.microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>

diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index a823fde1ad7f3f1c921178374c0e0258b1ac4fe4..41ef036ebb7bae50e4818fe4cbf125c8aa6a1f2a 100644 (file)
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -537,8 +537,6 @@ void hyperv_cleanup(void)
        union hv_x64_msr_hypercall_contents hypercall_msr;
        union hv_reference_tsc_msr tsc_msr;
 
-       unregister_syscore_ops(&hv_syscore_ops);
-
        /* Reset our OS id */
        wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
        hv_ghcb_msr_write(HV_X64_MSR_GUEST_OS_ID, 0);