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

MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/merge_requests/2034

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2168542

    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>
    (cherry picked from commit 32c97d9)

Signed-off-by: Mohamed Gamal Morsy <mgamal@redhat.com>

Approved-by: Cathy Avery <cavery@redhat.com>
Approved-by: Vitaly Kuznetsov <vkuznets@redhat.com>

Signed-off-by: Herton R. Krzesinski <herton@redhat.com>

Author: Herton R. Krzesinski

arch/x86/hyperv/hv_init.c

@@ -535,8 +535,6 @@ 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);