git: 200d47320207 - stable/13 - hyperv: Register the MSR-based timecounter during SI_SUB_HYPERVISOR

The branch stable/13 has been updated by markj:

URL: https://cgit.FreeBSD.org/src/commit/?id=200d4732020742eb17f51b6e1c553cfac878a559

commit 200d4732020742eb17f51b6e1c553cfac878a559
Author:     Mark Johnston <markj@FreeBSD.org>
AuthorDate: 2021-11-19 22:30:05 +0000
Commit:     Mark Johnston <markj@FreeBSD.org>
CommitDate: 2021-11-22 13:45:34 +0000

    hyperv: Register the MSR-based timecounter during SI_SUB_HYPERVISOR
    
    This reverts commit 9ef7df022a46 ("hyperv: Register hyperv_timecounter
    later during boot") and adds a comment explaining why the timecounter
    needs to be registered as early as it is.
    
    PR:             259878
    Fixes:  9ef7df022a46 ("hyperv: Register hyperv_timecounter later during boot")
    Reviewed by:    kib
    Sponsored by:   The FreeBSD Foundation
    
    (cherry picked from commit ed6a9452be01c1b7805d0a7311211b8cf381a9dd)
---
 sys/dev/hyperv/vmbus/hyperv.c | 16 +++++++---------
 1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/sys/dev/hyperv/vmbus/hyperv.c b/sys/dev/hyperv/vmbus/hyperv.c
index 2c413664cd07..01e0ad9610d9 100644
--- a/sys/dev/hyperv/vmbus/hyperv.c
+++ b/sys/dev/hyperv/vmbus/hyperv.c
@@ -247,15 +247,12 @@ hyperv_init(void *dummy __unused)
 	/* Set guest id */
 	wrmsr(MSR_HV_GUEST_OS_ID, MSR_HV_GUESTID_FREEBSD);
 
-}
-SYSINIT(hyperv_initialize, SI_SUB_HYPERVISOR, SI_ORDER_FIRST, hyperv_init,
-    NULL);
-
-static void
-hyperv_tc_init(void *arg __unused)
-{
 	if (hyperv_features & CPUID_HV_MSR_TIME_REFCNT) {
-		/* Register Hyper-V timecounter */
+		/*
+		 * Register Hyper-V timecounter.  This should be done as early
+		 * as possible to let DELAY() work, since the 8254 PIT is not
+		 * reliably emulated or even available.
+		 */
 		tc_init(&hyperv_timecounter);
 
 		/*
@@ -265,7 +262,8 @@ hyperv_tc_init(void *arg __unused)
 		hyperv_tc64 = hyperv_tc64_rdmsr;
 	}
 }
-SYSINIT(hyperv_tc_init, SI_SUB_DRIVERS, SI_ORDER_FIRST, hyperv_tc_init, NULL);
+SYSINIT(hyperv_initialize, SI_SUB_HYPERVISOR, SI_ORDER_FIRST, hyperv_init,
+    NULL);
 
 static void
 hypercall_memfree(void)