Fix a regression where hv_root_crash_init() fails a hypercall because
the hypercall page is not fully setup. The regression is caused by
following commit:

commit c8ed0812646e ("x86/hyperv: Use direct call to hypercall-page")

Fix is simple, just move the crash init call after the hypercall
page setup.

Signed-off-by: Mukesh R <mrathor@linux.microsoft.com>
---
 arch/x86/hyperv/hv_init.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index 14de43f4bc6c..7f3301bd081e 100644
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -558,7 +558,6 @@ void __init hyperv_init(void)
 		memunmap(src);
 
 		hv_remap_tsc_clocksource();
-		hv_root_crash_init();
 		hv_sleep_notifiers_register();
 	} else {
 		hypercall_msr.guest_physical_address = vmalloc_to_pfn(hv_hypercall_pg);
@@ -567,6 +566,9 @@ void __init hyperv_init(void)
 
 	hv_set_hypercall_pg(hv_hypercall_pg);
 
+	if (hv_root_partition())        /* after set hypercall pg */
+		hv_root_crash_init();
+
 skip_hypercall_pg_init:
 	/*
 	 * hyperv_init() is called before LAPIC is initialized: see
-- 
2.51.2.vfs.0.1

On 2/3/2026 2:41 PM, Mukesh R wrote:
> Fix a regression where hv_root_crash_init() fails a hypercall because
> the hypercall page is not fully setup. The regression is caused by
> following commit:
> 
> commit c8ed0812646e ("x86/hyperv: Use direct call to hypercall-page")
> 

Is that the right commit? The named commit was merged in v6.18-rc1 and
hv_root_crash_init() was only merged in v6.19-rc1...

Thanks,
Easwar (he/him)

On 2/3/26 16:25, Easwar Hariharan wrote:
> On 2/3/2026 2:41 PM, Mukesh R wrote:
>> Fix a regression where hv_root_crash_init() fails a hypercall because
>> the hypercall page is not fully setup. The regression is caused by
>> following commit:
>>
>> commit c8ed0812646e ("x86/hyperv: Use direct call to hypercall-page")
>>
> 
> Is that the right commit? The named commit was merged in v6.18-rc1 and
> hv_root_crash_init() was only merged in v6.19-rc1...
> 
> Thanks,
> Easwar (he/him)

Ah, you are right. I guess that commit was not in our internal
hyper-next mirror, so testing did not reveal the issue and I did not
notice it. Because of few missing things, we've to use internal mirror
to test. Anyways, will fix the commit and resend.

Thanks,
-Mukesh