On Mon, 20 Nov 2023, Stefano Stabellini wrote:
> On Mon, 20 Nov 2023, Juergen Gross wrote:
> > On 20.11.23 03:21, osstest service owner wrote:
> > > flight 183794 linux-linus real [real]
> > > http://logs.test-lab.xenproject.org/osstest/logs/183794/
> > >
> > > Regressions :-(
> > >
> > > Tests which did not succeed and are blocking,
> > > including tests which could not be run:
> > > test-arm64-arm64-examine 8 reboot fail REGR. vs.
> > > 183766
> >
> > I'm seeing the following in the serial log:
> >
> > Nov 20 00:25:41.586712 [ 0.567318] kernel BUG at
> > arch/arm64/xen/../../arm/xen/enlighten.c:164!
> > Nov 20 00:25:41.598711 [ 0.574002] Internal error: Oops - BUG:
> > 00000000f2000800 [#1] PREEMPT SMP
> >
> > The related source code lines in the kernel are:
> >
> > ········err = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_info,
> > xen_vcpu_nr(cpu),
> > ································ &info);
> > ········BUG_ON(err);
> >
> > I suspect commit 20f3b8eafe0ba to be the culprit.
> >
> > Stefano, could you please have a look?
The good news and bad news is that I cannot repro this neither with nor
without CONFIG_UNMAP_KERNEL_AT_EL0. I looked at commit 20f3b8eafe0ba but
I cannot see anything wrong with it. Looking at the register dump, from:
x0 : fffffffffffffffa
I am guessing the error was -ENXIO which is returned from map_guest_area
in Xen.
Could it be that the struct is crossing a page boundary? Or that it is
not 64-bit aligned? Do we need to do something like the following?
diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c
index 9afdc4c4a5dc..5326070c5dc0 100644
--- a/arch/arm/xen/enlighten.c
+++ b/arch/arm/xen/enlighten.c
@@ -484,7 +485,7 @@ static int __init xen_guest_init(void)
* for secondary CPUs as they are brought up.
* For uniformity we use VCPUOP_register_vcpu_info even on cpu0.
*/
- xen_vcpu_info = alloc_percpu(struct vcpu_info);
+ xen_vcpu_info = __alloc_percpu(struct vcpu_info, PAGE_SIZE);
if (xen_vcpu_info == NULL)
return -ENOMEM;
