2016-10-02 22:50:49

by Boris Ostrovsky

Subject: [PATCH] xen/x86: Initialize per_cpu(xen_vcpu, 0) a little earlier

xen_cpuhp_setup() calls mutex_lock() which, when CONFIG_DEBUG_MUTEXES
is defined, ends up calling xen_save_fl(). That routine expects
per_cpu(xen_vcpu, 0) to be already initialized.

Signed-off-by: Boris Ostrovsky <[email protected]>
Reported-by: Sander Eikelenboom <[email protected]>
---
Sander, please see if this fixes the problem. Thanks.


arch/x86/xen/enlighten.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 366b6ae..96c2dea 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1644,7 +1644,6 @@ asmlinkage __visible void __init xen_start_kernel(void)
xen_initial_gdt = &per_cpu(gdt_page, 0);

xen_smp_init();
- WARN_ON(xen_cpuhp_setup());

#ifdef CONFIG_ACPI_NUMA
/*
@@ -1658,6 +1657,8 @@ asmlinkage __visible void __init xen_start_kernel(void)
possible map and a non-dummy shared_info. */
per_cpu(xen_vcpu, 0) = &HYPERVISOR_shared_info->vcpu_info[0];

+ WARN_ON(xen_cpuhp_setup());
+
local_irq_disable();
early_boot_irqs_disabled = true;

--
1.8.3.1

2016-10-03 08:42:18

by Sander Eikelenboom

Subject: Re: [PATCH] xen/x86: Initialize per_cpu(xen_vcpu, 0) a little earlier

On 2016-10-03 00:45, Boris Ostrovsky wrote:
> xen_cpuhp_setup() calls mutex_lock() which, when CONFIG_DEBUG_MUTEXES
> is defined, ends up calling xen_save_fl(). That routine expects
> per_cpu(xen_vcpu, 0) to be already initialized.
>
> Signed-off-by: Boris Ostrovsky <[email protected]>
> Reported-by: Sander Eikelenboom <[email protected]>
> ---
> Sander, please see if this fixes the problem. Thanks.

Hi Boris,

I have tested it and it fixes the dom0 crash in early boot for me.
Thanks again for investigating and the swift fix !

--
Sander


> arch/x86/xen/enlighten.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
> index 366b6ae..96c2dea 100644
> --- a/arch/x86/xen/enlighten.c
> +++ b/arch/x86/xen/enlighten.c
> @@ -1644,7 +1644,6 @@ asmlinkage __visible void __init
> xen_start_kernel(void)
> xen_initial_gdt = &per_cpu(gdt_page, 0);
>
> xen_smp_init();
> - WARN_ON(xen_cpuhp_setup());
>
> #ifdef CONFIG_ACPI_NUMA
> /*
> @@ -1658,6 +1657,8 @@ asmlinkage __visible void __init
> xen_start_kernel(void)
> possible map and a non-dummy shared_info. */
> per_cpu(xen_vcpu, 0) = &HYPERVISOR_shared_info->vcpu_info[0];
>
> + WARN_ON(xen_cpuhp_setup());
> +
> local_irq_disable();
> early_boot_irqs_disabled = true;

2016-10-05 09:48:41

by David Vrabel

Subject: Re: [Xen-devel] [PATCH] xen/x86: Initialize per_cpu(xen_vcpu, 0) a little earlier

On 02/10/16 23:45, Boris Ostrovsky wrote:
> xen_cpuhp_setup() calls mutex_lock() which, when CONFIG_DEBUG_MUTEXES
> is defined, ends up calling xen_save_fl(). That routine expects
> per_cpu(xen_vcpu, 0) to be already initialized.

Applied to for-linus-4.9, thanks.

David