linux-kernel - Re: [PATCH] xen: vcpu_info reinit error after 'xl save -c' & 'xl restore' on PVOPS VM which has multi-cpu

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Date:	Sat, 25 Apr 2015 19:31:58 -0400
From:	Boris Ostrovsky <boris.ostrovsky@...cle.com>
To:	"Ouyang Zhaowei (Charles)" <ouyangzhaowei@...wei.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	David Vrabel <david.vrabel@...rix.com>
CC:	linux-kernel@...r.kernel.org,
	Dingweiping <weiping.ding@...wei.com>,
	Yanqiangjun <yanqiangjun@...wei.com>, jinjian@...wei.com
Subject: Re: [PATCH] xen: vcpu_info reinit error after 'xl save -c' & 'xl
 restore' on PVOPS VM which has multi-cpu


On 04/24/2015 05:30 AM, Ouyang Zhaowei (Charles) wrote:
> If a PVOPS VM has multi-cpu the vcpu_info of cpu0 is the member of the structure HYPERVISOR_shared_info,
> and the others is not, but after 'xl save -c/restore' the vcpu_info will be reinitialized,
> the vcpu_info of all the vcpus will be considered as the member of HYPERVISOR_shared_info.
> This will cause the cpu1 and other cpu keep receiving interrupts, and the cpu0 is waiting them to
> finish the job.
> So we do not reinit the vcpu_info when PVOPS vm is doing 'xl save -c/restore'.
>
> Signed-off-by: Charles Ouyang <ouyangzhaowei@...wei.com>
> ---
>   arch/x86/xen/suspend.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/xen/suspend.c b/arch/x86/xen/suspend.c
> index d949769..b2bed45 100644
> --- a/arch/x86/xen/suspend.c
> +++ b/arch/x86/xen/suspend.c
> @@ -32,7 +32,8 @@ static void xen_hvm_post_suspend(int suspend_cancelled)
>   {
>   #ifdef CONFIG_XEN_PVHVM
>          int cpu;
> -       xen_hvm_init_shared_info();
> +       if (!suspend_cancelled)
> +               xen_hvm_init_shared_info();
>          xen_callback_vector();
>          xen_unplug_emulated_devices();
>          if (xen_feature(XENFEAT_hvm_safe_pvclock)) {

Do we need to call other routines if suspend is canceled?

Also, if suspend is canceled then we don't do xen_irq_resume() if that's 
what you meant by "vcpu_info will be reinitialized". Were you referring 
some other re-initialization?

(The patch itself looks like the right thing to do though).

-boris
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