Re: [PATCH v2 1/3] x86/xen: use clear_bss() for Xen PV guests

From: Jan Beulich
Date: Thu Jun 23 2022 - 05:51:53 EST


On 23.06.2022 11:46, Juergen Gross wrote:
> --- a/arch/x86/xen/enlighten_pv.c
> +++ b/arch/x86/xen/enlighten_pv.c
> @@ -1183,15 +1183,19 @@ static void __init xen_domu_set_legacy_features(void)
> extern void early_xen_iret_patch(void);
>
> /* First C function to be called on Xen boot */
> -asmlinkage __visible void __init xen_start_kernel(void)
> +asmlinkage __visible void __init xen_start_kernel(struct start_info *si)
> {
> struct physdev_set_iopl set_iopl;
> unsigned long initrd_start = 0;
> int rc;
>
> - if (!xen_start_info)
> + if (!si)
> return;
>
> + clear_bss();

As per subsequent observation, this shouldn't really be needed: The
hypervisor (or tool stack for DomU-s) already does so. While I guess
we want to keep it to be on the safe side, maybe worth a comment?

Jan