Re: [PATCH v2 3/3] xen: share start flags between PV and PVH

From: Stefano Stabellini
Date: Wed May 09 2018 - 17:47:33 EST


On Wed, 9 May 2018, Roger Pau Monne wrote:
> Use a global variable to store the start flags for both PV and PVH.
> This allows the xen_initial_domain macro to work properly on PVH.
>
> Note that ARM is also switched to use the new variable.
>
> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
> Signed-off-by: Roger Pau Monnà <roger.pau@xxxxxxxxxx>
> ---
> Cc: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
> Cc: Juergen Gross <jgross@xxxxxxxx>
> Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx
> ---
> Changes since v1:
> - Switch ARM to also use the new xen_start_flags.

The ARM side looks good


> ---
> arch/arm/xen/enlighten.c | 7 ++++---
> arch/x86/xen/enlighten.c | 7 +++++++
> arch/x86/xen/enlighten_pv.c | 1 +
> arch/x86/xen/enlighten_pvh.c | 1 +
> include/xen/xen.h | 4 +++-
> 5 files changed, 16 insertions(+), 4 deletions(-)
>
> diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c
> index ba7f4c8f5c3e..a99d5edf7bdf 100644
> --- a/arch/arm/xen/enlighten.c
> +++ b/arch/arm/xen/enlighten.c
> @@ -59,6 +59,9 @@ struct xen_memory_region xen_extra_mem[XEN_EXTRA_MEM_MAX_REGIONS] __initdata;
>
> static __read_mostly unsigned int xen_events_irq;
>
> +uint32_t xen_start_flags;
> +EXPORT_SYMBOL(xen_start_flags);
> +
> int xen_remap_domain_gfn_array(struct vm_area_struct *vma,
> unsigned long addr,
> xen_pfn_t *gfn, int nr,
> @@ -282,9 +285,7 @@ void __init xen_early_init(void)
> xen_setup_features();
>
> if (xen_feature(XENFEAT_dom0))
> - xen_start_info->flags |= SIF_INITDOMAIN|SIF_PRIVILEGED;
> - else
> - xen_start_info->flags &= ~(SIF_INITDOMAIN|SIF_PRIVILEGED);
> + xen_start_flags |= SIF_INITDOMAIN|SIF_PRIVILEGED;
>
> if (!console_set_on_cmdline && !xen_initial_domain())
> add_preferred_console("hvc", 0, NULL);
> diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
> index c9081c6671f0..3b5318505c69 100644
> --- a/arch/x86/xen/enlighten.c
> +++ b/arch/x86/xen/enlighten.c
> @@ -64,6 +64,13 @@ struct shared_info xen_dummy_shared_info;
> __read_mostly int xen_have_vector_callback;
> EXPORT_SYMBOL_GPL(xen_have_vector_callback);
>
> +/*
> + * NB: needs to live in .data because it's used by xen_prepare_pvh which runs
> + * before clearing the bss.
> + */
> +uint32_t xen_start_flags __attribute__((section(".data"))) = 0;
> +EXPORT_SYMBOL(xen_start_flags);
> +
> /*
> * Point at some empty memory to start with. We map the real shared_info
> * page as soon as fixmap is up and running.
> diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
> index c36d23aa6c35..04a6914b8b85 100644
> --- a/arch/x86/xen/enlighten_pv.c
> +++ b/arch/x86/xen/enlighten_pv.c
> @@ -1227,6 +1227,7 @@ asmlinkage __visible void __init xen_start_kernel(void)
> return;
>
> xen_domain_type = XEN_PV_DOMAIN;
> + xen_start_flags = xen_start_info->flags;
>
> xen_setup_features();
>
> diff --git a/arch/x86/xen/enlighten_pvh.c b/arch/x86/xen/enlighten_pvh.c
> index e039d1809809..2653eb9b5dd8 100644
> --- a/arch/x86/xen/enlighten_pvh.c
> +++ b/arch/x86/xen/enlighten_pvh.c
> @@ -98,6 +98,7 @@ void __init xen_prepare_pvh(void)
> }
>
> xen_pvh = 1;
> + xen_start_flags = pvh_start_info.flags;
>
> wrmsr_safe(MSR_MTRRdefType, 0x800 | MTRR_TYPE_WRBACK, 0);
>
> diff --git a/include/xen/xen.h b/include/xen/xen.h
> index 9d4340c907d1..15fa01c50a53 100644
> --- a/include/xen/xen.h
> +++ b/include/xen/xen.h
> @@ -29,8 +29,10 @@ extern bool xen_pvh;
> #include <xen/interface/xen.h>
> #include <asm/xen/hypervisor.h>
>
> +extern uint32_t xen_start_flags;
> +
> #define xen_initial_domain() (xen_domain() && \
> - xen_start_info && xen_start_info->flags & SIF_INITDOMAIN)
> + (xen_start_flags & SIF_INITDOMAIN))
> #else /* !CONFIG_XEN_DOM0 */
> #define xen_initial_domain() (0)
> #endif /* CONFIG_XEN_DOM0 */
> --
> 2.17.0
>