Re: [RFC] xen/pvh: detect PVH after kexec

[Boris Ostrovsky <boris.ostrovsky@oracle.com>]

On 03/20/2017 02:20 PM, Vitaly Kuznetsov wrote:
> PVH guests after kexec boot like normal HVM guests and we're not entering
> xen_prepare_pvh()

Is it not? Aren't we going via xen_hvm_shutdown() and then
SHUTDOWN_soft_reset which would restart at the same entry point as
regular boot?

-boris


>  but we still want to know that we're PVH. This hack does
> the job by using XEN_IOPORT_MAGIC but I didn't find any straitforward way
> to do it. Did I miss something? Or shall we introduce a CPUID leaf or
> something like that?
>
> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
> ---
>  arch/x86/xen/enlighten.c | 18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
>
> diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
> index ec1d5c4..4a30886 100644
> --- a/arch/x86/xen/enlighten.c
> +++ b/arch/x86/xen/enlighten.c
> @@ -51,6 +51,7 @@
>  #include <xen/hvm.h>
>  #include <xen/hvc-console.h>
>  #include <xen/acpi.h>
> +#include <xen/platform_pci.h>
>  
>  #include <asm/paravirt.h>
>  #include <asm/apic.h>
> @@ -1765,6 +1766,20 @@ void __init xen_prepare_pvh(void)
>  
>  	x86_init.oem.arch_setup = xen_pvh_arch_setup;
>  }
> +
> +static void xen_detect_pvh(void)
> +{
> +	short magic;
> +
> +	if (xen_pvh)
> +		return;
> +
> +	magic = inw(XEN_IOPORT_MAGIC);
> +	if (magic != XEN_IOPORT_MAGIC_VAL) {
> +		xen_pvh = 1;
> +		xen_pvh_arch_setup();
> +	}
> +}
>  #endif
>  
>  void __ref xen_hvm_init_shared_info(void)
> @@ -1912,6 +1927,9 @@ static void __init xen_hvm_guest_init(void)
>  
>  	init_hvm_pv_info();
>  
> +	/* Detect PVH booting after kexec */
> +	xen_detect_pvh();
> +
>  	xen_hvm_init_shared_info();
>  
>  	xen_panic_handler_init();


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