linux-kernel - Re: [PATCH 5/8] xen/pvh: Prevent PVH guests from using PIC, RTC and IOAPIC

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Date:   Wed, 26 Oct 2016 12:42:05 +0200
From:   Roger Pau Monné <roger.pau@...rix.com>
To:     Boris Ostrovsky <boris.ostrovsky@...cle.com>
CC:     <david.vrabel@...rix.com>, <JGross@...e.com>,
        <linux-kernel@...r.kernel.org>, <xen-devel@...ts.xenproject.org>
Subject: Re: [PATCH 5/8] xen/pvh: Prevent PVH guests from using PIC, RTC and
 IOAPIC

On Fri, Oct 14, 2016 at 02:05:15PM -0400, Boris Ostrovsky wrote:
> Make sure they don't use these devices since they are not emulated
> for unprivileged PVH guest.
> 
> Also don't initialize hypercall page for them in init_hvm_pv_info()
> since this has already been done.
> 
> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@...cle.com>
> ---
>  arch/x86/xen/enlighten.c | 24 +++++++++++++++++-------
>  1 file changed, 17 insertions(+), 7 deletions(-)
> 
> diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
> index d38d568..6c1a330 100644
> --- a/arch/x86/xen/enlighten.c
> +++ b/arch/x86/xen/enlighten.c
> @@ -1803,10 +1803,21 @@ static void __init init_hvm_pv_info(void)
>  	minor = eax & 0xffff;
>  	printk(KERN_INFO "Xen version %d.%d.\n", major, minor);
>  
> -	cpuid(base + 2, &pages, &msr, &ecx, &edx);
> +	xen_domain_type = XEN_HVM_DOMAIN;
>  
> -	pfn = __pa(hypercall_page);
> -	wrmsr_safe(msr, (u32)pfn, (u32)(pfn >> 32));
> +	/* PVH set up hypercall page earlier in xen_prepare_pvh() */
> +	if (xen_pvh_domain()) {
> +		pv_info.name = "Xen PVH";
> +#ifdef CONFIG_ACPI
> +		/* No PIC or IOAPIC */

Shouldn't this be fetched from the MADT ACPI table if ACPI is available 
(rsdp_paddr != 0 in start_info)?

Roger.