From mboxrd@z Thu Jan  1 00:00:00 1970
From: Keir Fraser <keir.xen@gmail.com>
Subject: Re: [PATCH] tools/hvmloader: move shared_info to
 reserved memory area
Date: Fri, 26 Oct 2012 09:08:51 -0700
Message-ID: <CCB003A3.42962%keir.xen@gmail.com>
References: <20121026155128.GA18615@aepfle.de>
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To: Olaf Hering <olaf@aepfle.de>, Konrad Rzeszutek Wilk <konrad@kernel.org>
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On 26/10/2012 08:51, "Olaf Hering" <olaf@aepfle.de> wrote:

> On Fri, Oct 26, Olaf Hering wrote:
> 
>> Oh, my take would be to return false in xen_hvm_platform if the
>> hypervisor is 3.3 or older, so that the guest does not use the PVonHVM
>> extensions.
> 
> Like this untested patch:

Looks okay to me.

 -- Keir

> diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
> index 0cc41f8..8566fa8 100644
> --- a/arch/x86/xen/enlighten.c
> +++ b/arch/x86/xen/enlighten.c
> @@ -1543,17 +1543,10 @@ static void __init xen_hvm_init_shared_info(void)
>  
>  static void __init init_hvm_pv_info(void)
>  {
> - int major, minor;
> uint32_t eax, ebx, ecx, edx, pages, msr, base;
> u64 pfn;
>  
> base = xen_cpuid_base();
> - cpuid(base + 1, &eax, &ebx, &ecx, &edx);
> -
> - major = eax >> 16;
> - minor = eax & 0xffff;
> - printk(KERN_INFO "Xen version %d.%d.\n", major, minor);
> -
> cpuid(base + 2, &pages, &msr, &ecx, &edx);
>  
> pfn = __pa(hypercall_page);
> @@ -1604,13 +1597,29 @@ static void __init xen_hvm_guest_init(void)
>  
>  static bool __init xen_hvm_platform(void)
>  {
> + int major, minor, old = 0;
> + uint32_t eax, ebx, ecx, edx, base;
> + bool usable = true;
> +
> if (xen_pv_domain())
> return false;
>  
> - if (!xen_cpuid_base())
> + base = xen_cpuid_base();
> + if (!base)
> return false;
>  
> - return true;
> + cpuid(base + 1, &eax, &ebx, &ecx, &edx);
> +
> + major = eax >> 16;
> + minor = eax & 0xffff;
> +
> + /* Require at least Xen 3.4 */
> + if (major < 3 || (major == 3 && minor < 4))
> +  usable = false;
> + printk(KERN_INFO "Xen version %d.%d.%s\n",
> +  major, minor, usable ? "" : " (too old)");
> +
> + return usable;
>  }
>  
>  bool xen_hvm_need_lapic(void)