Re: [Xen-devel] [PATCH] xen PVonHVM: require at least Xen 3.4 as dom0

[Pasi Kärkkäinen <pasik@xxxxxx>]

On Tue, Oct 30, 2012 at 05:05:05PM +0100, Olaf Hering wrote:
> The XenPVHVM extensions have not been tested much on very old
> hypervisors. At least Xen 3.4 gets some testing with the pvops kernel.
> 
> Require at least Xen 3.4 for the PVonHVM extensions. If an older
> hypervisor is detected the extensions will be disabled and the guest
> will only see emulated hardware.
> 
> Signed-off-by: Olaf Hering <olaf@xxxxxxxxx>
>

IIRC upstream Linux PVonHVM drivers do work OK today on RHEL5 Xen, 
which advertises itself as Xen 3.1.2-based..


-- Pasi


> ---
>  arch/x86/xen/enlighten.c | 27 ++++++++++++++++++---------
>  1 file changed, 18 insertions(+), 9 deletions(-)
> 
> 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)
> -- 
> 1.8.0
> 
> 
> _______________________________________________
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> Xen-devel@xxxxxxxxxxxxx
> http://lists.xen.org/xen-devel

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