Re: [Xen-devel] [PATCH v5 4/4] x86/xen: Add "nopv" support for HVM guest

2019-07-08 Thread Zhenzhong Duan


On 2019/7/5 21:06, Boris Ostrovsky wrote:

On 7/2/19 9:19 PM, Zhenzhong Duan wrote:

PVH guest needs PV extentions to work, so "nopv" parameter should be
ignored for PVH but not for HVM guest.

If PVH guest boots up via the Xen-PVH boot entry, xen_pvh is set early,
we know it's PVH guest and ignore "nopv" parameter directly.

If PVH guest boots up via the normal boot entry same as HVM guest, it's
hard to distinguish PVH and HVM guest at that time.

To handle that case, add a new function xen_hvm_nopv_guest_late_init()
to detect PVH at a late time and panic itself if nopv enabled for a
PVH guest.

Signed-off-by: Zhenzhong Duan
Cc: Boris Ostrovsky
Cc: Juergen Gross
Cc: Stefano Stabellini
Cc: Thomas Gleixner
Cc: Ingo Molnar
Cc: Borislav Petkov
---
  arch/x86/xen/enlighten_hvm.c | 27 +++
  1 file changed, 27 insertions(+)

diff --git a/arch/x86/xen/enlighten_hvm.c b/arch/x86/xen/enlighten_hvm.c
index 1756cf7..09a010a 100644
--- a/arch/x86/xen/enlighten_hvm.c
+++ b/arch/x86/xen/enlighten_hvm.c
@@ -231,11 +231,37 @@ bool __init xen_hvm_need_lapic(void)
return true;
  }
  
+static __init void xen_hvm_nopv_guest_late_init(void)

+{
+#ifdef CONFIG_XEN_PVH
+   if (x86_platform.legacy.rtc || !x86_platform.legacy.no_vga)
+   return;
+
+   /* PVH detected. */
+   xen_pvh = true;
+
+   panic("\"nopv\" and \"xen_nopv\" parameters are unsupported in PVH 
guest.");
+#endif
+}

Can't all of this be done in xen_hvm_guest_late_init()? It has the same
tests already and it seems to me you should be able to panic from there.


Indeed, I didn't realize this, thanks for pointing, I'll fix it.

Zhenzhong


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Re: [Xen-devel] [PATCH v5 4/4] x86/xen: Add "nopv" support for HVM guest

2019-07-05 Thread Boris Ostrovsky
On 7/2/19 9:19 PM, Zhenzhong Duan wrote:
> PVH guest needs PV extentions to work, so "nopv" parameter should be
> ignored for PVH but not for HVM guest.
>
> If PVH guest boots up via the Xen-PVH boot entry, xen_pvh is set early,
> we know it's PVH guest and ignore "nopv" parameter directly.
>
> If PVH guest boots up via the normal boot entry same as HVM guest, it's
> hard to distinguish PVH and HVM guest at that time.
>
> To handle that case, add a new function xen_hvm_nopv_guest_late_init()
> to detect PVH at a late time and panic itself if nopv enabled for a
> PVH guest.
>
> Signed-off-by: Zhenzhong Duan 
> Cc: Boris Ostrovsky 
> Cc: Juergen Gross 
> Cc: Stefano Stabellini 
> Cc: Thomas Gleixner 
> Cc: Ingo Molnar 
> Cc: Borislav Petkov 
> ---
>  arch/x86/xen/enlighten_hvm.c | 27 +++
>  1 file changed, 27 insertions(+)
>
> diff --git a/arch/x86/xen/enlighten_hvm.c b/arch/x86/xen/enlighten_hvm.c
> index 1756cf7..09a010a 100644
> --- a/arch/x86/xen/enlighten_hvm.c
> +++ b/arch/x86/xen/enlighten_hvm.c
> @@ -231,11 +231,37 @@ bool __init xen_hvm_need_lapic(void)
>   return true;
>  }
>  
> +static __init void xen_hvm_nopv_guest_late_init(void)
> +{
> +#ifdef CONFIG_XEN_PVH
> + if (x86_platform.legacy.rtc || !x86_platform.legacy.no_vga)
> + return;
> +
> + /* PVH detected. */
> + xen_pvh = true;
> +
> + panic("\"nopv\" and \"xen_nopv\" parameters are unsupported in PVH 
> guest.");
> +#endif
> +}

Can't all of this be done in xen_hvm_guest_late_init()? It has the same
tests already and it seems to me you should be able to panic from there.


-boris


> +
> +
>  static uint32_t __init xen_platform_hvm(void)
>  {
>   if (xen_pv_domain())
>   return 0;
>  
> + if (xen_pvh_domain() && nopv) {
> + /* Guest booting via the Xen-PVH boot entry goes here */
> + pr_info("\"nopv\" parameter is ignored in PVH guest\n");
> + nopv = false;
> + } else if (nopv) {
> + /*
> +  * Guest booting via normal boot entry (like via grub2) goes
> +  * here.
> +  */
> + x86_init.hyper.guest_late_init = xen_hvm_nopv_guest_late_init;
> + return 0;
> + }
>   return xen_cpuid_base();
>  }
>  
> @@ -268,4 +294,5 @@ static __init void xen_hvm_guest_late_init(void)
>   .init.init_mem_mapping  = xen_hvm_init_mem_mapping,
>   .init.guest_late_init   = xen_hvm_guest_late_init,
>   .runtime.pin_vcpu   = xen_pin_vcpu,
> + .ignore_nopv= true,
>  };


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