[v1] Port Xen to Hyper-V

[Xen-devel] [PATCH for-next RFC 6/8] x86: make probe_xen return boolean value

Posted by Wei Liu 6 years, 1 month ago

We need indication whether it has succeeded or not.

Signed-off-by: Wei Liu <liuwe@microsoft.com>
---
 xen/arch/x86/guest/hypervisor.c | 5 ++++-
 xen/arch/x86/guest/xen/xen.c    | 7 ++++---
 xen/include/asm-x86/guest/xen.h | 4 ++--
 3 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/xen/arch/x86/guest/hypervisor.c b/xen/arch/x86/guest/hypervisor.c
index b0a724bf13..fb572b0402 100644
--- a/xen/arch/x86/guest/hypervisor.c
+++ b/xen/arch/x86/guest/hypervisor.c
@@ -34,7 +34,10 @@ void __init probe_hypervisor(void)
     if ( !(cpuid_ecx(1) & cpufeat_mask(X86_FEATURE_HYPERVISOR)) )
         return;
 
-    probe_xen();
+    if ( probe_xen() )
+        return;
+
+    /* Hyper-V probing to follow. */
 }
 
 static void __init init_memmap(void)
diff --git a/xen/arch/x86/guest/xen/xen.c b/xen/arch/x86/guest/xen/xen.c
index a730e6ad1b..8390b045f0 100644
--- a/xen/arch/x86/guest/xen/xen.c
+++ b/xen/arch/x86/guest/xen/xen.c
@@ -66,20 +66,21 @@ static void __init find_xen_leaves(void)
     }
 }
 
-void __init probe_xen(void)
+bool __init probe_xen(void)
 {
     if ( xen_guest )
-        return;
+        return true;
 
     find_xen_leaves();
 
     if ( !xen_cpuid_base )
-        return;
+        return false;
 
     /* Fill the hypercall page. */
     wrmsrl(cpuid_ebx(xen_cpuid_base + 2), __pa(hypercall_page));
 
     xen_guest = true;
+    return true;
 }
 
 static void map_shared_info(void)
diff --git a/xen/include/asm-x86/guest/xen.h b/xen/include/asm-x86/guest/xen.h
index d031f1f70d..7eda3d4956 100644
--- a/xen/include/asm-x86/guest/xen.h
+++ b/xen/include/asm-x86/guest/xen.h
@@ -32,7 +32,7 @@ extern bool xen_guest;
 extern bool pv_console;
 extern uint32_t xen_cpuid_base;
 
-void probe_xen(void);
+bool probe_xen(void);
 void xen_setup(void);
 void xen_ap_setup(void);
 void xen_resume(void);
@@ -45,7 +45,7 @@ DECLARE_PER_CPU(struct vcpu_info *, vcpu_info);
 #define xen_guest 0
 #define pv_console 0
 
-static inline void probe_xen(void) {}
+static inline bool probe_xen(void) { return false; }
 
 #endif /* CONFIG_XEN_GUEST */
 #endif /* __X86_GUEST_XEN_H__ */
-- 
2.20.1


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Re: [Xen-devel] [PATCH for-next RFC 6/8] x86: make probe_xen return boolean value

Posted by Roger Pau Monné 6 years, 1 month ago

On Mon, Sep 23, 2019 at 11:09:29AM +0100, Wei Liu wrote:
> We need indication whether it has succeeded or not.
> 
> Signed-off-by: Wei Liu <liuwe@microsoft.com>

The code LGTM, I have just a suggestion on the approach.

> ---
>  xen/arch/x86/guest/hypervisor.c | 5 ++++-
>  xen/arch/x86/guest/xen/xen.c    | 7 ++++---
>  xen/include/asm-x86/guest/xen.h | 4 ++--
>  3 files changed, 10 insertions(+), 6 deletions(-)
> 
> diff --git a/xen/arch/x86/guest/hypervisor.c b/xen/arch/x86/guest/hypervisor.c
> index b0a724bf13..fb572b0402 100644
> --- a/xen/arch/x86/guest/hypervisor.c
> +++ b/xen/arch/x86/guest/hypervisor.c
> @@ -34,7 +34,10 @@ void __init probe_hypervisor(void)
>      if ( !(cpuid_ecx(1) & cpufeat_mask(X86_FEATURE_HYPERVISOR)) )
>          return;
>  
> -    probe_xen();
> +    if ( probe_xen() )
> +        return;
> +
> +    /* Hyper-V probing to follow. */

Instead of having to append a new probe_foo here every time support for
running on a new hypervisor is added, you could do something similar
to what's done in REGISTER_VPCI_INIT, where each hypervisor would
register it's own set of helpers and probe function in a specific
section, and then you would just iterate over all the guest support
that's compiled in Xen.

That would also prevent you from having to export a dummy probe_xen
helper if CONFIG_XEN_GUEST is not defined.

Anyway, maybe that's overkill...

Thanks, Roger.

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Re: [Xen-devel] [PATCH for-next RFC 6/8] x86: make probe_xen return boolean value

Posted by Wei Liu 6 years, 1 month ago

On Wed, Sep 25, 2019 at 12:44:27PM +0200, Roger Pau Monné wrote:
> On Mon, Sep 23, 2019 at 11:09:29AM +0100, Wei Liu wrote:
> > We need indication whether it has succeeded or not.
> > 
> > Signed-off-by: Wei Liu <liuwe@microsoft.com>
> 
> The code LGTM, I have just a suggestion on the approach.
> 
> > ---
> >  xen/arch/x86/guest/hypervisor.c | 5 ++++-
> >  xen/arch/x86/guest/xen/xen.c    | 7 ++++---
> >  xen/include/asm-x86/guest/xen.h | 4 ++--
> >  3 files changed, 10 insertions(+), 6 deletions(-)
> > 
> > diff --git a/xen/arch/x86/guest/hypervisor.c b/xen/arch/x86/guest/hypervisor.c
> > index b0a724bf13..fb572b0402 100644
> > --- a/xen/arch/x86/guest/hypervisor.c
> > +++ b/xen/arch/x86/guest/hypervisor.c
> > @@ -34,7 +34,10 @@ void __init probe_hypervisor(void)
> >      if ( !(cpuid_ecx(1) & cpufeat_mask(X86_FEATURE_HYPERVISOR)) )
> >          return;
> >  
> > -    probe_xen();
> > +    if ( probe_xen() )
> > +        return;
> > +
> > +    /* Hyper-V probing to follow. */
> 
> Instead of having to append a new probe_foo here every time support for
> running on a new hypervisor is added, you could do something similar
> to what's done in REGISTER_VPCI_INIT, where each hypervisor would
> register it's own set of helpers and probe function in a specific
> section, and then you would just iterate over all the guest support
> that's compiled in Xen.
> 
> That would also prevent you from having to export a dummy probe_xen
> helper if CONFIG_XEN_GUEST is not defined.
> 
> Anyway, maybe that's overkill...

Let's see what Andrew and Jan think.

Either works for me -- it is just a matter of writing code, but
obviously the less work the better. :-)

Wei.

> 
> Thanks, Roger.

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