diff mbox series

[XEN,v4,12/14] x86/ioreq: guard VIO_realmode_completion with CONFIG_VMX

Message ID e6e0f30ea69ecfed4d8de531fc42162162b3f6e5.1720501197.git.Sergiy_Kibrik@epam.com (mailing list archive)
State Superseded
Headers show
Series x86: make CPU virtualisation support configurable | expand

Commit Message

Sergiy Kibrik July 9, 2024, 6:09 a.m. UTC 
From: Xenia Ragiadakou <burzalodowa@gmail.com>

VIO_realmode_completion is specific to vmx realmode and thus the function
arch_vcpu_ioreq_completion() has actual handling code only in VMX-enabled build,
as for the rest x86 and ARM build configurations it is basically a stub.
So these stubs can be avoided by moving VIO_realmode_completion handler's code
under CONFIG_VMX and then ARM stub can be removed completely.

Signed-off-by: Xenia Ragiadakou <burzalodowa@gmail.com>
Signed-off-by: Sergiy Kibrik <Sergiy_Kibrik@epam.com>
CC: Julien Grall <julien@xen.org>
CC: Jan Beulich <jbeulich@suse.com>
---
changes in v4:
 - move whole arch_vcpu_ioreq_completion() under CONFIG_VMX and remove
   ARM's variant of this handler, as Julien suggested
changes in v1:
 - put VIO_realmode_completion enum under #ifdef CONFIG_VMX
---
 xen/arch/arm/ioreq.c                 | 6 ------
 xen/arch/x86/hvm/ioreq.c             | 2 ++
 xen/arch/x86/include/asm/hvm/ioreq.h | 5 +++++
 xen/common/ioreq.c                   | 5 ++++-
 xen/include/xen/ioreq.h              | 1 -
 5 files changed, 11 insertions(+), 8 deletions(-)

Comments

Jan Beulich July 9, 2024, 7:28 a.m. UTC | #1 
On 09.07.2024 08:09, Sergiy Kibrik wrote:
> --- a/xen/arch/x86/include/asm/hvm/ioreq.h
> +++ b/xen/arch/x86/include/asm/hvm/ioreq.h
> @@ -13,6 +13,11 @@
>  #define IOREQ_STATUS_UNHANDLED   X86EMUL_UNHANDLEABLE
>  #define IOREQ_STATUS_RETRY       X86EMUL_RETRY
>  
> +#ifdef CONFIG_VMX
> +bool arch_vcpu_ioreq_completion(enum vio_completion completion);
> +#define arch_vcpu_ioreq_completion
> +#endif

Putting the (or some kind of) #define here is certainly fine, but moving ...

> --- a/xen/include/xen/ioreq.h
> +++ b/xen/include/xen/ioreq.h
> @@ -111,7 +111,6 @@ void ioreq_domain_init(struct domain *d);
>  int ioreq_server_dm_op(struct xen_dm_op *op, struct domain *d, bool *const_op);
>  
>  bool arch_ioreq_complete_mmio(void);
> -bool arch_vcpu_ioreq_completion(enum vio_completion completion);
>  int arch_ioreq_server_map_pages(struct ioreq_server *s);
>  void arch_ioreq_server_unmap_pages(struct ioreq_server *s);
>  void arch_ioreq_server_enable(struct ioreq_server *s);

... the declaration from here requires that all architectures wanting to
implement the function need to have identical copies. That's unnecessary
risk of going out of sync.

As to the #define itself: It expanding to nothing means the call site
de-generates to

#ifdef arch_vcpu_ioreq_completion
        res = (completion);
#else

which hardly is what is meant (despite compiling fine, and it likely
only being Eclair which would then tell us about the issue). Further
there you're also removing a blank line, I don't see why you're doing
that.

Jan
Sergiy Kibrik July 10, 2024, 10:10 a.m. UTC | #2 
09.07.24 10:28, Jan Beulich:
> On 09.07.2024 08:09, Sergiy Kibrik wrote:
>> --- a/xen/arch/x86/include/asm/hvm/ioreq.h
>> +++ b/xen/arch/x86/include/asm/hvm/ioreq.h
>> @@ -13,6 +13,11 @@
>>   #define IOREQ_STATUS_UNHANDLED   X86EMUL_UNHANDLEABLE
>>   #define IOREQ_STATUS_RETRY       X86EMUL_RETRY
>>   
>> +#ifdef CONFIG_VMX
>> +bool arch_vcpu_ioreq_completion(enum vio_completion completion);
>> +#define arch_vcpu_ioreq_completion
>> +#endif
> 
> Putting the (or some kind of) #define here is certainly fine, but moving ...
> 
>> --- a/xen/include/xen/ioreq.h
>> +++ b/xen/include/xen/ioreq.h
>> @@ -111,7 +111,6 @@ void ioreq_domain_init(struct domain *d);
>>   int ioreq_server_dm_op(struct xen_dm_op *op, struct domain *d, bool *const_op);
>>   
>>   bool arch_ioreq_complete_mmio(void);
>> -bool arch_vcpu_ioreq_completion(enum vio_completion completion);
>>   int arch_ioreq_server_map_pages(struct ioreq_server *s);
>>   void arch_ioreq_server_unmap_pages(struct ioreq_server *s);
>>   void arch_ioreq_server_enable(struct ioreq_server *s);
> 
> ... the declaration from here requires that all architectures wanting to
> implement the function need to have identical copies. That's unnecessary
> risk of going out of sync.
> 
> As to the #define itself: It expanding to nothing means the call site
> de-generates to
> 
> #ifdef arch_vcpu_ioreq_completion
>          res = (completion);
> #else
> 
> which hardly is what is meant (despite compiling fine, and it likely
> only being Eclair which would then tell us about the issue). Further
> there you're also removing a blank line, I don't see why you're doing
> that.
> 

looking through these changes once again I wonder why can't we just move 
stub to the header like this:

in xen/include/xen/ioreq.h:

#ifdef arch_vcpu_ioreq_completion

#ifdef CONFIG_VMX
bool arch_vcpu_ioreq_completion(enum vio_completion completion);
#else
static inline bool arch_vcpu_ioreq_completion(enum vio_completion 
completion)
{
     ASSERT_UNREACHABLE();
     return true;
}
#endif


and avoid additional pre-processor variables & conditionals, because it 
looks like we do need some kind of stub that does ASSERT_UNREACHABLE() 
anyway.

   -Sergiy
Jan Beulich July 10, 2024, 10:19 a.m. UTC | #3 
On 10.07.2024 12:10, Sergiy Kibrik wrote:
> 09.07.24 10:28, Jan Beulich:
>> On 09.07.2024 08:09, Sergiy Kibrik wrote:
>>> --- a/xen/arch/x86/include/asm/hvm/ioreq.h
>>> +++ b/xen/arch/x86/include/asm/hvm/ioreq.h
>>> @@ -13,6 +13,11 @@
>>>   #define IOREQ_STATUS_UNHANDLED   X86EMUL_UNHANDLEABLE
>>>   #define IOREQ_STATUS_RETRY       X86EMUL_RETRY
>>>   
>>> +#ifdef CONFIG_VMX
>>> +bool arch_vcpu_ioreq_completion(enum vio_completion completion);
>>> +#define arch_vcpu_ioreq_completion
>>> +#endif
>>
>> Putting the (or some kind of) #define here is certainly fine, but moving ...
>>
>>> --- a/xen/include/xen/ioreq.h
>>> +++ b/xen/include/xen/ioreq.h
>>> @@ -111,7 +111,6 @@ void ioreq_domain_init(struct domain *d);
>>>   int ioreq_server_dm_op(struct xen_dm_op *op, struct domain *d, bool *const_op);
>>>   
>>>   bool arch_ioreq_complete_mmio(void);
>>> -bool arch_vcpu_ioreq_completion(enum vio_completion completion);
>>>   int arch_ioreq_server_map_pages(struct ioreq_server *s);
>>>   void arch_ioreq_server_unmap_pages(struct ioreq_server *s);
>>>   void arch_ioreq_server_enable(struct ioreq_server *s);
>>
>> ... the declaration from here requires that all architectures wanting to
>> implement the function need to have identical copies. That's unnecessary
>> risk of going out of sync.
>>
>> As to the #define itself: It expanding to nothing means the call site
>> de-generates to
>>
>> #ifdef arch_vcpu_ioreq_completion
>>          res = (completion);
>> #else
>>
>> which hardly is what is meant (despite compiling fine, and it likely
>> only being Eclair which would then tell us about the issue). Further
>> there you're also removing a blank line, I don't see why you're doing
>> that.
>>
> 
> looking through these changes once again I wonder why can't we just move 
> stub to the header like this:
> 
> in xen/include/xen/ioreq.h:
> 
> #ifdef arch_vcpu_ioreq_completion
> 
> #ifdef CONFIG_VMX
> bool arch_vcpu_ioreq_completion(enum vio_completion completion);
> #else
> static inline bool arch_vcpu_ioreq_completion(enum vio_completion 
> completion)
> {
>      ASSERT_UNREACHABLE();
>      return true;
> }
> #endif
> 
> 
> and avoid additional pre-processor variables & conditionals, because it 
> looks like we do need some kind of stub that does ASSERT_UNREACHABLE() 
> anyway.

That's possible to do, yes, but not as long as you key it off of CONFIG_VMX.
This arch-specific setting would better not be used in a common code header.
You could introduce a helper CONFIG_* which VMX selects, at which point
doing what you suggest is an option.

However, in what you have above I can't figure why "#ifdef
arch_vcpu_ioreq_completion" is still there.

Jan
Sergiy Kibrik July 12, 2024, 8:03 a.m. UTC | #4 
10.07.24 13:19, Jan Beulich:
>> looking through these changes once again I wonder why can't we just move
>> stub to the header like this:
>>
>> in xen/include/xen/ioreq.h:
>>
>> #ifdef arch_vcpu_ioreq_completion
>>
>> #ifdef CONFIG_VMX
>> bool arch_vcpu_ioreq_completion(enum vio_completion completion);
>> #else
>> static inline bool arch_vcpu_ioreq_completion(enum vio_completion
>> completion)
>> {
>>       ASSERT_UNREACHABLE();
>>       return true;
>> }
>> #endif
>>
>>
>> and avoid additional pre-processor variables & conditionals, because it
>> looks like we do need some kind of stub that does ASSERT_UNREACHABLE()
>> anyway.
> That's possible to do, yes, but not as long as you key it off of CONFIG_VMX.
> This arch-specific setting would better not be used in a common code header.
> You could introduce a helper CONFIG_* which VMX selects, at which point
> doing what you suggest is an option.
> 

ok, I'll try this option in next series, lets see how it will look

> However, in what you have above I can't figure why "#ifdef
> arch_vcpu_ioreq_completion" is still there.
> 

disregard it please, a copy-paste error

   -Sergiy
diff mbox series

Patch

diff --git a/xen/arch/arm/ioreq.c b/xen/arch/arm/ioreq.c
index 5df755b48b..2e829d2e7f 100644
--- a/xen/arch/arm/ioreq.c
+++ b/xen/arch/arm/ioreq.c
@@ -135,12 +135,6 @@  bool arch_ioreq_complete_mmio(void)
     return false;
 }
 
-bool arch_vcpu_ioreq_completion(enum vio_completion completion)
-{
-    ASSERT_UNREACHABLE();
-    return true;
-}
-
 /*
  * The "legacy" mechanism of mapping magic pages for the IOREQ servers
  * is x86 specific, so the following hooks don't need to be implemented on Arm:
diff --git a/xen/arch/x86/hvm/ioreq.c b/xen/arch/x86/hvm/ioreq.c
index 4eb7a70182..0406630dc8 100644
--- a/xen/arch/x86/hvm/ioreq.c
+++ b/xen/arch/x86/hvm/ioreq.c
@@ -29,6 +29,7 @@  bool arch_ioreq_complete_mmio(void)
     return handle_mmio();
 }
 
+#ifdef CONFIG_VMX
 bool arch_vcpu_ioreq_completion(enum vio_completion completion)
 {
     switch ( completion )
@@ -51,6 +52,7 @@  bool arch_vcpu_ioreq_completion(enum vio_completion completion)
 
     return true;
 }
+#endif
 
 static gfn_t hvm_alloc_legacy_ioreq_gfn(struct ioreq_server *s)
 {
diff --git a/xen/arch/x86/include/asm/hvm/ioreq.h b/xen/arch/x86/include/asm/hvm/ioreq.h
index 84be14fd08..c5f16a1e4a 100644
--- a/xen/arch/x86/include/asm/hvm/ioreq.h
+++ b/xen/arch/x86/include/asm/hvm/ioreq.h
@@ -13,6 +13,11 @@ 
 #define IOREQ_STATUS_UNHANDLED   X86EMUL_UNHANDLEABLE
 #define IOREQ_STATUS_RETRY       X86EMUL_RETRY
 
+#ifdef CONFIG_VMX
+bool arch_vcpu_ioreq_completion(enum vio_completion completion);
+#define arch_vcpu_ioreq_completion
+#endif
+
 #endif /* __ASM_X86_HVM_IOREQ_H__ */
 
 /*
diff --git a/xen/common/ioreq.c b/xen/common/ioreq.c
index 1257a3d972..10fe932a7e 100644
--- a/xen/common/ioreq.c
+++ b/xen/common/ioreq.c
@@ -242,9 +242,12 @@  bool vcpu_ioreq_handle_completion(struct vcpu *v)
         res = handle_pio(vio->req.addr, vio->req.size,
                          vio->req.dir);
         break;
-
     default:
+#ifdef arch_vcpu_ioreq_completion
         res = arch_vcpu_ioreq_completion(completion);
+#else
+        ASSERT_UNREACHABLE();
+#endif
         break;
     }
 
diff --git a/xen/include/xen/ioreq.h b/xen/include/xen/ioreq.h
index cd399adf17..22fb9ba7b0 100644
--- a/xen/include/xen/ioreq.h
+++ b/xen/include/xen/ioreq.h
@@ -111,7 +111,6 @@  void ioreq_domain_init(struct domain *d);
 int ioreq_server_dm_op(struct xen_dm_op *op, struct domain *d, bool *const_op);
 
 bool arch_ioreq_complete_mmio(void);
-bool arch_vcpu_ioreq_completion(enum vio_completion completion);
 int arch_ioreq_server_map_pages(struct ioreq_server *s);
 void arch_ioreq_server_unmap_pages(struct ioreq_server *s);
 void arch_ioreq_server_enable(struct ioreq_server *s);