[Xen-devel] [PATCH] xen/public: arch-arm: Restrict the visibility of struct vcpu_guest_core_regs

Julien Grall posted 1 patch 4 years, 11 months ago
Patches applied successfully (tree, apply log)
git fetch https://github.com/patchew-project/xen tags/patchew/20190520181250.17404-1-julien.grall@arm.com
There is a newer version of this series
xen/include/public/arch-arm.h | 3 +++
1 file changed, 3 insertions(+)
[Xen-devel] [PATCH] xen/public: arch-arm: Restrict the visibility of struct vcpu_guest_core_regs
Posted by Julien Grall 4 years, 11 months ago
Currently, the structure vcpu_guest_core_regs is part of the public API.
This implies that any change in the structure should be backward
compatible.

However, the structure is only needed by the tools and Xen. It is also
not expected to be ever used outside of that context. So we could save us
some headache by only declaring the structure for Xen and tools.

Suggested-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Julien Grall <julien.grall@arm.com>

---
    This is a follow-up of the discussion [1].

    As this is now Xen and tools only, I am wondering whether the check on
    GNU_C is still necessary. I am happy to send a follow-up patch (or fold
    in this one) if it can be removed.

    [1] <3c245c5b-51c6-1d0e-ad6c-42414573166f@arm.com>
---
 xen/include/public/arch-arm.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/xen/include/public/arch-arm.h b/xen/include/public/arch-arm.h
index eb424e8286..e9a86d8eb8 100644
--- a/xen/include/public/arch-arm.h
+++ b/xen/include/public/arch-arm.h
@@ -197,6 +197,7 @@
     } while ( 0 )
 #define set_xen_guest_handle(hnd, val) set_xen_guest_handle_raw(hnd, val)
 
+#if defined(__XEN__) || defined(__XEN_TOOLS__)
 #if defined(__GNUC__) && !defined(__STRICT_ANSI__)
 /* Anonymous union includes both 32- and 64-bit names (e.g., r0/x0). */
 # define __DECL_REG(n64, n32) union {          \
@@ -272,6 +273,8 @@ DEFINE_XEN_GUEST_HANDLE(vcpu_guest_core_regs_t);
 
 #undef __DECL_REG
 
+#endif
+
 typedef uint64_t xen_pfn_t;
 #define PRI_xen_pfn PRIx64
 #define PRIu_xen_pfn PRIu64
-- 
2.11.0


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Re: [Xen-devel] [PATCH] xen/public: arch-arm: Restrict the visibility of struct vcpu_guest_core_regs
Posted by Jan Beulich 4 years, 11 months ago
>>> On 20.05.19 at 20:12, <julien.grall@arm.com> wrote:
>     As this is now Xen and tools only, I am wondering whether the check on
>     GNU_C is still necessary. I am happy to send a follow-up patch (or fold
>     in this one) if it can be removed.

I think this should be dropped if it can be without breaking any
part of the build.

> --- a/xen/include/public/arch-arm.h
> +++ b/xen/include/public/arch-arm.h
> @@ -197,6 +197,7 @@
>      } while ( 0 )
>  #define set_xen_guest_handle(hnd, val) set_xen_guest_handle_raw(hnd, val)
>  
> +#if defined(__XEN__) || defined(__XEN_TOOLS__)
>  #if defined(__GNUC__) && !defined(__STRICT_ANSI__)
>  /* Anonymous union includes both 32- and 64-bit names (e.g., r0/x0). */
>  # define __DECL_REG(n64, n32) union {          \
> @@ -272,6 +273,8 @@ DEFINE_XEN_GUEST_HANDLE(vcpu_guest_core_regs_t);
>  
>  #undef __DECL_REG
>  
> +#endif

If I was the maintainer of this code, I'd ask for the struct declaration
to be moved (into the existing #if) rather than adding a 2nd #if.

Jan



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Re: [Xen-devel] [PATCH] xen/public: arch-arm: Restrict the visibility of struct vcpu_guest_core_regs
Posted by Julien Grall 4 years, 11 months ago
Hi Jan,

On 5/21/19 10:26 AM, Jan Beulich wrote:
>>>> On 20.05.19 at 20:12, <julien.grall@arm.com> wrote:
>>      As this is now Xen and tools only, I am wondering whether the check on
>>      GNU_C is still necessary. I am happy to send a follow-up patch (or fold
>>      in this one) if it can be removed.
> 
> I think this should be dropped if it can be without breaking any
> part of the build.
This is because all the tools are part of xen.git, right?

>> --- a/xen/include/public/arch-arm.h
>> +++ b/xen/include/public/arch-arm.h
>> @@ -197,6 +197,7 @@
>>       } while ( 0 )
>>   #define set_xen_guest_handle(hnd, val) set_xen_guest_handle_raw(hnd, val)
>>   
>> +#if defined(__XEN__) || defined(__XEN_TOOLS__)
>>   #if defined(__GNUC__) && !defined(__STRICT_ANSI__)
>>   /* Anonymous union includes both 32- and 64-bit names (e.g., r0/x0). */
>>   # define __DECL_REG(n64, n32) union {          \
>> @@ -272,6 +273,8 @@ DEFINE_XEN_GUEST_HANDLE(vcpu_guest_core_regs_t);
>>   
>>   #undef __DECL_REG
>>   
>> +#endif
> 
> If I was the maintainer of this code, I'd ask for the struct declaration
> to be moved (into the existing #if) rather than adding a 2nd #if.

s/2nd/3rd/ ;)

The reason I haven't done that is git will generate a completely 
unrelated diff. So it makes quite difficult to understand the purpose of 
the patch.

Cheers,

-- 
Julien Grall

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Re: [Xen-devel] [PATCH] xen/public: arch-arm: Restrict the visibility of struct vcpu_guest_core_regs
Posted by Jan Beulich 4 years, 11 months ago
>>> On 21.05.19 at 11:35, <julien.grall@arm.com> wrote:
> On 5/21/19 10:26 AM, Jan Beulich wrote:
>>>>> On 20.05.19 at 20:12, <julien.grall@arm.com> wrote:
>>>      As this is now Xen and tools only, I am wondering whether the check on
>>>      GNU_C is still necessary. I am happy to send a follow-up patch (or fold
>>>      in this one) if it can be removed.
>> 
>> I think this should be dropped if it can be without breaking any
>> part of the build.
> This is because all the tools are part of xen.git, right?

Right - no-one else is supposed to define __XEN_TOOLS__, or
if anyone does, they're on their own.

>>> --- a/xen/include/public/arch-arm.h
>>> +++ b/xen/include/public/arch-arm.h
>>> @@ -197,6 +197,7 @@
>>>       } while ( 0 )
>>>   #define set_xen_guest_handle(hnd, val) set_xen_guest_handle_raw(hnd, val)
>>>   
>>> +#if defined(__XEN__) || defined(__XEN_TOOLS__)
>>>   #if defined(__GNUC__) && !defined(__STRICT_ANSI__)
>>>   /* Anonymous union includes both 32- and 64-bit names (e.g., r0/x0). */
>>>   # define __DECL_REG(n64, n32) union {          \
>>> @@ -272,6 +273,8 @@ DEFINE_XEN_GUEST_HANDLE(vcpu_guest_core_regs_t);
>>>   
>>>   #undef __DECL_REG
>>>   
>>> +#endif
>> 
>> If I was the maintainer of this code, I'd ask for the struct declaration
>> to be moved (into the existing #if) rather than adding a 2nd #if.
> 
> s/2nd/3rd/ ;)
> 
> The reason I haven't done that is git will generate a completely 
> unrelated diff. So it makes quite difficult to understand the purpose of 
> the patch.

Well, as said - you're the maintainer. I wouldn't be bothered overly
much by a strange diff that might result.

Jan



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Re: [Xen-devel] [PATCH] xen/public: arch-arm: Restrict the visibility of struct vcpu_guest_core_regs
Posted by Julien Grall 4 years, 11 months ago
Hi Jan,

On 5/21/19 10:43 AM, Jan Beulich wrote:
>>>> On 21.05.19 at 11:35, <julien.grall@arm.com> wrote:
>> On 5/21/19 10:26 AM, Jan Beulich wrote:
>>>>>> On 20.05.19 at 20:12, <julien.grall@arm.com> wrote:
>>>>       As this is now Xen and tools only, I am wondering whether the check on
>>>>       GNU_C is still necessary. I am happy to send a follow-up patch (or fold
>>>>       in this one) if it can be removed.
>>>
>>> I think this should be dropped if it can be without breaking any
>>> part of the build.
>> This is because all the tools are part of xen.git, right?
> 
> Right - no-one else is supposed to define __XEN_TOOLS__, or
> if anyone does, they're on their own.

Thanks for the information. I will do a full build check.

> 
>>>> --- a/xen/include/public/arch-arm.h
>>>> +++ b/xen/include/public/arch-arm.h
>>>> @@ -197,6 +197,7 @@
>>>>        } while ( 0 )
>>>>    #define set_xen_guest_handle(hnd, val) set_xen_guest_handle_raw(hnd, val)
>>>>    
>>>> +#if defined(__XEN__) || defined(__XEN_TOOLS__)
>>>>    #if defined(__GNUC__) && !defined(__STRICT_ANSI__)
>>>>    /* Anonymous union includes both 32- and 64-bit names (e.g., r0/x0). */
>>>>    # define __DECL_REG(n64, n32) union {          \
>>>> @@ -272,6 +273,8 @@ DEFINE_XEN_GUEST_HANDLE(vcpu_guest_core_regs_t);
>>>>    
>>>>    #undef __DECL_REG
>>>>    
>>>> +#endif
>>>
>>> If I was the maintainer of this code, I'd ask for the struct declaration
>>> to be moved (into the existing #if) rather than adding a 2nd #if.
>>
>> s/2nd/3rd/ ;)
>>
>> The reason I haven't done that is git will generate a completely
>> unrelated diff. So it makes quite difficult to understand the purpose of
>> the patch.
> 
> Well, as said - you're the maintainer. I wouldn't be bothered overly
> much by a strange diff that might result.

I will wait on Stefano's input.


Cheers,

-- 
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Re: [Xen-devel] [PATCH] xen/public: arch-arm: Restrict the visibility of struct vcpu_guest_core_regs
Posted by Stefano Stabellini 4 years, 11 months ago
On Tue, 21 May 2019, Julien Grall wrote:
> Hi Jan,
> 
> On 5/21/19 10:43 AM, Jan Beulich wrote:
> > > > > On 21.05.19 at 11:35, <julien.grall@arm.com> wrote:
> > > On 5/21/19 10:26 AM, Jan Beulich wrote:
> > > > > > > On 20.05.19 at 20:12, <julien.grall@arm.com> wrote:
> > > > >       As this is now Xen and tools only, I am wondering whether the
> > > > > check on
> > > > >       GNU_C is still necessary. I am happy to send a follow-up patch
> > > > > (or fold
> > > > >       in this one) if it can be removed.
> > > > 
> > > > I think this should be dropped if it can be without breaking any
> > > > part of the build.
> > > This is because all the tools are part of xen.git, right?
> > 
> > Right - no-one else is supposed to define __XEN_TOOLS__, or
> > if anyone does, they're on their own.
> 
> Thanks for the information. I will do a full build check.
> 
> > 
> > > > > --- a/xen/include/public/arch-arm.h
> > > > > +++ b/xen/include/public/arch-arm.h
> > > > > @@ -197,6 +197,7 @@
> > > > >        } while ( 0 )
> > > > >    #define set_xen_guest_handle(hnd, val)
> > > > > set_xen_guest_handle_raw(hnd, val)
> > > > >    +#if defined(__XEN__) || defined(__XEN_TOOLS__)
> > > > >    #if defined(__GNUC__) && !defined(__STRICT_ANSI__)
> > > > >    /* Anonymous union includes both 32- and 64-bit names (e.g.,
> > > > > r0/x0). */
> > > > >    # define __DECL_REG(n64, n32) union {          \
> > > > > @@ -272,6 +273,8 @@ DEFINE_XEN_GUEST_HANDLE(vcpu_guest_core_regs_t);
> > > > >       #undef __DECL_REG
> > > > >    +#endif
> > > > 
> > > > If I was the maintainer of this code, I'd ask for the struct declaration
> > > > to be moved (into the existing #if) rather than adding a 2nd #if.
> > > 
> > > s/2nd/3rd/ ;)
> > > 
> > > The reason I haven't done that is git will generate a completely
> > > unrelated diff. So it makes quite difficult to understand the purpose of
> > > the patch.
> > 
> > Well, as said - you're the maintainer. I wouldn't be bothered overly
> > much by a strange diff that might result.
> 
> I will wait on Stefano's input.

Yes, please follow Jan's advice, thanks.

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Re: [Xen-devel] [PATCH] xen/public: arch-arm: Restrict the visibility of struct vcpu_guest_core_regs
Posted by Julien Grall 4 years, 11 months ago

On 21/05/2019 10:55, Julien Grall wrote:
> Hi Jan,
> 
> On 5/21/19 10:43 AM, Jan Beulich wrote:
>>>>> On 21.05.19 at 11:35, <julien.grall@arm.com> wrote:
>>> On 5/21/19 10:26 AM, Jan Beulich wrote:
>>>>>>> On 20.05.19 at 20:12, <julien.grall@arm.com> wrote:
>>>>>       As this is now Xen and tools only, I am wondering whether the check on
>>>>>       GNU_C is still necessary. I am happy to send a follow-up patch (or fold
>>>>>       in this one) if it can be removed.
>>>>
>>>> I think this should be dropped if it can be without breaking any
>>>> part of the build.
>>> This is because all the tools are part of xen.git, right?
>>
>> Right - no-one else is supposed to define __XEN_TOOLS__, or
>> if anyone does, they're on their own.
> 
> Thanks for the information. I will do a full build check.

I thought about this again, long term there are an attempt to build xen with 
other compiler not necessarily supporting GNU C extension.

While this would probably not be the only place that need to be reworked, we 
would have to revert part of this change. So I will not drop the #ifdef here.

I will resend the patch next week to give some time for more feedback.


Cheers,

-- 
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Re: [Xen-devel] [PATCH] xen/public: arch-arm: Restrict the visibility of struct vcpu_guest_core_regs
Posted by Jan Beulich 4 years, 11 months ago
>>> On 22.05.19 at 14:20, <julien.grall@arm.com> wrote:

> 
> On 21/05/2019 10:55, Julien Grall wrote:
>> Hi Jan,
>> 
>> On 5/21/19 10:43 AM, Jan Beulich wrote:
>>>>>> On 21.05.19 at 11:35, <julien.grall@arm.com> wrote:
>>>> On 5/21/19 10:26 AM, Jan Beulich wrote:
>>>>>>>> On 20.05.19 at 20:12, <julien.grall@arm.com> wrote:
>>>>>>       As this is now Xen and tools only, I am wondering whether the check on
>>>>>>       GNU_C is still necessary. I am happy to send a follow-up patch (or fold
>>>>>>       in this one) if it can be removed.
>>>>>
>>>>> I think this should be dropped if it can be without breaking any
>>>>> part of the build.
>>>> This is because all the tools are part of xen.git, right?
>>>
>>> Right - no-one else is supposed to define __XEN_TOOLS__, or
>>> if anyone does, they're on their own.
>> 
>> Thanks for the information. I will do a full build check.
> 
> I thought about this again, long term there are an attempt to build xen with 
> other compiler not necessarily supporting GNU C extension.
> While this would probably not be the only place that need to be reworked, we 
> would have to revert part of this change. So I will not drop the #ifdef here.

Well, I don't know how it is for Arm, but on x86 we actually use the
"extended" naming quite extensively, so building with a compiler
that doesn't support this extension is not really an option there.

Jan



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Re: [Xen-devel] [PATCH] xen/public: arch-arm: Restrict the visibility of struct vcpu_guest_core_regs
Posted by Julien Grall 4 years, 11 months ago
(+Artem)

Hi Jan,

On 22/05/2019 13:29, Jan Beulich wrote:
>>>> On 22.05.19 at 14:20, <julien.grall@arm.com> wrote:
> 
>>
>> On 21/05/2019 10:55, Julien Grall wrote:
>>> Hi Jan,
>>>
>>> On 5/21/19 10:43 AM, Jan Beulich wrote:
>>>>>>> On 21.05.19 at 11:35, <julien.grall@arm.com> wrote:
>>>>> On 5/21/19 10:26 AM, Jan Beulich wrote:
>>>>>>>>> On 20.05.19 at 20:12, <julien.grall@arm.com> wrote:
>>>>>>>        As this is now Xen and tools only, I am wondering whether the check on
>>>>>>>        GNU_C is still necessary. I am happy to send a follow-up patch (or fold
>>>>>>>        in this one) if it can be removed.
>>>>>>
>>>>>> I think this should be dropped if it can be without breaking any
>>>>>> part of the build.
>>>>> This is because all the tools are part of xen.git, right?
>>>>
>>>> Right - no-one else is supposed to define __XEN_TOOLS__, or
>>>> if anyone does, they're on their own.
>>>
>>> Thanks for the information. I will do a full build check.
>>
>> I thought about this again, long term there are an attempt to build xen with
>> other compiler not necessarily supporting GNU C extension.
>> While this would probably not be the only place that need to be reworked, we
>> would have to revert part of this change. So I will not drop the #ifdef here.
> 
> Well, I don't know how it is for Arm, but on x86 we actually use the
> "extended" naming quite extensively, so building with a compiler
> that doesn't support this extension is not really an option there.

For the Arm, I think only cpu_user_regs is using "extended" naming. It should be 
possible to remove it without too much trouble here.

@Artem, is there any restriction to use anonymous union in functional safety?

Cheers,

-- 
Julien Grall

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