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Re: [XEN PATCH 3/6] AMD/IOMMU: address violations of MISRA C:2012 Rule 8.2


  • To: Stefano Stabellini <sstabellini@xxxxxxxxxx>, Federico Serafini <federico.serafini@xxxxxxxxxxx>
  • From: Jan Beulich <jbeulich@xxxxxxxx>
  • Date: Wed, 6 Dec 2023 09:16:56 +0100
  • Autocrypt: addr=jbeulich@xxxxxxxx; keydata= xsDiBFk3nEQRBADAEaSw6zC/EJkiwGPXbWtPxl2xCdSoeepS07jW8UgcHNurfHvUzogEq5xk hu507c3BarVjyWCJOylMNR98Yd8VqD9UfmX0Hb8/BrA+Hl6/DB/eqGptrf4BSRwcZQM32aZK 7Pj2XbGWIUrZrd70x1eAP9QE3P79Y2oLrsCgbZJfEwCgvz9JjGmQqQkRiTVzlZVCJYcyGGsD /0tbFCzD2h20ahe8rC1gbb3K3qk+LpBtvjBu1RY9drYk0NymiGbJWZgab6t1jM7sk2vuf0Py O9Hf9XBmK0uE9IgMaiCpc32XV9oASz6UJebwkX+zF2jG5I1BfnO9g7KlotcA/v5ClMjgo6Gl MDY4HxoSRu3i1cqqSDtVlt+AOVBJBACrZcnHAUSuCXBPy0jOlBhxPqRWv6ND4c9PH1xjQ3NP nxJuMBS8rnNg22uyfAgmBKNLpLgAGVRMZGaGoJObGf72s6TeIqKJo/LtggAS9qAUiuKVnygo 3wjfkS9A3DRO+SpU7JqWdsveeIQyeyEJ/8PTowmSQLakF+3fote9ybzd880fSmFuIEJldWxp Y2ggPGpiZXVsaWNoQHN1c2UuY29tPsJgBBMRAgAgBQJZN5xEAhsDBgsJCAcDAgQVAggDBBYC AwECHgECF4AACgkQoDSui/t3IH4J+wCfQ5jHdEjCRHj23O/5ttg9r9OIruwAn3103WUITZee e7Sbg12UgcQ5lv7SzsFNBFk3nEQQCACCuTjCjFOUdi5Nm244F+78kLghRcin/awv+IrTcIWF hUpSs1Y91iQQ7KItirz5uwCPlwejSJDQJLIS+QtJHaXDXeV6NI0Uef1hP20+y8qydDiVkv6l IreXjTb7DvksRgJNvCkWtYnlS3mYvQ9NzS9PhyALWbXnH6sIJd2O9lKS1Mrfq+y0IXCP10eS FFGg+Av3IQeFatkJAyju0PPthyTqxSI4lZYuJVPknzgaeuJv/2NccrPvmeDg6Coe7ZIeQ8Yj t0ARxu2xytAkkLCel1Lz1WLmwLstV30g80nkgZf/wr+/BXJW/oIvRlonUkxv+IbBM3dX2OV8 AmRv1ySWPTP7AAMFB/9PQK/VtlNUJvg8GXj9ootzrteGfVZVVT4XBJkfwBcpC/XcPzldjv+3 HYudvpdNK3lLujXeA5fLOH+Z/G9WBc5pFVSMocI71I8bT8lIAzreg0WvkWg5V2WZsUMlnDL9 mpwIGFhlbM3gfDMs7MPMu8YQRFVdUvtSpaAs8OFfGQ0ia3LGZcjA6Ik2+xcqscEJzNH+qh8V m5jjp28yZgaqTaRbg3M/+MTbMpicpZuqF4rnB0AQD12/3BNWDR6bmh+EkYSMcEIpQmBM51qM EKYTQGybRCjpnKHGOxG0rfFY1085mBDZCH5Kx0cl0HVJuQKC+dV2ZY5AqjcKwAxpE75MLFkr wkkEGBECAAkFAlk3nEQCGwwACgkQoDSui/t3IH7nnwCfcJWUDUFKdCsBH/E5d+0ZnMQi+G0A nAuWpQkjM1ASeQwSHEeAWPgskBQL
  • Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx, consulting@xxxxxxxxxxx, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
  • Delivery-date: Wed, 06 Dec 2023 08:17:15 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xenproject.org>

On 06.12.2023 04:15, Stefano Stabellini wrote:
> On Tue, 5 Dec 2023, Federico Serafini wrote:
>> --- a/xen/drivers/passthrough/amd/iommu.h
>> +++ b/xen/drivers/passthrough/amd/iommu.h
>> @@ -138,10 +138,12 @@ struct ivrs_mappings {
>>  extern unsigned int ivrs_bdf_entries;
>>  extern u8 ivhd_type;
>>  
>> -struct ivrs_mappings *get_ivrs_mappings(u16 seg);
>> -int iterate_ivrs_mappings(int (*)(u16 seg, struct ivrs_mappings *));
>> -int iterate_ivrs_entries(int (*)(const struct amd_iommu *,
>> -                                 struct ivrs_mappings *, uint16_t));
>> +struct ivrs_mappings *get_ivrs_mappings(uint16_t seg);
>> +int iterate_ivrs_mappings(int (*handler)(uint16_t seg,
>> +                                         struct ivrs_mappings *map));
>> +int iterate_ivrs_entries(int (*handler)(const struct amd_iommu *iommu,
>> +                                        struct ivrs_mappings *map,
>> +                                        uint16_t bdf));

(Note this for the comment near the end.)

>> @@ -361,14 +362,15 @@ static int iommu_read_log(struct amd_iommu *iommu,
>>  
>>   out:
>>      spin_unlock(&log->lock);
>> -   
>> +
>>      return 0;
>>  }
>>  
>>  /* reset event log or ppr log when overflow */
>>  static void iommu_reset_log(struct amd_iommu *iommu,
>>                              struct ring_buffer *log,
>> -                            void (*ctrl_func)(struct amd_iommu *iommu, 
>> bool))
>> +                            void (*ctrl_func)(struct amd_iommu *iommu,
>> +                                              bool iommu_control))
> 
> instead of iommu_control it should be iommu_enable ?

What purpose would "iommu_" serve? It would be actively confusing, for
colliding with the same-name global we have. Both functions passed here
use simply "enable".

>> @@ -1158,14 +1160,15 @@ static void __init amd_iommu_init_cleanup(void)
>>      iommuv2_enabled = 0;
>>  }
>>  
>> -struct ivrs_mappings *get_ivrs_mappings(u16 seg)
>> +struct ivrs_mappings *get_ivrs_mappings(uint16_t seg)
>>  {
>>      return radix_tree_lookup(&ivrs_maps, seg);
>>  }
>>  
>> -int iterate_ivrs_mappings(int (*handler)(u16 seg, struct ivrs_mappings *))
>> +int iterate_ivrs_mappings(int (*handler)(uint16_t seg,
>> +                                         struct ivrs_mappings *map))
> 
> Instead of map it should be ivrs_mappings ? Actually it reads better as
> map and I know it is not a MISRA requirement to have function pointer
> args match. I'll leave this one to Jan.

The name is entirely meaningless here (i.e. not helping with anything),
so imo "map" is not only fine but also (see above) consistent with other
code.

Jan



 


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