[RFC PATCH v2 3/3] ACPI: APEI: EINJ: Add support for vendor defined error types

[Avadhut Naik <avadnaik@amd.com>]

Hi,
	Thanks for reviewing!

On 6/7/2023 23:44, Alexey Kardashevskiy wrote:
> 
> 
> On 26/5/23 06:44, Avadhut Naik wrote:
>> Vendor-Defined Error types are supported by the platform apart from
>> standard error types if bit 31 is set in the output of GET_ERROR_TYPE
>> Error Injection Action.[1] While the errors themselves and the length
>> of their associated "OEM Defined data structure" might vary between
>> vendors, the physical address of this structure can be computed through
>> vendor_extension and length fields of "SET_ERROR_TYPE_WITH_ADDRESS" and
>> "Vendor Error Type Extension" Structures respectively.[2][3]
>>
>> Currently, however, the einj module only computes the physical address of
>> Vendor Error Type Extension Structure. Neither does it compute the physical
>> address of OEM Defined structure nor does it establish the memory mapping
>> required for injecting Vendor-defined errors. Consequently, userspace
>> tools have to establish the very mapping through /dev/mem, nopat kernel
>> parameter and system calls like mmap/munmap initially before injecting
>> Vendor-defined errors.
>>
>> Circumvent the issue by computing the physical address of OEM Defined data
>> structure and establishing the required mapping with the structure. Create
>> a new file "oem_error", if the system supports Vendor-defined errors, to
>> export this mapping, through debugfs_create_blob(). Userspace tools can
>> then populate their respective OEM Defined structure instances and just
>> write to the file as part of injecting Vendor-defined Errors.
>>
>> [1] ACPI specification 6.5, section 18.6.4
>> [2] ACPI specification 6.5, Table 18.31
>> [3] ACPI specification 6.5, Table 18.32
>>
>> Suggested-by: Yazen Ghannam <yazen.ghannam@amd.com>
>> Signed-off-by: Avadhut Naik <Avadhut.Naik@amd.com>
>> ---
>>   drivers/acpi/apei/einj.c | 19 +++++++++++++++++++
>>   1 file changed, 19 insertions(+)
>>
>> diff --git a/drivers/acpi/apei/einj.c b/drivers/acpi/apei/einj.c
>> index d5f8dc4df7a5..9f23b6955cf0 100644
>> --- a/drivers/acpi/apei/einj.c
>> +++ b/drivers/acpi/apei/einj.c
>> @@ -73,6 +73,7 @@ static u32 notrigger;
>>     static u32 vendor_flags;
>>   static struct debugfs_blob_wrapper vendor_blob;
>> +static struct debugfs_blob_wrapper vendor_errors;
>>   static char vendor_dev[64];
>>     /*
>> @@ -182,6 +183,16 @@ static int einj_timedout(u64 *t)
>>       return 0;
>>   }
>>   +static void get_oem_vendor_struct(u64 paddr, int offset,
>> +                  struct vendor_error_type_extension *v)
>> +{
>> +    u64 target_pa = paddr + offset + sizeof(struct vendor_error_type_extension);
>> +
>> +    vendor_errors.size = v->length - sizeof(struct vendor_error_type_extension);
>> +    if (vendor_errors.size)
>> +        vendor_errors.data = acpi_os_map_iomem(target_pa, vendor_errors.size);
> 
> 
> acpi_os_map_iomem() can return NULL but you check for the size (see below comments).
> 
>> +}
>> +
>>   static void check_vendor_extension(u64 paddr,
>>                      struct set_error_type_with_address *v5param)
>>   {
>> @@ -194,6 +205,7 @@ static void check_vendor_extension(u64 paddr,
>>       v = acpi_os_map_iomem(paddr + offset, sizeof(*v));
>>       if (!v)
>>           return;
>> +    get_oem_vendor_struct(paddr, offset, v);
>>       sbdf = v->pcie_sbdf;
>>       sprintf(vendor_dev, "%x:%x:%x.%x vendor_id=%x device_id=%x rev_id=%x\n",
>>           sbdf >> 24, (sbdf >> 16) & 0xff,
>> @@ -596,6 +608,7 @@ static struct { u32 mask; const char *str; } const einj_error_type_string[] = {
>>       {0x00008000, "CXL.mem Protocol Correctable"},
>>       {0x00010000, "CXL.mem Protocol Uncorrectable non-fatal"},
>>       {0x00020000, "CXL.mem Protocol Uncorrectable fatal"},
>> +    {0x80000000, "Vendor Defined Error Types"},
>>   };
>>     static int available_error_type_show(struct seq_file *m, void *v)
>> @@ -768,6 +781,10 @@ static int __init einj_init(void)
>>                      einj_debug_dir, &vendor_flags);
>>       }
>>   +    if (vendor_errors.size)
>> +        debugfs_create_blob("oem_error", 0200, einj_debug_dir,
>> +                    &vendor_errors);
> 
> Here writing to "oem_error" will crash.
> 
> 
>> +
>>       pr_info("Error INJection is initialized.\n");
>>         return 0;
>> @@ -793,6 +810,8 @@ static void __exit einj_exit(void)
>>               sizeof(struct einj_parameter);
>>             acpi_os_unmap_iomem(einj_param, size);
>> +        if (vendor_errors.size)
>> +            acpi_os_unmap_iomem(vendor_errors.data, vendor_errors.size);
> 
> And here is will produce an error message I suppose.
> 
> Just change get_oem_vendor_struct() to store the size in a local variable and only copy it to vendor_errors.size if vendor_errors.data!=NULL.
> 
> With that bit fixed,
> 
> Reviewed-by: Alexey Kardashevskiy <aik@amd.com>
> 
	Agreed. Will change the function to something like below:

static void get_oem_vendor_struct(u64 paddr, int offset,
                  struct vendor_error_type_extension *v)
{
    unsigned long vendor_size;  
    u64 target_pa = paddr + offset + sizeof(struct vendor_error_type_extension);

    vendor_size = v->length - sizeof(struct vendor_error_type_extension);

    if (vendor_size)
        vendor_errors.data = acpi_os_map_iomem(target_pa, vendor_size);

    if (vendor_errors.data)
        vendor_errors.size = vendor_size;
}

Thanks,
Avadhut Naik
> 
> 
>>       }
>>       einj_exec_ctx_init(&ctx);
>>       apei_exec_post_unmap_gars(&ctx);
> 

--