linux-kernel - Re: [RFC PATCH v2 1/3] ACPI: APEI: EINJ: Refactor available_error_type

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Message-ID: <2ed4a89d-e729-6e3c-8514-f33fb0a8c207@amd.com>
Date:   Thu, 8 Jun 2023 16:08:29 -0500
From:   Avadhut Naik <avadnaik@....com>
To:     Alexey Kardashevskiy <aik@....com>,
        Yazen Ghannam <yazen.ghannam@....com>,
        Avadhut Naik <Avadhut.Naik@....com>, rafael@...nel.org,
        gregkh@...uxfoundation.org, lenb@...nel.org,
        linux-acpi@...r.kernel.org, linux-fsdevel@...r.kernel.org
Cc:     alexey.kardashevskiy@....com, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH v2 1/3] ACPI: APEI: EINJ: Refactor
 available_error_type_show()

Hi,
	Thanks for reviewing.

On 6/7/2023 22:48, Alexey Kardashevskiy wrote:
> 
> 
> On 8/6/23 00:20, Yazen Ghannam wrote:
>> On 5/25/23 4:44 PM, Avadhut Naik wrote:
>>> OSPM can discover the error injection capabilities of the platform by
>>> executing GET_ERROR_TYPE error injection action.[1] The action returns
>>> a DWORD representing a bitmap of platform supported error injections.[2]
>>>
>>> The available_error_type_show() function determines the bits set within
>>> this DWORD and provides a verbose output, from einj_error_type_string
>>> array, through /sys/kernel/debug/apei/einj/available_error_type file.
>>>
>>> The function however, assumes one to one correspondence between an error's
>>> position in the bitmap and its array entry offset. Consequently, some
>>> errors like Vendor Defined Error Type fail this assumption and will
>>> incorrectly be shown as not supported, even if their corresponding bit is
>>> set in the bitmap and they have an entry in the array.
>>>
>>> Navigate around the issue by converting einj_error_type_string into an
>>> array of structures with a predetermined mask for all error types
>>> corresponding to their bit position in the DWORD returned by GET_ERROR_TYPE
>>> action. The same breaks the aforementioned assumption resulting in all
>>> supported error types by a platform being outputted through the above
>>> available_error_type file.
>>>
>>> [1] ACPI specification 6.5, Table 18.25
>>> [2] ACPI specification 6.5, Table 18.30
>>>
>>> Suggested-by: Alexey Kardashevskiy <alexey.kardashevskiy@....com>
>>> Signed-off-by: Avadhut Naik <Avadhut.Naik@....com>
>>> ---
>>>   drivers/acpi/apei/einj.c | 43 ++++++++++++++++++++--------------------
>>>   1 file changed, 22 insertions(+), 21 deletions(-)
>>>
>>> diff --git a/drivers/acpi/apei/einj.c b/drivers/acpi/apei/einj.c
>>> index 013eb621dc92..d5f8dc4df7a5 100644
>>> --- a/drivers/acpi/apei/einj.c
>>> +++ b/drivers/acpi/apei/einj.c
>>> @@ -577,25 +577,25 @@ static u64 error_param2;
>>>   static u64 error_param3;
>>>   static u64 error_param4;
>>>   static struct dentry *einj_debug_dir;
>>> -static const char * const einj_error_type_string[] = {
>>> -    "0x00000001\tProcessor Correctable\n",
>>> -    "0x00000002\tProcessor Uncorrectable non-fatal\n",
>>> -    "0x00000004\tProcessor Uncorrectable fatal\n",
>>> -    "0x00000008\tMemory Correctable\n",
>>> -    "0x00000010\tMemory Uncorrectable non-fatal\n",
>>> -    "0x00000020\tMemory Uncorrectable fatal\n",
>>> -    "0x00000040\tPCI Express Correctable\n",
>>> -    "0x00000080\tPCI Express Uncorrectable non-fatal\n",
>>> -    "0x00000100\tPCI Express Uncorrectable fatal\n",
>>> -    "0x00000200\tPlatform Correctable\n",
>>> -    "0x00000400\tPlatform Uncorrectable non-fatal\n",
>>> -    "0x00000800\tPlatform Uncorrectable fatal\n",
>>> -    "0x00001000\tCXL.cache Protocol Correctable\n",
>>> -    "0x00002000\tCXL.cache Protocol Uncorrectable non-fatal\n",
>>> -    "0x00004000\tCXL.cache Protocol Uncorrectable fatal\n",
>>> -    "0x00008000\tCXL.mem Protocol Correctable\n",
>>> -    "0x00010000\tCXL.mem Protocol Uncorrectable non-fatal\n",
>>> -    "0x00020000\tCXL.mem Protocol Uncorrectable fatal\n",
>>> +static struct { u32 mask; const char *str; } const einj_error_type_string[] = {
>>> +    {0x00000001, "Processor Correctable"},
>>> +    {0x00000002, "Processor Uncorrectable non-fatal"},
>>> +    {0x00000004, "Processor Uncorrectable fatal"},
>>> +    {0x00000008, "Memory Correctable"},
>>> +    {0x00000010, "Memory Uncorrectable non-fatal"},
>>> +    {0x00000020, "Memory Uncorrectable fatal"},
>>> +    {0x00000040, "PCI Express Correctable"},
>>> +    {0x00000080, "PCI Express Uncorrectable non-fatal"},
>>> +    {0x00000100, "PCI Express Uncorrectable fatal"},
>>> +    {0x00000200, "Platform Correctable"},
>>> +    {0x00000400, "Platform Uncorrectable non-fatal"},
>>> +    {0x00000800, "Platform Uncorrectable fatal"},
>>> +    {0x00001000, "CXL.cache Protocol Correctable"},
>>> +    {0x00002000, "CXL.cache Protocol Uncorrectable non-fatal"},
>>> +    {0x00004000, "CXL.cache Protocol Uncorrectable fatal"},
>>> +    {0x00008000, "CXL.mem Protocol Correctable"},
>>> +    {0x00010000, "CXL.mem Protocol Uncorrectable non-fatal"},
>>> +    {0x00020000, "CXL.mem Protocol Uncorrectable fatal"},
>>>   };
>>>
>>
>> I think it'd be easier to read if the masks used the BIT() macro rather
>> than a hex value.
> 
> Makes sense but I'd say because it is easier to match the APCI spec which uses the bit numbers, not easier to read (which is arguable).
> 
	Agreed, will replace the hex values with BIT() macro.

Thanks,
Avadhut Naik
> 
>>
>> Thanks,
>> Yazen
> 

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