linux-kernel - Re: [PATCH v12 1/6] PCI: Introduce generic bus config read helper function

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <93896043-2b25-4fbc-8102-b67ab3a3b973@163.com>
Date: Tue, 3 Jun 2025 23:41:29 +0800
From: Hans Zhang <18255117159@....com>
To: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Cc: lpieralisi@...nel.org, bhelgaas@...gle.com,
 manivannan.sadhasivam@...aro.org, kw@...ux.com, cassel@...nel.org,
 robh@...nel.org, jingoohan1@...il.com, linux-pci@...r.kernel.org,
 LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v12 1/6] PCI: Introduce generic bus config read helper
 function



On 2025/6/3 17:21, Ilpo Järvinen wrote:
> On Tue, 3 Jun 2025, Ilpo Järvinen wrote:
> 
>> On Thu, 15 May 2025, Hans Zhang wrote:
>>
>>> The primary PCI config space accessors are tied to the size of the read
>>> (byte/word/dword). Upcoming refactoring of PCI capability discovery logic
>>> requires passing a config accessor function that must be able to perform
>>> read with different sizes.
>>>
>>> Add any size config space read accessor pci_bus_read_config() to allow
>>> giving it as the config space accessor to the upcoming PCI capability
>>> discovery macro.
>>>
>>> Reconstructs the PCI function discovery logic to prepare for unified
>>> configuration of access modes. No function changes are intended.
>>>
>>> Signed-off-by: Hans Zhang <18255117159@....com>
>>> ---
>>> Changes since v9 ~ v11:
>>> - None
>>>
>>> Changes since v8:
>>> - The new split is patch 1/6.
>>> - The patch commit message were modified.
>>> ---
>>>   drivers/pci/access.c | 17 +++++++++++++++++
>>>   drivers/pci/pci.h    |  2 ++
>>>   2 files changed, 19 insertions(+)
>>>
>>> diff --git a/drivers/pci/access.c b/drivers/pci/access.c
>>> index b123da16b63b..603332658ab3 100644
>>> --- a/drivers/pci/access.c
>>> +++ b/drivers/pci/access.c
>>> @@ -85,6 +85,23 @@ EXPORT_SYMBOL(pci_bus_write_config_byte);
>>>   EXPORT_SYMBOL(pci_bus_write_config_word);
>>>   EXPORT_SYMBOL(pci_bus_write_config_dword);
>>>   
>>> +int pci_bus_read_config(void *priv, unsigned int devfn, int where, u32 size,
>>> +			u32 *val)
>>> +{
>>> +	struct pci_bus *bus = priv;
>>> +	int ret;
>>> +
>>> +	if (size == 1)
>>> +		ret = pci_bus_read_config_byte(bus, devfn, where, (u8 *)val);
>>> +	else if (size == 2)
>>> +		ret = pci_bus_read_config_word(bus, devfn, where, (u16 *)val);
>>> +	else
>>> +		ret = pci_bus_read_config_dword(bus, devfn, where, val);
>>
>> Perhaps this should check also size == 4 and return
>> PCIBIOS_BAD_REGISTER_NUMBER in case size is wrong.
>>
>>> +
>>> +	return ret;
> 
> I'd also forgo ret variable and return directly.


Dear Ilpo,

Will delete ret.

Best regards,
Hans

> 
>>> +}
>>> +EXPORT_SYMBOL_GPL(pci_bus_read_config);
>>
>> Does this even need to be exported? Isn't the capability search always
>> built in?
>>
>>>   int pci_generic_config_read(struct pci_bus *bus, unsigned int devfn,
>>>   			    int where, int size, u32 *val)
>>>   {
>>> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
>>> index b81e99cd4b62..5e1477d6e254 100644
>>> --- a/drivers/pci/pci.h
>>> +++ b/drivers/pci/pci.h
>>> @@ -88,6 +88,8 @@ extern bool pci_early_dump;
>>>   bool pcie_cap_has_lnkctl(const struct pci_dev *dev);
>>>   bool pcie_cap_has_lnkctl2(const struct pci_dev *dev);
>>>   bool pcie_cap_has_rtctl(const struct pci_dev *dev);
>>> +int pci_bus_read_config(void *priv, unsigned int devfn, int where, u32 size,
>>> +			u32 *val);
>>>   
>>>   /* Functions internal to the PCI core code */
>>>   
>>>
>>
>>
>