Re: [PATCH v3 1/5] ARM/PCI: remove align_resource callback in pcibios_align_resource

[Zhou Wang <wangzhou1@hisilicon.com>]

On 2015/7/3 1:50, Liviu Dudau wrote:
> On Wed, Jul 01, 2015 at 10:43:33AM +0100, Zhou Wang wrote:
>> This patch had added by Arnd Bergmann during last reviewing of v1 patchset[1].
>>
>> PCI core codes call pcibios_align_resource(). In ARM specific one, it will
>> dereference pci_sys_data and call sys->align_resource. If we try to unify ARM
>> and ARM64 PCIe API in pcie-designware. it will bring kernel crash when run into
>> this dereferencing.
>>
>> However, in ARM there is only pci-mvebu which implements align_resource. So
>> add align_resource call back in pci_host_bridge structure and override
>> pcibios_align_resource with it.
>>
>> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
>> Signed-off-by: Zhou Wang <wangzhou1@hisilicon.com>
>> Tested-by: Fabrice Gasnier <fabrice.gasnier@st.com>
>>
>> [1] http://www.spinics.net/lists/linux-pci/msg41671.html
>> ---
>>  arch/arm/kernel/bios32.c     |  6 ------
>>  drivers/pci/host/pci-mvebu.c | 47 ++++++++++++++++++++++++++++----------------
>>  drivers/pci/setup-res.c      | 27 ++++++++++++++++++++-----
>>  include/linux/pci.h          |  3 +++
>>  4 files changed, 55 insertions(+), 28 deletions(-)
>>
>> diff --git a/arch/arm/kernel/bios32.c b/arch/arm/kernel/bios32.c
>> index fcbbbb1..b01189f 100644
>> --- a/arch/arm/kernel/bios32.c
>> +++ b/arch/arm/kernel/bios32.c
>> @@ -468,7 +468,6 @@ static void pcibios_init_hw(struct device *parent, struct hw_pci *hw,
>>  		sys->busnr   = busnr;
>>  		sys->swizzle = hw->swizzle;
>>  		sys->map_irq = hw->map_irq;
>> -		sys->align_resource = hw->align_resource;
>>  		INIT_LIST_HEAD(&sys->resources);
>>  
>>  		if (hw->private_data)
>> @@ -588,8 +587,6 @@ char * __init pcibios_setup(char *str)
>>  resource_size_t pcibios_align_resource(void *data, const struct resource *res,
>>  				resource_size_t size, resource_size_t align)
>>  {
>> -	struct pci_dev *dev = data;
>> -	struct pci_sys_data *sys = dev->sysdata;
>>  	resource_size_t start = res->start;
>>  
>>  	if (res->flags & IORESOURCE_IO && start & 0x300)
>> @@ -597,9 +594,6 @@ resource_size_t pcibios_align_resource(void *data, const struct resource *res,
>>  
>>  	start = (start + align - 1) & ~(align - 1);
>>  
>> -	if (sys->align_resource)
>> -		return sys->align_resource(dev, res, start, size, align);
>> -
>>  	return start;
>>  }
>>  
>> diff --git a/drivers/pci/host/pci-mvebu.c b/drivers/pci/host/pci-mvebu.c
>> index 1ab8635..155d05f 100644
>> --- a/drivers/pci/host/pci-mvebu.c
>> +++ b/drivers/pci/host/pci-mvebu.c
>> @@ -22,6 +22,8 @@
>>  #include <linux/of_pci.h>
>>  #include <linux/of_platform.h>
>>  
>> +#include "../pci.h" /* HACK to see pci_find_host_bridge */
>> +
>>  /*
>>   * PCIe unit register offsets.
>>   */
>> @@ -751,27 +753,20 @@ static int mvebu_pcie_setup(int nr, struct pci_sys_data *sys)
>>  	return 1;
>>  }
>>  
>> -static struct pci_bus *mvebu_pcie_scan_bus(int nr, struct pci_sys_data *sys)
>> +static resource_size_t mvebu_pcie_align_resource(void *data,
>> +						 const struct resource *res,
>> +						 resource_size_t size,
>> +						 resource_size_t align)
>>  {
>> -	struct mvebu_pcie *pcie = sys_to_pcie(sys);
>> -	struct pci_bus *bus;
>> +	struct pci_dev *dev = data;
>>  
>> -	bus = pci_create_root_bus(&pcie->pdev->dev, sys->busnr,
>> -				  &mvebu_pcie_ops, sys, &sys->resources);
>> -	if (!bus)
>> -		return NULL;
>> +	resource_size_t start = res->start;
>>  
>> -	pci_scan_child_bus(bus);
>> +	if (res->flags & IORESOURCE_IO && start & 0x300)
>> +		start = (start + 0x3ff) & ~0x3ff;
>>  
>> -	return bus;
>> -}
>> +	start = (start + align - 1) & ~(align - 1);
> 
> Honestly, I don't see here anything that is mvebu specific. Could you move

What I mean is that there is only mvebu who implemented sys->align_resource callback in ARM
arch.

> this function in the generic pci/host area and have a flag in the pci_host_bridge
> structure whether the function should be called or not? I know that in a way
> that looks very close to the existing implementation which uses pcibios_align_resource,

I am confused about "the existing implementation". Now pcibios_align_resource are
implemented by each arch code and are called directly. Did I miss anything about
pcibios_align_resource?

Best rgards,
Zhou

> but the problem with pcibios_ version is that it is arch specific and not driver
> specific the way we want.
> 
> Having this version as a generic implementation would also remove at least 2 more
> arch version, possibly more after testing by the arch maintainers.
> 
> Best regards,
> Liviu
> 
>>  
>> -static resource_size_t mvebu_pcie_align_resource(struct pci_dev *dev,
>> -						 const struct resource *res,
>> -						 resource_size_t start,
>> -						 resource_size_t size,
>> -						 resource_size_t align)
>> -{
>>  	if (dev->bus->number != 0)
>>  		return start;
>>  
>> @@ -796,6 +791,25 @@ static resource_size_t mvebu_pcie_align_resource(struct pci_dev *dev,
>>  		return start;
>>  }
>>  
>> +static struct pci_bus *mvebu_pcie_scan_bus(int nr, struct pci_sys_data *sys)
>> +{
>> +	struct mvebu_pcie *pcie = sys_to_pcie(sys);
>> +	struct pci_host_bridge *phb;
>> +	struct pci_bus *bus;
>> +
>> +	bus = pci_create_root_bus(&pcie->pdev->dev, sys->busnr,
>> +				  &mvebu_pcie_ops, sys, &sys->resources);
>> +	if (!bus)
>> +		return NULL;
>> +
>> +	phb = pci_find_host_bridge(bus);
>> +	phb->align_resource = mvebu_pcie_align_resource;
>> +
>> +	pci_scan_child_bus(bus);
>> +
>> +	return bus;
>> +}
>> +
>>  static void mvebu_pcie_enable(struct mvebu_pcie *pcie)
>>  {
>>  	struct hw_pci hw;
>> @@ -812,7 +826,6 @@ static void mvebu_pcie_enable(struct mvebu_pcie *pcie)
>>  	hw.scan           = mvebu_pcie_scan_bus;
>>  	hw.map_irq        = of_irq_parse_and_map_pci;
>>  	hw.ops            = &mvebu_pcie_ops;
>> -	hw.align_resource = mvebu_pcie_align_resource;
>>  
>>  	pci_common_init(&hw);
>>  }
>> diff --git a/drivers/pci/setup-res.c b/drivers/pci/setup-res.c
>> index 232f925..73abca7 100644
>> --- a/drivers/pci/setup-res.c
>> +++ b/drivers/pci/setup-res.c
>> @@ -200,7 +200,11 @@ static int pci_revert_fw_address(struct resource *res, struct pci_dev *dev,
>>  }
>>  
>>  static int __pci_assign_resource(struct pci_bus *bus, struct pci_dev *dev,
>> -		int resno, resource_size_t size, resource_size_t align)
>> +		int resno, resource_size_t size, resource_size_t align,
>> +		resource_size_t (*alignf)(void *,
>> +					  const struct resource *,
>> +					  resource_size_t,
>> +					  resource_size_t))
>>  {
>>  	struct resource *res = dev->resource + resno;
>>  	resource_size_t min;
>> @@ -217,7 +221,7 @@ static int __pci_assign_resource(struct pci_bus *bus, struct pci_dev *dev,
>>  	 */
>>  	ret = pci_bus_alloc_resource(bus, res, size, align, min,
>>  				     IORESOURCE_PREFETCH | IORESOURCE_MEM_64,
>> -				     pcibios_align_resource, dev);
>> +				     alignf, dev);
>>  	if (ret == 0)
>>  		return 0;
>>  
>> @@ -229,7 +233,7 @@ static int __pci_assign_resource(struct pci_bus *bus, struct pci_dev *dev,
>>  	     (IORESOURCE_PREFETCH | IORESOURCE_MEM_64)) {
>>  		ret = pci_bus_alloc_resource(bus, res, size, align, min,
>>  					     IORESOURCE_PREFETCH,
>> -					     pcibios_align_resource, dev);
>> +					     alignf, dev);
>>  		if (ret == 0)
>>  			return 0;
>>  	}
>> @@ -242,7 +246,7 @@ static int __pci_assign_resource(struct pci_bus *bus, struct pci_dev *dev,
>>  	 */
>>  	if (res->flags & (IORESOURCE_PREFETCH | IORESOURCE_MEM_64))
>>  		ret = pci_bus_alloc_resource(bus, res, size, align, min, 0,
>> -					     pcibios_align_resource, dev);
>> +					     alignf, dev);
>>  
>>  	return ret;
>>  }
>> @@ -251,10 +255,23 @@ static int _pci_assign_resource(struct pci_dev *dev, int resno,
>>  				resource_size_t size, resource_size_t min_align)
>>  {
>>  	struct pci_bus *bus;
>> +	struct pci_host_bridge *phb;
>> +	resource_size_t (*alignf)(void *,
>> +				  const struct resource *,
>> +				  resource_size_t,
>> +				  resource_size_t);
>>  	int ret;
>>  
>>  	bus = dev->bus;
>> -	while ((ret = __pci_assign_resource(bus, dev, resno, size, min_align))) {
>> +	phb = pci_find_host_bridge(bus);
>> +
>> +	if (phb->align_resource)
>> +		alignf = phb->align_resource;
>> +	else
>> +		alignf = pcibios_align_resource;
>> +
>> +	while ((ret = __pci_assign_resource(bus, dev, resno, size,
>> +					    min_align, alignf))) {
>>  		if (!bus->parent || !bus->self->transparent)
>>  			break;
>>  		bus = bus->parent;
>> diff --git a/include/linux/pci.h b/include/linux/pci.h
>> index 353db8d..39e48fc 100644
>> --- a/include/linux/pci.h
>> +++ b/include/linux/pci.h
>> @@ -404,6 +404,9 @@ struct pci_host_bridge {
>>  	struct device dev;
>>  	struct pci_bus *bus;		/* root bus */
>>  	struct list_head windows;	/* resource_entry */
>> +	resource_size_t (*align_resource)(void *data,
>> +			 const struct resource *res,
>> +			 resource_size_t size, resource_size_t align);
>>  	void (*release_fn)(struct pci_host_bridge *);
>>  	void *release_data;
>>  	unsigned int ignore_reset_delay:1;	/* for entire hierarchy */
>> -- 
>> 1.9.1
>>
>