Re: [PATCH] x86/pci: make pci_mem_start to be aligned only -v4

[Yinghai Lu]

Ivan Kokshaysky wrote:
> On Sun, Apr 19, 2009 at 11:06:15AM +0200, Ingo Molnar wrote:
>> Hm, there's one patch in that lot that does:
>>
>>  drivers/pci/bus.c	 |    8 +++++++-
>>  drivers/pci/probe.c     |    8 ++++++--
>>  drivers/pci/setup-bus.c |   40 +++++++++++++++++++++++++++++++---------
>>  3 files changed, 44 insertions(+), 12 deletions(-)
>>
>> Which should go via the PCI tree.
> 
> Here is a replacement for that patch which doesn't touch
> the generic code.
> 
> Ivan.
> 
> ---
> x86 pci: first cut on 64-bit resource allocation
> 
> I believe that we should consider PCI memory above 4G as yet another
> type of address space. This actually makes sense, as even accesses to that
> memory are physically different - Dual Address Cycle (DAC) vs. 32-bit
> Single Address Cycle (SAC).
> 
> So, platform that can deal with 64-bit allocations would set up an
> additional root bus resource and mark it with IORESOURCE_MEM64 flag.
> 
> The main problem here is how the kernel would detect that hardware can
> actually access a DAC memory (I know for a fact that a lot of Intel chipsets
> cannot access MMIO >4G, even though subordinate p2p bridges are 64-bit
> capable).
> On the other hand, there are PCI devices with 64-bit BARs that do not
> work properly being placed above 4G boundary. For example, some
> radeon cards have 64-bit BAR for video RAM, but allocating that BAR in
> the DAC area doesn't work for various reasons, like video-BIOS
> limitations or drivers not taking into account that GPU is 32-bit.
> 
> So moving stuff into MEM64 area should be considered as generally unsafe
> operation, and the best default policy is to not enable MEM64 resource
> unless we find that BIOS has allocated something there.
> At the same time, MEM64 can be easily enabled/disabled based on host
> bridge PCI IDs, kernel command line options and so on.
> 
> Here is a basic implementation of the above for x86. I think it's
> reasonably good starting point for PCI64 work - the next step would
> be to teach pci_bus_alloc_resource() about IORESOURCE_MEM64: logic is
> similar to prefetch vs non-prefetch case - MEM can hold MEM64 resource,
> but not vice versa. And eventually bridge sizing code will be updated
> for reasonable 64-bit allocations (it's a non-trivial task, though).
> 
> This patch alone should fix cardbus >4G allocations and similar
> nonsense.
> 
> Signed-off-by: Ivan Kokshaysky <ink@xxxxxxxxxxxxxxxxxxxx>
> ---
>  arch/x86/include/asm/pci.h |    8 ++++++++
>  arch/x86/pci/Makefile      |    2 ++
>  arch/x86/pci/dac_64bit.c   |   44 ++++++++++++++++++++++++++++++++++++++++++++
>  arch/x86/pci/i386.c        |   10 ++++++++++
>  include/linux/ioport.h     |    2 ++
>  5 files changed, 66 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/x86/include/asm/pci.h b/arch/x86/include/asm/pci.h
> index b51a1e8..5a9c54e 100644
> --- a/arch/x86/include/asm/pci.h
> +++ b/arch/x86/include/asm/pci.h
> @@ -86,6 +86,14 @@ static inline void early_quirks(void) { }
>  
>  extern void pci_iommu_alloc(void);
>  
> +#ifdef CONFIG_ARCH_PHYS_ADDR_T_64BIT
> +extern void pcibios_pci64_setup(void);
> +extern void pcibios_pci64_verify(void);
> +#else
> +static inline void pcibios_pci64_setup(void) { }
> +static inline void pcibios_pci64_verify(void) { }
> +#endif
> +
>  /* MSI arch hook */
>  #define arch_setup_msi_irqs arch_setup_msi_irqs
>  
> diff --git a/arch/x86/pci/Makefile b/arch/x86/pci/Makefile
> index d49202e..1b6c576 100644
> --- a/arch/x86/pci/Makefile
> +++ b/arch/x86/pci/Makefile
> @@ -13,5 +13,7 @@ obj-$(CONFIG_X86_VISWS)		+= visws.o
>  
>  obj-$(CONFIG_X86_NUMAQ)		+= numaq_32.o
>  
> +obj-$(CONFIG_ARCH_PHYS_ADDR_T_64BIT)	+= dac_64bit.o
> +
>  obj-y				+= common.o early.o
>  obj-y				+= amd_bus.o
> diff --git a/arch/x86/pci/dac_64bit.c b/arch/x86/pci/dac_64bit.c
> new file mode 100644
> index 0000000..ee03c4a
> --- /dev/null
> +++ b/arch/x86/pci/dac_64bit.c
> @@ -0,0 +1,44 @@
> +/*
> + * Set up the 64-bit bus resource for allocations > 4G if the hardware
> + * is capable of generating Dual Address Cycle (DAC).
> + */
> +
> +#include <linux/pci.h>
> +
> +static struct resource mem64 = {
> +	.name	= "PCI mem64",
> +	.start	= (resource_size_t)1 << 32,	/* 4Gb */
> +	.end	= -1,
> +	.flags	= IORESOURCE_MEM,
> +};
> +
> +void pcibios_pci64_setup(void)
> +{
> +	struct resource *r64 = &mem64, *root = &iomem_resource;
> +	struct pci_bus *b;
> +
> +	if (insert_resource(root, r64)) {
> +		printk(KERN_WARNING "PCI: Failed to allocate PCI64 space\n");
> +		return;
> +	}
> +
> +	list_for_each_entry(b, &pci_root_buses, node) {
> +		/* Is this a "standard" root bus created by pci_create_bus? */
> +		if (b->resource[1] != root || b->resource[2])
> +			continue;
> +		b->resource[2] = r64;	/* create DAC resource */
> +	}
> +}
> +
> +void pcibios_pci64_verify(void)
> +{
> +	struct pci_bus *b;
> +
> +	if (mem64.flags & IORESOURCE_MEM64)
> +		return;		/* presumably DAC works */
> +	list_for_each_entry(b, &pci_root_buses, node) {
> +		if (b->resource[2] == &mem64)
> +			b->resource[2] = NULL;
> +	}
> +	printk(KERN_INFO "PCI: allocations above 4G disabled\n");
> +}
> diff --git a/arch/x86/pci/i386.c b/arch/x86/pci/i386.c
> index f1817f7..bf8eb75 100644
> --- a/arch/x86/pci/i386.c
> +++ b/arch/x86/pci/i386.c
> @@ -137,6 +137,10 @@ static void __init pcibios_allocate_bus_resources(struct list_head *bus_list)
>  					 * range.
>  					 */
>  					r->flags = 0;
> +				} else {
> +					/* Successful allocation */
> +					if (upper_32_bits(r->start))
> +						pr->flags |= IORESOURCE_MEM64;
>  				}
>  			}
>  		}
> @@ -174,6 +178,10 @@ static void __init pcibios_allocate_resources(int pass)
>  					/* We'll assign a new address later */
>  					r->end -= r->start;
>  					r->start = 0;
> +				} else {
> +					/* Successful allocation */
> +					if (upper_32_bits(r->start))
> +						pr->flags |= IORESOURCE_MEM64;
>  				}
>  			}
>  		}
> @@ -225,9 +233,11 @@ static int __init pcibios_assign_resources(void)
>  void __init pcibios_resource_survey(void)
>  {
>  	DBG("PCI: Allocating resources\n");
> +	pcibios_pci64_setup();
>  	pcibios_allocate_bus_resources(&pci_root_buses);
>  	pcibios_allocate_resources(0);
>  	pcibios_allocate_resources(1);
> +	pcibios_pci64_verify();
>  
>  	e820_reserve_resources_late();
>  }
> diff --git a/include/linux/ioport.h b/include/linux/ioport.h
> index 32e4b2f..30403b3 100644
> --- a/include/linux/ioport.h
> +++ b/include/linux/ioport.h
> @@ -49,6 +49,8 @@ struct resource_list {
>  #define IORESOURCE_SIZEALIGN	0x00020000	/* size indicates alignment */
>  #define IORESOURCE_STARTALIGN	0x00040000	/* start field is alignment */
>  
> +#define IORESOURCE_MEM64	0x00080000	/* 64-bit addressing, >4G */
> +
>  #define IORESOURCE_EXCLUSIVE	0x08000000	/* Userland may not map this resource */
>  #define IORESOURCE_DISABLED	0x10000000
>  #define IORESOURCE_UNSET	0x20000000

also it seems logical is wrong.

we should make sure if one pci resource support 64 from pci_read_bases() instead of 
pcibios_allocate_resources.

thinking about: if pci bridge on bus 0 (aka first peer root bus), some device under
bridge doesn't get allocated resource from BIOS. and those bridge/device does support pref mem64
then your patch will not getIORESORCE_MEM64 set before pcibios_pci64_verify...

Correct logic should be
record all device if support 64bit pref mem (with pci_read_bases), and make sure bridge to be
 consistent with that of device under if.
and that is my patch doing: pci: don't assume pref memio are 64bit -v2

YH

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