Re: [PATCH V5 2/3] ARM64 LPC: Add missing range exception for special ISA

["liviu.dudau@arm.com" <liviu.dudau@arm.com>]

On Thu, Nov 10, 2016 at 04:06:40PM +0000, Gabriele Paoloni wrote:
> Hi Liviu
> 
> > -----Original Message-----
> > From: liviu.dudau@arm.com [mailto:liviu.dudau@arm.com]
> > Sent: 09 November 2016 16:51
> > To: Gabriele Paoloni
> > Cc: Yuanzhichang; catalin.marinas@arm.com; will.deacon@arm.com;
> > robh+dt@kernel.org; bhelgaas@google.com; mark.rutland@arm.com;
> > olof@lixom.net; arnd@arndb.de; linux-arm-kernel@lists.infradead.org;
> > lorenzo.pieralisi@arm.com; linux-kernel@vger.kernel.org; Linuxarm;
> > devicetree@vger.kernel.org; linux-pci@vger.kernel.org; linux-
> > serial@vger.kernel.org; minyard@acm.org; benh@kernel.crashing.org;
> > zourongrong@gmail.com; John Garry; zhichang.yuan02@gmail.com;
> > kantyzc@163.com; xuwei (O)
> > Subject: Re: [PATCH V5 2/3] ARM64 LPC: Add missing range exception for
> > special ISA
> > 
> > On Wed, Nov 09, 2016 at 04:16:17PM +0000, Gabriele Paoloni wrote:
> > > Hi Liviu
> > >
> > > Thanks for reviewing
> > >
> > 
> > [removed some irrelevant part of discussion, avoid crazy formatting]
> > 
> > > > > +/**
> > > > > + * addr_is_indirect_io - check whether the input taddr is for
> > > > indirectIO.
> > > > > + * @taddr: the io address to be checked.
> > > > > + *
> > > > > + * Returns 1 when taddr is in the range; otherwise return 0.
> > > > > + */
> > > > > +int addr_is_indirect_io(u64 taddr)
> > > > > +{
> > > > > +	if (arm64_extio_ops->start > taddr || arm64_extio_ops->end
> > <
> > > > taddr)
> > > >
> > > > start >= taddr ?
> > >
> > > Nope... if  (taddr < arm64_extio_ops->start || taddr >
> > arm64_extio_ops->end)
> > > then taddr is outside the range [start; end] and will return 0;
> > otherwise
> > > it will return 1...
> > 
> > Oops, sorry, did not pay attention to the returned value. The check is
> > correct as it is, no need to change then.
> > 
> > >
> > > >
> > > > > +		return 0;
> > > > > +
> > > > > +	return 1;
> > > > > +}
> > > > >
> > > > >  BUILD_EXTIO(b, u8)
> > > > >
> > > > > diff --git a/drivers/of/address.c b/drivers/of/address.c
> > > > > index 02b2903..cc2a05d 100644
> > > > > --- a/drivers/of/address.c
> > > > > +++ b/drivers/of/address.c
> > > > > @@ -479,6 +479,50 @@ static int of_empty_ranges_quirk(struct
> > > > device_node *np)
> > > > >  	return false;
> > > > >  }
> > > > >
> > > > > +
> > > > > +/*
> > > > > + * of_isa_indirect_io - get the IO address from some isa reg
> > > > property value.
> > > > > + *	For some isa/lpc devices, no ranges property in ancestor
> > node.
> > > > > + *	The device addresses are described directly in their regs
> > > > property.
> > > > > + *	This fixup function will be called to get the IO address of
> > > > isa/lpc
> > > > > + *	devices when the normal of_translation failed.
> > > > > + *
> > > > > + * @parent:	points to the parent dts node;
> > > > > + * @bus:		points to the of_bus which can be used to parse
> > > > address;
> > > > > + * @addr:	the address from reg property;
> > > > > + * @na:		the address cell counter of @addr;
> > > > > + * @presult:	store the address paresed from @addr;
> > > > > + *
> > > > > + * return 1 when successfully get the I/O address;
> > > > > + * 0 will return for some failures.
> > > >
> > > > Bah, you are returning a signed int, why 0 for failure? Return a
> > > > negative value with
> > > > error codes. Otherwise change the return value into a bool.
> > >
> > > Yes we'll move to bool
> > >
> > > >
> > > > > + */
> > > > > +static int of_get_isa_indirect_io(struct device_node *parent,
> > > > > +				struct of_bus *bus, __be32 *addr,
> > > > > +				int na, u64 *presult)
> > > > > +{
> > > > > +	unsigned int flags;
> > > > > +	unsigned int rlen;
> > > > > +
> > > > > +	/* whether support indirectIO */
> > > > > +	if (!indirect_io_enabled())
> > > > > +		return 0;
> > > > > +
> > > > > +	if (!of_bus_isa_match(parent))
> > > > > +		return 0;
> > > > > +
> > > > > +	flags = bus->get_flags(addr);
> > > > > +	if (!(flags & IORESOURCE_IO))
> > > > > +		return 0;
> > > > > +
> > > > > +	/* there is ranges property, apply the normal translation
> > > > directly. */
> > > >
> > > > s/there is ranges/if we have a 'ranges'/
> > >
> > > Thanks for spotting this
> > >
> > > >
> > > > > +	if (of_get_property(parent, "ranges", &rlen))
> > > > > +		return 0;
> > > > > +
> > > > > +	*presult = of_read_number(addr + 1, na - 1);
> > > > > +	/* this fixup is only valid for specific I/O range. */
> > > > > +	return addr_is_indirect_io(*presult);
> > > > > +}
> > > > > +
> > > > >  static int of_translate_one(struct device_node *parent, struct
> > > > of_bus *bus,
> > > > >  			    struct of_bus *pbus, __be32 *addr,
> > > > >  			    int na, int ns, int pna, const char *rprop)
> > > > > @@ -595,6 +639,15 @@ static u64 __of_translate_address(struct
> > > > device_node *dev,
> > > > >  			result = of_read_number(addr, na);
> > > > >  			break;
> > > > >  		}
> > > > > +		/*
> > > > > +		 * For indirectIO device which has no ranges
> > property, get
> > > > > +		 * the address from reg directly.
> > > > > +		 */
> > > > > +		if (of_get_isa_indirect_io(dev, bus, addr, na,
> > &result)) {
> > > > > +			pr_debug("isa indirectIO matched(%s)..addr =
> > > > 0x%llx\n",
> > > > > +				of_node_full_name(dev), result);
> > > > > +			break;
> > > > > +		}
> > > > >
> > > > >  		/* Get new parent bus and counts */
> > > > >  		pbus = of_match_bus(parent);
> > > > > @@ -688,8 +741,9 @@ static int __of_address_to_resource(struct
> > > > device_node *dev,
> > > > >  	if (taddr == OF_BAD_ADDR)
> > > > >  		return -EINVAL;
> > > > >  	memset(r, 0, sizeof(struct resource));
> > > > > -	if (flags & IORESOURCE_IO) {
> > > > > +	if (flags & IORESOURCE_IO && taddr >= PCIBIOS_MIN_IO) {
> > > > >  		unsigned long port;
> > > > > +
> > > > >  		port = pci_address_to_pio(taddr);
> > > > >  		if (port == (unsigned long)-1)
> > > > >  			return -EINVAL;
> > > > > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> > > > > index ba34907..1a08511 100644
> > > > > --- a/drivers/pci/pci.c
> > > > > +++ b/drivers/pci/pci.c
> > > > > @@ -3263,7 +3263,7 @@ int __weak
> > pci_register_io_range(phys_addr_t
> > > > addr, resource_size_t size)
> > > > >
> > > > >  #ifdef PCI_IOBASE
> > > > >  	struct io_range *range;
> > > > > -	resource_size_t allocated_size = 0;
> > > > > +	resource_size_t allocated_size = PCIBIOS_MIN_IO;
> > > > >
> > > > >  	/* check if the range hasn't been previously recorded */
> > > > >  	spin_lock(&io_range_lock);
> > > > > @@ -3312,7 +3312,7 @@ phys_addr_t pci_pio_to_address(unsigned
> > long
> > > > pio)
> > > > >
> > > > >  #ifdef PCI_IOBASE
> > > > >  	struct io_range *range;
> > > > > -	resource_size_t allocated_size = 0;
> > > > > +	resource_size_t allocated_size = PCIBIOS_MIN_IO;
> > > >
> > > > Have you checked that pci_pio_to_address still returns valid values
> > > > after this? I know that
> > > > you are trying to take into account PCIBIOS_MIN_IO limit when
> > > > allocating reserving the IO ranges,
> > > > but the values added in the io_range_list are still starting from
> > zero,
> > > > no from PCIBIOS_MIN_IO,
> > >
> > > I think you're wrong here as in pci_address_to_pio we have:
> > > +	resource_size_t offset = PCIBIOS_MIN_IO;
> > >
> > > This should be enough to guarantee that the PIOs start at
> > > PCIBIOS_MIN_IO...right?
> > 
> > I don't think you can guarantee that the pio value that gets passed
> > into
> > pci_pio_to_address() always comes from a previously returned value by
> > pci_address_to_pio(). Maybe you can add a check in pci_pio_to_address()
> 
> Maybe I am missing something...could you make an exampleof a case
> where an IO toke doesn’t come from pci_address_to_pio() ?

Don't know, maybe it is coming from some DT or platform data? I was just
asking for confirmation that no one has seen issues there, I'm not saying
I've seen it happening.

Best regards,
Liviu

> 
> Thanks
> 
> Gab
> 
> 
> > 
> > 	if (pio < PCIBIOS_MIN_IO)
> > 		return address;
> > 
> > to avoid adding more checks in the list_for_each_entry() loop.
> > 
> > Best regards,
> > Liviu
> > 
> > >
> > >
> > > > so the calculation of the address in this function could return
> > > > negative values casted to pci_addr_t.
> > > >
> > > > Maybe you want to adjust the range->start value in
> > > > pci_register_io_range() as well to have it
> > > > offset by PCIBIOS_MIN_IO as well.
> > > >
> > > > Best regards,
> > > > Liviu
> > > >
> > > > >
> > > > >  	if (pio > IO_SPACE_LIMIT)
> > > > >  		return address;
> > > > > @@ -3335,7 +3335,7 @@ unsigned long __weak
> > > > pci_address_to_pio(phys_addr_t address)
> > > > >  {
> > > > >  #ifdef PCI_IOBASE
> > > > >  	struct io_range *res;
> > > > > -	resource_size_t offset = 0;
> > > > > +	resource_size_t offset = PCIBIOS_MIN_IO;
> > > > >  	unsigned long addr = -1;
> > > > >
> > > > >  	spin_lock(&io_range_lock);
> > > > > diff --git a/include/linux/of_address.h
> > b/include/linux/of_address.h
> > > > > index 3786473..deec469 100644
> > > > > --- a/include/linux/of_address.h
> > > > > +++ b/include/linux/of_address.h
> > > > > @@ -24,6 +24,23 @@ struct of_pci_range {
> > > > >  #define for_each_of_pci_range(parser, range) \
> > > > >  	for (; of_pci_range_parser_one(parser, range);)
> > > > >
> > > > > +
> > > > > +#ifndef indirect_io_enabled
> > > > > +#define indirect_io_enabled indirect_io_enabled
> > > > > +static inline bool indirect_io_enabled(void)
> > > > > +{
> > > > > +	return false;
> > > > > +}
> > > > > +#endif
> > > > > +
> > > > > +#ifndef addr_is_indirect_io
> > > > > +#define addr_is_indirect_io addr_is_indirect_io
> > > > > +static inline int addr_is_indirect_io(u64 taddr)
> > > > > +{
> > > > > +	return 0;
> > > > > +}
> > > > > +#endif
> > > > > +
> > > > >  /* Translate a DMA address from device space to CPU space */
> > > > >  extern u64 of_translate_dma_address(struct device_node *dev,
> > > > >  				    const __be32 *in_addr);
> > > > > diff --git a/include/linux/pci.h b/include/linux/pci.h
> > > > > index 0e49f70..7f6bbb6 100644
> > > > > --- a/include/linux/pci.h
> > > > > +++ b/include/linux/pci.h
> > > > > @@ -2130,4 +2130,12 @@ static inline bool pci_ari_enabled(struct
> > > > pci_bus *bus)
> > > > >  /* provide the legacy pci_dma_* API */
> > > > >  #include <linux/pci-dma-compat.h>
> > > > >
> > > > > +/*
> > > > > + * define this macro here to refrain from compilation error for
> > some
> > > > > + * platforms. Please keep this macro at the end of this header
> > file.
> > > > > + */
> > > > > +#ifndef PCIBIOS_MIN_IO
> > > > > +#define PCIBIOS_MIN_IO		0
> > > > > +#endif
> > > > > +
> > > > >  #endif /* LINUX_PCI_H */
> > > > > --
> > > > > 1.9.1
> > > > >
> > > > > --
> > > > > To unsubscribe from this list: send the line "unsubscribe linux-
> > pci"
> > > > in
> > > > > the body of a message to majordomo@vger.kernel.org
> > > > > More majordomo info at  http://vger.kernel.org/majordomo-
> > info.html
> > 
> > --
> > ====================
> > | I would like to |
> > | fix the world,  |
> > | but they're not |
> > | giving me the   |
> >  \ source code!  /
> >   ---------------
> >     ¯\_(ツ)_/¯

-- 
====================
| I would like to |
| fix the world,  |
| but they're not |
| giving me the   |
 \ source code!  /
  ---------------
    ¯\_(ツ)_/¯