Re: [PATCH 1/1] of/pci: Add IORESOURCE_MEM_64 to resource flags for 64-bit memory addresses

On Thu, Apr 15, 2021 at 01:59:52PM -0500, Rob Herring wrote:

On Thu, Apr 15, 2021 at 1:01 PM Leonardo Bras [off-list ref] wrote:

quoted

Many other resource flag parsers already add this flag when the input
has bits 24 & 25 set, so update this one to do the same.

[Adding this to the thread for archaeological purposes since it didn't
make it to the commit log]

The other resource flag parsers appear to be:

  pci_parse_of_flags(u32 addr0, ...)    # powerpc/kernel/pci_of_scan.c
    unsigned int as = addr0 & OF_PCI_ADDR0_SPACE_MASK;
    if (as == OF_PCI_ADDR0_SPACE_MMIO32 || as == OF_PCI_ADDR0_SPACE_MMIO64)
      flags = IORESOURCE_MEM | PCI_BASE_ADDRESS_SPACE_MEMORY;
      if (as == OF_PCI_ADDR0_SPACE_MMIO64)
        flags |= PCI_BASE_ADDRESS_MEM_TYPE_64 | IORESOURCE_MEM_64;

  pci_parse_of_flags(u32 addr0)         # sparc/kernel/pci.c
    if (addr0 & 0x02000000) {
      flags = IORESOURCE_MEM | PCI_BASE_ADDRESS_SPACE_MEMORY;
      if (addr0 & 0x01000000)
        flags |= IORESOURCE_MEM_64 | PCI_BASE_ADDRESS_MEM_TYPE_64;

  of_bus_pci_get_flags(... addr)        # drivers/of/address.c (this one)
    u32 w = be32_to_cpup(addr);
    switch((w >> 24) & 0x03) {
    case 0x02: /* 32 bits */
      flags |= IORESOURCE_MEM;
      break;
    case 0x03: /* 64 bits */
      flags |= IORESOURCE_MEM | IORESOURCE_MEM_64;
      break;

It's super annoying to have three copies of essentially the same
thing.  Even more annoying that they test the same things in three
completely different ways.  But I remember looking at this several
years ago, and it wasn't as simple to unify these as I had hoped.

Many others? Looks like sparc and powerpc to me. Those would be the
ones I worry about breaking. Sparc doesn't use of/address.c so it's
fine. Powerpc version of the flags code was only fixed in 2019, so I
don't think powerpc will care either.

I'm guessing you're referring to df5be5be8735 ("powerpc/pci/of: Fix OF
flags parsing for 64bit BARs").

I noticed both sparc and powerpc set PCI_BASE_ADDRESS_MEM_TYPE_64 in
the flags. AFAICT, that's not set anywhere outside of arch code. So
never for riscv, arm and arm64 at least. That leads me to
pci_std_update_resource() which is where the PCI code sets BARs and
just copies the flags in PCI_BASE_ADDRESS_MEM_MASK ignoring
IORESOURCE_* flags. So it seems like 64-bit is still not handled and
neither is prefetch.

quoted

Some devices (like virtio-net) have more than one memory resource
(like MMIO32 and MMIO64) and without this flag it would be needed to
verify the address range to know which one is which.

Signed-off-by: Leonardo Bras <redacted>
---
 drivers/of/address.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/of/address.c b/drivers/of/address.c
index 73ddf2540f3f..dc7147843783 100644
--- a/drivers/of/address.c
+++ b/drivers/of/address.c

@@ -116,9 +116,12 @@ static unsigned int of_bus_pci_get_flags(const __be32 *addr)
                flags |= IORESOURCE_IO;
                break;
        case 0x02: /* 32 bits */
-       case 0x03: /* 64 bits */
                flags |= IORESOURCE_MEM;
                break;
+
+       case 0x03: /* 64 bits */
+               flags |= IORESOURCE_MEM | IORESOURCE_MEM_64;
+               break;
        }
        if (w & 0x40000000)
                flags |= IORESOURCE_PREFETCH;
--

2.30.2