On Mon, Nov 19, 2018 at 5:50 PM Robin Murphy [off-list ref] wrote:

On 19/11/2018 14:18, Ramon Fried wrote:

quoted

On Tue, Oct 9, 2018 at 8:02 AM Benjamin Herrenschmidt
[off-list ref] wrote:

quoted

On Wed, 2018-10-03 at 16:10 -0700, Alexander Duyck wrote:

quoted

quoted

-        * Because 32-bit DMA masks are so common we expect every architecture
-        * to be able to satisfy them - either by not supporting more physical
-        * memory, or by providing a ZONE_DMA32.  If neither is the case, the
-        * architecture needs to use an IOMMU instead of the direct mapping.
-        */
-       if (mask < phys_to_dma(dev, DMA_BIT_MASK(32)))
+       u64 min_mask;
+
+       if (IS_ENABLED(CONFIG_ZONE_DMA))
+               min_mask = DMA_BIT_MASK(ARCH_ZONE_DMA_BITS);
+       else
+               min_mask = DMA_BIT_MASK(32);
+
+       min_mask = min_t(u64, min_mask, (max_pfn - 1) << PAGE_SHIFT);
+
+       if (mask >= phys_to_dma(dev, min_mask))
                  return 0;
-#endif
          return 1;
   }

So I believe I have run into the same issue that Guenter reported. On
an x86_64 system w/ Intel IOMMU. I wasn't able to complete boot and
all probe attempts for various devices were failing with -EIO errors.

I believe the last mask check should be "if (mask < phys_to_dma(dev,
min_mask))" not a ">=" check.

Right, that test is backwards. I needed to change it here too (powermac
with the rest of the powerpc series).

Cheers,
Ben.

Hi, I'm working on a MIPS64 soc with PCIe root complex on it, and it
appears that this series of patches are causing all PCI drivers that
request 64bit mask to fail with -5.
It's broken in 4.19. However, I just checked, it working on master.
We may need to backport a couple of patches to 4.19. I'm not sure
though which patches should be backported as there were at least 10
patches resolving this dma_direct area recently.
Christoph, Robin.
Can we ask Greg to backport all these changes ? What do you think ?

As far as I'm aware, the only real issue in 4.19 was my subtle breakage
around setting bus_dma_mask - that's fixed by 6778be4e5209, which
according to my inbox got picked up by autosel for 4.19 stable last week.

Robin.

Yep, 6778be4e5209 fixes the issue.
Thanks a lot !
Ramon.