On Wed, 2019-06-05 at 03:38:14 UTC, Alexey Kardashevskiy wrote: > When the firmware does PCI BAR resource allocation, it passes the assigned > addresses and flags (prefetch/64bit/...) via the "reg" property of > a PCI device device tree node so the kernel does not need to do > resource allocation. > > The flags are stored in resource::flags - the lower byte stores > PCI_BASE_ADDRESS_SPACE/etc bits and the other bytes are IORESOURCE_IO/etc. > Some flags from PCI_BASE_ADDRESS_xxx and IORESOURCE_xxx are duplicated, > such as PCI_BASE_ADDRESS_MEM_PREFETCH/PCI_BASE_ADDRESS_MEM_TYPE_64/etc. > When parsing the "reg" property, we copy the prefetch flag but we skip > on PCI_BASE_ADDRESS_MEM_TYPE_64 which leaves the flags out of sync. > > The missing IORESOURCE_MEM_64 flag comes into play under 2 conditions: > 1. we remove PCI_PROBE_ONLY for pseries (by hacking pSeries_setup_arch() > or by passing "/chosen/linux,pci-probe-only"); > 2. we request resource alignment (by passing pci=resource_alignment= > via the kernel cmd line to request PAGE_SIZE alignment or defining > ppc_md.pcibios_default_alignment which returns anything but 0). Note that > the alignment requests are ignored if PCI_PROBE_ONLY is enabled. > > With 1) and 2), the generic PCI code in the kernel unconditionally > decides to: > - reassign the BARs in pci_specified_resource_alignment() (works fine) > - write new BARs to the device - this fails for 64bit BARs as the generic > code looks at IORESOURCE_MEM_64 (not set) and writes only lower 32bits > of the BAR and leaves the upper 32bit unmodified which breaks BAR mapping > in the hypervisor. > > This fixes the issue by copying the flag. This is useful if we want to > enforce certain BAR alignment per platform as handling subpage sized BARs > is proven to cause problems with hotplug (SLOF already aligns BARs to 64k). > > Signed-off-by: Alexey Kardashevskiy <a...@ozlabs.ru> > Reviewed-by: Sam Bobroff <sbobr...@linux.ibm.com> > Reviewed-by: Oliver O'Halloran <ooh...@gmail.com> > Reviewed-by: Shawn Anastasio <sh...@anastas.io>
Applied to powerpc next, thanks. https://git.kernel.org/powerpc/c/df5be5be8735ef2ae80d5ae1f2453cd81a035c4b cheers
