On Fri, Sep 27, 2024 at 08:48:28AM +0200, Andrea della Porta wrote: > On 15:16 Thu 05 Sep , Bjorn Helgaas wrote: > > On Thu, Sep 05, 2024 at 06:43:35PM +0200, Andrea della Porta wrote: > > > On 17:26 Tue 03 Sep , Bjorn Helgaas wrote: > > > > On Mon, Aug 26, 2024 at 09:51:02PM +0200, Andrea della Porta wrote: > > > > > On 10:24 Wed 21 Aug , Bjorn Helgaas wrote: > > > > > > On Tue, Aug 20, 2024 at 04:36:05PM +0200, Andrea della Porta wrote: > > > > > > > The of_pci_set_address() function parses devicetree PCI range > > > > > > > specifier assuming the address is 'sanitized' at the origin, > > > > > > > i.e. without checking whether the incoming address is 32 or 64 > > > > > > > bit has specified in the flags. In this way an address with no > > > > > > > OF_PCI_ADDR_SPACE_MEM64 set in the flags could leak through and > > > > > > > the upper 32 bits of the address will be set too, and this > > > > > > > violates the PCI specs stating that in 32 bit address the upper > > > > > > > bit should be zero. > > > > > > > > > > I don't understand this code, so I'm probably missing something. It > > > > > > looks like the interesting path here is: > > > > > > > > > > > > of_pci_prop_ranges > > > > > > res = &pdev->resource[...]; > > > > > > for (j = 0; j < num; j++) { > > > > > > val64 = res[j].start; > > > > > > of_pci_set_address(..., val64, 0, flags, false); > > > > > > + if (OF_PCI_ADDR_SPACE_MEM64) > > > > > > + prop[1] = upper_32_bits(val64); > > > > > > + else > > > > > > + prop[1] = 0; > > > ... > > > > However, the CPU physical address space and the PCI bus address are > > > > not the same. Generic code paths should account for that different by > > > > applying an offset (the offset will be zero on many platforms where > > > > CPU and PCI bus addresses *look* the same). > > > > > > > > So a generic code path like of_pci_prop_ranges() that basically copies > > > > a CPU physical address to a PCI bus address looks broken to me. > > > > > > Hmmm, I'd say that a translation from one bus type to the other is > > > going on nonetheless, and this is done in the current upstream function > > > as well. This patch of course does not add the translation (which is > > > already in place), just to do it avoiding generating inconsistent address. > > > > I think I was looking at this backwards. I assumed we were *parsing" > > a "ranges" property, but I think in fact we're *building* a "ranges" > > property to describe an existing PCI device (either a PCI-to-PCI > > bridge or an endpoint). For such devices there is no address > > translation. > > > > Any address translation would only occur at a PCI host bridge that has > > CPU address space on the upstream side and PCI address space on the > > downstream side. > > > > Since (IIUC), we're building "ranges" for a device in the interior of > > a PCI hierarchy where address translation doesn't happen, I think both > > the parent and child addresses in "ranges" should be in the PCI > > address space. > > > > But right now, I think they're both in the CPU address space, and we > > basically do this: > > > > of_pci_prop_ranges(struct pci_dev *pdev, ...) > > res = &pdev->resource[...]; > > for (j = 0; j < num; j++) { # iterate through BARs or windows > > val64 = res[j].start; # CPU physical address > > # <convert to PCI address space> > > of_pci_set_address(..., rp[i].parent_addr, val64, ...) > > rp[i].parent_addr = val64 > > if (pci_is_bridge(pdev)) > > memcpy(rp[i].child_addr, rp[i].parent_addr) > > else > > rp[i].child_addr[0] = j # child addr unset/unused > > > > Here "res" is a PCI BAR or bridge window, and it contains CPU physical > > addresses, so "val64" is a CPU physical address. It looks to me like > > we should convert to a PCI bus address at the point noted above, based > > on any translation described by the PCI host bridge. That *should* > > naturally result in a 32-bit value if OF_PCI_ADDR_SPACE_MEM64 is not > > set. > > That's exactly the point, except that right now a 64 bit address would > "unnaturally" pass through even if OF_PCI_ADDR_SPACE_MEM64 is not set. > Hence the purpose of this patch.