[Xen-devel] [PATCH] xen-pciback: relax BAR sizing write value check

["Jan Beulich" <JBeulich@xxxxxxxx>]

Just like done in d2bd05d88d ("xen-pciback: return proper values during
BAR sizing") for the ROM BAR, ordinary ones also shouldn't compare the
written value directly against ~0, but consider the r/o bits at the
bottom (if any).

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 drivers/xen/xen-pciback/conf_space_header.c |   11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

--- 4.14-rc2/drivers/xen/xen-pciback/conf_space_header.c
+++ 4.14-rc2-xen-pciback-BAR-sizing/drivers/xen/xen-pciback/conf_space_header.c
@@ -169,6 +169,9 @@ static int rom_write(struct pci_dev *dev
 static int bar_write(struct pci_dev *dev, int offset, u32 value, void *data)
 {
        struct pci_bar_info *bar = data;
+       unsigned int pos = (offset - PCI_BASE_ADDRESS_0) / 4;
+       const struct resource *res = dev->resource;
+       u32 mask;
 
        if (unlikely(!bar)) {
                pr_warn(DRV_NAME ": driver data not found for %s\n",
@@ -179,7 +182,13 @@ static int bar_write(struct pci_dev *dev
        /* A write to obtain the length must happen as a 32-bit write.
         * This does not (yet) support writing individual bytes
         */
-       if (value == ~0)
+       if (res[pos].flags & IORESOURCE_IO)
+               mask = ~PCI_BASE_ADDRESS_IO_MASK;
+       else if (pos && (res[pos - 1].flags & IORESOURCE_MEM_64))
+               mask = 0;
+       else
+               mask = ~PCI_BASE_ADDRESS_MEM_MASK;
+       if ((value | mask) == ~0U)
                bar->which = 1;
        else {
                u32 tmpval;




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