[xen master] xen/arm: pci: fix check in pci_check_bar()

[patchbot@xxxxxxx]

commit 11961f0a6700fb62edb17930fcf6c3f5453c133b
Author:     Stewart Hildebrand <stewart.hildebrand@xxxxxxx>
AuthorDate: Wed Jul 12 09:52:21 2023 -0400
Commit:     Julien Grall <jgrall@xxxxxxxxxx>
CommitDate: Thu Jul 13 19:19:25 2023 +0100

    xen/arm: pci: fix check in pci_check_bar()
    
    When mapping BARs for vPCI, it's valid for a BAR mfn_t start to equal the 
BAR
    mfn_t end (i.e. start == end) since end is inclusive. However, 
pci_check_bar()
    currently returns false in this case, which results in Xen not mapping the 
BAR
    in the guest 2nd stage page tables. In this example boot log, Linux has 
mapped
    the BARs in the 1st stage, but since Xen did not map them in the 2nd stage,
    Linux encounters a data abort and panics:
    
    [    2.593300] pci 0000:00:00.0: BAR 0: assigned [mem 0x50008000-0x50008fff]
    [    2.593682] pci 0000:00:00.0: BAR 2: assigned [mem 0x50009000-0x50009fff]
    [    2.594066] pci 0000:00:00.0: BAR 4: assigned [mem 0x5000a000-0x5000afff]
    ...
    [    2.810502] virtio-pci 0000:00:00.0: enabling device (0000 -> 0002)
    (XEN) 0000:00:00.0: not mapping BAR [50008, 50008] invalid position
    (XEN) 0000:00:00.0: not mapping BAR [50009, 50009] invalid position
    (XEN) 0000:00:00.0: not mapping BAR [5000a, 5000a] invalid position
    [    2.817502] virtio-pci 0000:00:00.0: virtio_pci: leaving for legacy 
driver
    [    2.817853] virtio-pci 0000:00:00.0: enabling bus mastering
    (XEN) arch/arm/traps.c:1992:d0v0 HSR=0x00000093010045 pc=0xffff8000089507d4 
gva=0xffff80000c46d012 gpa=0x00000050008012
    [    2.818397] Unable to handle kernel ttbr address size fault at virtual 
address ffff80000c46d012
    ...
    
    Adjust the end physical address e to account for the full page when 
converting
    from mfn, at which point s and e cannot be equal, so drop the equality 
check in
    the condition.
    
    Note that adjusting e to account for the full page also increases the 
accuracy
    of the subsequent is_bar_valid check.
    
    Fixes: cc80e2bab0d0 ("xen/pci: replace call to is_memory_hole to 
pci_check_bar")
    Signed-off-by: Stewart Hildebrand <stewart.hildebrand@xxxxxxx>
    Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
    Reviewed-by: Rahul Singh <rahul.singh@xxxxxxx>
    Tested-by: Rahul Singh <rahul.singh@xxxxxxx>
    Acked-by: Julien Grall <jgrall@xxxxxxxxxx>
---
 xen/arch/arm/pci/pci-host-common.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/xen/arch/arm/pci/pci-host-common.c 
b/xen/arch/arm/pci/pci-host-common.c
index 7cdfc89e52..c0faf0f436 100644
--- a/xen/arch/arm/pci/pci-host-common.c
+++ b/xen/arch/arm/pci/pci-host-common.c
@@ -393,20 +393,24 @@ static int is_bar_valid(const struct dt_device_node *dev,
     return 0;
 }
 
-/* TODO: Revisit this function when ACPI PCI passthrough support is added. */
+/*
+ * The MFN range [start, end] is inclusive.
+ *
+ * TODO: Revisit this function when ACPI PCI passthrough support is added.
+ */
 bool pci_check_bar(const struct pci_dev *pdev, mfn_t start, mfn_t end)
 {
     int ret;
     const struct dt_device_node *dt_node;
     paddr_t s = mfn_to_maddr(start);
-    paddr_t e = mfn_to_maddr(end);
+    paddr_t e = mfn_to_maddr(mfn_add(end, 1)) - 1; /* inclusive */
     struct pdev_bar_check bar_data =  {
         .start = s,
         .end = e,
         .is_valid = false
     };
 
-    if ( s >= e )
+    if ( s > e )
         return false;
 
     dt_node = pci_find_host_bridge_node(pdev);
--
generated by git-patchbot for /home/xen/git/xen.git#master