[PATCH v4 2/2] xen/pci: replace call to is_memory_hole to pci_check_bar

[Rahul Singh <rahul.singh@xxxxxxx>]

is_memory_hole was implemented for x86 and not for ARM when introduced.
Replace is_memory_hole call to pci_check_bar as function should check
if device BAR is in defined memory range. Also, add an implementation
for ARM which is required for PCI passthrough.

On x86, pci_check_bar will call is_memory_hole which will check if BAR
is not overlapping with any memory region defined in the memory map.

On ARM, pci_check_bar will go through the host bridge ranges and check
if the BAR is in the range of defined ranges.

Signed-off-by: Rahul Singh <rahul.singh@xxxxxxx>
---
Changes in v4:
 - check "s <= e" before callback
 - Add TODO comment for revisiting the function pci_check_bar() when
   ACPI PCI passthrough support is added.
 - Not Added the Jan Acked-by as patch is modified.
Changes in v3:
 - fix minor comments
---
 xen/arch/arm/include/asm/pci.h     |  2 ++
 xen/arch/arm/pci/pci-host-common.c | 49 ++++++++++++++++++++++++++++++
 xen/arch/x86/include/asm/pci.h     | 10 ++++++
 xen/drivers/passthrough/pci.c      |  8 ++---
 4 files changed, 65 insertions(+), 4 deletions(-)

diff --git a/xen/arch/arm/include/asm/pci.h b/xen/arch/arm/include/asm/pci.h
index 80a2431804..8cb46f6b71 100644
--- a/xen/arch/arm/include/asm/pci.h
+++ b/xen/arch/arm/include/asm/pci.h
@@ -126,6 +126,8 @@ int pci_host_iterate_bridges_and_count(struct domain *d,
 
 int pci_host_bridge_mappings(struct domain *d);
 
+bool pci_check_bar(const struct pci_dev *pdev, mfn_t start, mfn_t end);
+
 #else   /*!CONFIG_HAS_PCI*/
 
 struct arch_pci_dev { };
diff --git a/xen/arch/arm/pci/pci-host-common.c 
b/xen/arch/arm/pci/pci-host-common.c
index 89ef30028e..13d419aa45 100644
--- a/xen/arch/arm/pci/pci-host-common.c
+++ b/xen/arch/arm/pci/pci-host-common.c
@@ -24,6 +24,16 @@
 
 #include <asm/setup.h>
 
+/*
+ * struct to hold pci device bar.
+ */
+struct pdev_bar_check
+{
+    unsigned long start;
+    unsigned long end;
+    bool is_valid;
+};
+
 /*
  * List for all the pci host bridges.
  */
@@ -363,6 +373,45 @@ int __init pci_host_bridge_mappings(struct domain *d)
     return 0;
 }
 
+static int is_bar_valid(const struct dt_device_node *dev,
+                        uint64_t addr, uint64_t len, void *data)
+{
+    struct pdev_bar_check *bar_data = data;
+    unsigned long s = bar_data->start;
+    unsigned long e = bar_data->end;
+
+    if ( (s >= PFN_DOWN(addr)) && (e <= PFN_UP(addr + len - 1)) )
+        bar_data->is_valid =  true;
+
+    return 0;
+}
+
+/* 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;
+    unsigned long s = mfn_x(start);
+    unsigned long e = mfn_x(end);
+    struct pdev_bar_check bar_data =  {
+        .start = s,
+        .end = e,
+        .is_valid = false
+    };
+
+    if ( s >= e )
+        return false;
+
+    dt_node = pci_find_host_bridge_node(pdev);
+    if ( !dt_node )
+        return false;
+
+    ret = dt_for_each_range(dt_node, &is_bar_valid, &bar_data);
+    if ( ret < 0 )
+        return false;
+
+    return bar_data.is_valid;
+}
 /*
  * Local variables:
  * mode: C
diff --git a/xen/arch/x86/include/asm/pci.h b/xen/arch/x86/include/asm/pci.h
index c8e1a9ecdb..f4a58c8acf 100644
--- a/xen/arch/x86/include/asm/pci.h
+++ b/xen/arch/x86/include/asm/pci.h
@@ -57,4 +57,14 @@ static always_inline bool is_pci_passthrough_enabled(void)
 
 void arch_pci_init_pdev(struct pci_dev *pdev);
 
+static inline bool pci_check_bar(const struct pci_dev *pdev,
+                                 mfn_t start, mfn_t end)
+{
+    /*
+     * Check if BAR is not overlapping with any memory region defined
+     * in the memory map.
+     */
+    return is_memory_hole(start, end);
+}
+
 #endif /* __X86_PCI_H__ */
diff --git a/xen/drivers/passthrough/pci.c b/xen/drivers/passthrough/pci.c
index cdaf5c247f..149f68bb6e 100644
--- a/xen/drivers/passthrough/pci.c
+++ b/xen/drivers/passthrough/pci.c
@@ -304,8 +304,8 @@ static void check_pdev(const struct pci_dev *pdev)
         if ( rc < 0 )
             /* Unable to size, better leave memory decoding disabled. */
             return;
-        if ( size && !is_memory_hole(maddr_to_mfn(addr),
-                                     maddr_to_mfn(addr + size - 1)) )
+        if ( size && !pci_check_bar(pdev, maddr_to_mfn(addr),
+                                    maddr_to_mfn(addr + size - 1)) )
         {
             /*
              * Return without enabling memory decoding if BAR position is not
@@ -331,8 +331,8 @@ static void check_pdev(const struct pci_dev *pdev)
 
         if ( rc < 0 )
             return;
-        if ( size && !is_memory_hole(maddr_to_mfn(addr),
-                                     maddr_to_mfn(addr + size - 1)) )
+        if ( size && !pci_check_bar(pdev, maddr_to_mfn(addr),
+                                    maddr_to_mfn(addr + size - 1)) )
         {
             printk(warn, &pdev->sbdf, "ROM ", PFN_DOWN(addr),
                    PFN_DOWN(addr + size - 1));
-- 
2.25.1