[PATCH 04/10] [WORKAROUND] xen/arm: Update hwdom's p2m to trap ECAM space

[Oleksandr Andrushchenko <andr2000@gmail.com>]

From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>

Host bridge controller's ECAM space is mapped into Domain-0's p2m,
thus it is not possible to trap the same for vPCI via MMIO handlers.
For this to work we need to unmap those mappings in p2m.

TODO (Julien): It would be best if we avoid the map/unmap operation.
So, maybe we want to introduce another way to avoid the mapping.
Maybe by changing the type of the controller to "PCI_HOSTCONTROLLER"
and checking if this is a PCI hostcontroller avoid the mapping.

Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
---
 xen/arch/arm/domain_build.c         | 10 +++++++++-
 xen/arch/arm/pci/pci-host-common.c  | 15 +++++++++++++++
 xen/arch/arm/pci/pci-host-generic.c | 28 ++++++++++++++++++++++++++++
 xen/include/asm-arm/pci.h           |  2 ++
 4 files changed, 54 insertions(+), 1 deletion(-)

diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index 1f83f9048146..3f696d2a6672 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -2566,7 +2566,15 @@ int __init construct_dom0(struct domain *d)
     if ( rc < 0 )
         return rc;
 
-    return construct_domain(d, &kinfo);
+    rc = construct_domain(d, &kinfo);
+    if ( rc < 0 )
+        return rc;
+
+#ifdef CONFIG_HAS_PCI
+    if ( has_vpci(d) )
+        rc = pci_host_bridge_update_mappings(d);
+#endif
+    return rc;
 }
 
 /*
diff --git a/xen/arch/arm/pci/pci-host-common.c b/xen/arch/arm/pci/pci-host-common.c
index b81184d34980..b6c4d7b636b1 100644
--- a/xen/arch/arm/pci/pci-host-common.c
+++ b/xen/arch/arm/pci/pci-host-common.c
@@ -235,6 +235,21 @@ int pci_host_iterate_bridges(struct domain *d,
     }
     return 0;
 }
+
+static int pci_host_bridge_update_mapping(struct domain *d,
+                                          struct pci_host_bridge *bridge)
+{
+    if ( !bridge->ops->update_mappings )
+        return 0;
+
+    return bridge->ops->update_mappings(d, bridge);
+}
+
+int pci_host_bridge_update_mappings(struct domain *d)
+{
+    return pci_host_iterate_bridges(d, pci_host_bridge_update_mapping);
+}
+
 /*
  * Local variables:
  * mode: C
diff --git a/xen/arch/arm/pci/pci-host-generic.c b/xen/arch/arm/pci/pci-host-generic.c
index 469df3da0116..772c53c881bc 100644
--- a/xen/arch/arm/pci/pci-host-generic.c
+++ b/xen/arch/arm/pci/pci-host-generic.c
@@ -21,6 +21,8 @@
 #include <asm/device.h>
 #include <asm/io.h>
 #include <xen/pci.h>
+#include <xen/sched.h>
+#include <asm/p2m.h>
 #include <asm/pci.h>
 
 /*
@@ -85,6 +87,31 @@ int pci_ecam_config_read(struct pci_host_bridge *bridge, uint32_t sbdf,
     return 0;
 }
 
+/*
+ * TODO: This is called late on domain creation to mangle p2m if needed:
+ * for ECAM host controller for mmio region traps to work for Domain-0
+ * we need to unmap those mappings in p2m.
+ * This is WIP:
+ * julieng: I think it would be best if we avoid the map/unmap operation.
+ * So maybe we want to introduce another way to avoid the mapping.
+ * Maybe by changing the type of the controller to "PCI_HOSTCONTROLLER"
+ * and check if this is a PCI hostcontroller avoid the mapping.
+ */
+static int pci_ecam_update_mappings(struct domain *d,
+                                    struct pci_host_bridge *bridge)
+{
+    struct pci_config_window *cfg = bridge->sysdata;
+    int ret;
+
+    /* Only for control domain which owns this PCI host bridge. */
+    if ( !is_control_domain(d) )
+        return 0;
+
+    ret = unmap_regions_p2mt(d, gaddr_to_gfn(cfg->phys_addr),
+                             cfg->size >> PAGE_SHIFT, INVALID_MFN);
+    return ret;
+}
+
 static int pci_ecam_register_mmio_handler(struct domain *d,
                                           struct pci_host_bridge *bridge,
                                           const struct mmio_handler_ops *ops)
@@ -101,6 +128,7 @@ struct pci_ecam_ops pci_generic_ecam_ops = {
     .pci_ops    = {
         .read                  = pci_ecam_config_read,
         .write                 = pci_ecam_config_write,
+        .update_mappings       = pci_ecam_update_mappings,
         .register_mmio_handler = pci_ecam_register_mmio_handler,
     }
 };
diff --git a/xen/include/asm-arm/pci.h b/xen/include/asm-arm/pci.h
index e3a02429b8d4..d94e8a6628de 100644
--- a/xen/include/asm-arm/pci.h
+++ b/xen/include/asm-arm/pci.h
@@ -65,6 +65,7 @@ struct pci_ops {
                     uint32_t sbdf, int where, int size, u32 *val);
     int (*write)(struct pci_host_bridge *bridge,
                     uint32_t sbdf, int where, int size, u32 val);
+    int (*update_mappings)(struct domain *d, struct pci_host_bridge *bridge);
     int (*register_mmio_handler)(struct domain *d,
                                  struct pci_host_bridge *bridge,
                                  const struct mmio_handler_ops *ops);
@@ -108,6 +109,7 @@ bool dt_pci_parse_bus_range(struct dt_device_node *dev,
 int pci_host_iterate_bridges(struct domain *d,
                              int (*clb)(struct domain *d,
                                         struct pci_host_bridge *bridge));
+int pci_host_bridge_update_mappings(struct domain *d);
 #else   /*!CONFIG_ARM_PCI*/
 struct arch_pci_dev { };
 static inline void  pci_init(void) { }
-- 
2.17.1