xen/arm/static-shmem: Static-shmem should be direct-mapped for direct-mapped domains

Currently, users are allowed to map static shared memory in a
non-direct-mapped way for direct-mapped domains. This can lead to
clashing of guest memory spaces. Also, the current extended region
finding logic only removes the host physical addresses of the
static shared memory areas for direct-mapped domains, which may be
inconsistent with the guest memory map if users map the static
shared memory in a non-direct-mapped way. This will lead to incorrect
extended region calculation results.

To make things easier, add restriction that static shared memory
should also be direct-mapped for direct-mapped domains. Check the
host physical address to be matched with guest physical address when
parsing the device tree. Document this restriction in the doc.

Signed-off-by: Henry Wang <xin.wang2@amd.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@amd.com>
Acked-by: Michal Orzel <michal.orzel@amd.com>

diff --git a/docs/misc/arm/device-tree/booting.txt b/docs/misc/arm/device-tree/booting.txt
index aa0e6148642f45b0b826fd506952069d80094b00..3a04f5c57f518a253e29636f87a43ab5b4fa1ee5 100644 (file)
--- a/docs/misc/arm/device-tree/booting.txt
+++ b/docs/misc/arm/device-tree/booting.txt
@@ -607,6 +607,9 @@ communication.
     shared memory region in host physical address space, a size, and a guest
     physical address, as the target address of the mapping.
     e.g. xen,shared-mem = < [host physical address] [guest address] [size] >;
+    Note that if a domain is direct-mapped, i.e. the Dom0 and the Dom0less
+    DomUs with `direct-map` device tree property, the static shared memory
+    should also be direct-mapped (host physical address == guest address).
 
     It shall also meet the following criteria:
     1) If the SHM ID matches with an existing region, the address range of the

diff --git a/xen/arch/arm/static-shmem.c b/xen/arch/arm/static-shmem.c
index dbb017c7d76e69a5c69752208cac197a10f2e248..c434b96e620425bd527fda0e9de34f52f1b7a3f6 100644 (file)
--- a/xen/arch/arm/static-shmem.c
+++ b/xen/arch/arm/static-shmem.c
@@ -324,6 +324,12 @@ int __init process_shm(struct domain *d, struct kernel_info *kinfo,
             printk("%pd: static shared memory bank not found: '%s'", d, shm_id);
             return -ENOENT;
         }
+        if ( is_domain_direct_mapped(d) && (pbase != gbase) )
+        {
+            printk("%pd: physical address 0x%"PRIpaddr" and guest address 0x%"PRIpaddr" are not direct-mapped.\n",
+                   d, pbase, gbase);
+            return -EINVAL;
+        }
 
         pbase = boot_shm_bank->start;
         psize = boot_shm_bank->size;