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

[patchbot@xxxxxxx]

commit cb1ddafdc57305a44e23f781decfdd31dea31189
Author:     Henry Wang <xin.wang2@xxxxxxx>
AuthorDate: Tue Jun 18 17:27:51 2024 -0700
Commit:     Stefano Stabellini <stefano.stabellini@xxxxxxx>
CommitDate: Tue Jun 18 17:27:51 2024 -0700

    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@xxxxxxx>
    Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxx>
    Acked-by: Michal Orzel <michal.orzel@xxxxxxx>
---
 docs/misc/arm/device-tree/booting.txt | 3 +++
 xen/arch/arm/static-shmem.c           | 6 ++++++
 2 files changed, 9 insertions(+)

diff --git a/docs/misc/arm/device-tree/booting.txt 
b/docs/misc/arm/device-tree/booting.txt
index aa0e614864..3a04f5c57f 100644
--- 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 dbb017c7d7..c434b96e62 100644
--- 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;
--
generated by git-patchbot for /home/xen/git/xen.git#staging