[xen staging] xen/arm: Allow a platform to override the DMA width

[patchbot@xxxxxxx]

commit b92223aeedc5cf1cd2882a7b769865d652cf8b06
Author:     Julien Grall <jgrall@xxxxxxxxxx>
AuthorDate: Sat May 16 11:41:16 2020 +0100
Commit:     Julien Grall <jgrall@xxxxxxxxxx>
CommitDate: Sun May 24 14:59:46 2020 +0100

    xen/arm: Allow a platform to override the DMA width
    
    At the moment, Xen is assuming that all the devices are at least 32-bit
    DMA capable. However, some SoC have devices that may be able to access
    a much restricted range. For instance, the RPI has devices that can
    only access the first 1GB of RAM.
    
    The structure platform_desc is now extended to allow a platform to
    override the DMA width. The new is used to implement
    arch_get_dma_bit_size().
    
    The prototype is now moved in asm-arm/mm.h as the function is not NUMA
    specific. The implementation is done in platform.c so we don't have to
    include platform.h everywhere. This should be fine as the function is
    not expected to be called in hotpath.
    
    Signed-off-by: Julien Grall <jgrall@xxxxxxxxxx>
    Reviewed-by: Volodymyr Babchuk <volodymyr_babchuk@xxxxxxxx>
    Tested-by: Corey Minyard <cminyard@xxxxxxxxxx>
    Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
---
 xen/arch/arm/platform.c        | 5 +++++
 xen/include/asm-arm/mm.h       | 2 ++
 xen/include/asm-arm/numa.h     | 5 -----
 xen/include/asm-arm/platform.h | 2 ++
 4 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/xen/arch/arm/platform.c b/xen/arch/arm/platform.c
index 8eb0b6e57a..4db5bbb4c5 100644
--- a/xen/arch/arm/platform.c
+++ b/xen/arch/arm/platform.c
@@ -155,6 +155,11 @@ bool platform_device_is_blacklisted(const struct 
dt_device_node *node)
     return (dt_match_node(blacklist, node) != NULL);
 }
 
+unsigned int arch_get_dma_bitsize(void)
+{
+    return ( platform && platform->dma_bitsize ) ? platform->dma_bitsize : 32;
+}
+
 /*
  * Local variables:
  * mode: C
diff --git a/xen/include/asm-arm/mm.h b/xen/include/asm-arm/mm.h
index 7df91280bc..f8ba49b118 100644
--- a/xen/include/asm-arm/mm.h
+++ b/xen/include/asm-arm/mm.h
@@ -366,6 +366,8 @@ int arch_acquire_resource(struct domain *d, unsigned int 
type, unsigned int id,
     return -EOPNOTSUPP;
 }
 
+unsigned int arch_get_dma_bitsize(void);
+
 #endif /*  __ARCH_ARM_MM__ */
 /*
  * Local variables:
diff --git a/xen/include/asm-arm/numa.h b/xen/include/asm-arm/numa.h
index 490d1f31aa..31a6de4e23 100644
--- a/xen/include/asm-arm/numa.h
+++ b/xen/include/asm-arm/numa.h
@@ -25,11 +25,6 @@ extern mfn_t first_valid_mfn;
 #define node_start_pfn(nid) (mfn_x(first_valid_mfn))
 #define __node_distance(a, b) (20)
 
-static inline unsigned int arch_get_dma_bitsize(void)
-{
-    return 32;
-}
-
 #endif /* __ARCH_ARM_NUMA_H */
 /*
  * Local variables:
diff --git a/xen/include/asm-arm/platform.h b/xen/include/asm-arm/platform.h
index ed4d30a1be..997eb25216 100644
--- a/xen/include/asm-arm/platform.h
+++ b/xen/include/asm-arm/platform.h
@@ -38,6 +38,8 @@ struct platform_desc {
      * List of devices which must not pass-through to a guest
      */
     const struct dt_device_match *blacklist_dev;
+    /* Override the DMA width (32-bit by default). */
+    unsigned int dma_bitsize;
 };
 
 /*
--
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