[Xen-devel] [PATCH V3 32/41] xen/arm: WORKAROUND 1:1 memory mapping for dom0

[Julien Grall <julien.grall@xxxxxxxxxx>]

Currently xen doesn't implement SYS MMU. When a device will talk with dom0
with DMA request the domain will use GFN instead of MFN.
For instance on the arndale board, without this patch the network doesn't
work.

The 1:1 mapping is a workaround and MUST be remove as soon as a SYS MMU is
implemented in XEN.

Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>

Changes in v2:
    - Add quirk in platform code to only enable 1:1 mapping if the
    board really need it to run (ie: SYS MMU is not yet implemented in Xen).
---
 xen/arch/arm/domain_build.c    |   41 ++++++++++++++++++++++++++++++++++++++++
 xen/include/asm-arm/platform.h |    6 ++++++
 2 files changed, 47 insertions(+)

diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index 75c3006..8369099 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -62,6 +62,43 @@ struct vcpu *__init alloc_dom0_vcpu0(void)
     return alloc_vcpu(dom0, 0, 0);
 }
 
+static int set_memory_reg_11(struct domain *d, struct kernel_info *kinfo,
+                             const void *fdt, const u32 *cell, int len,
+                             int address_cells, int size_cells, u32 *new_cell)
+{
+    int reg_size = (address_cells + size_cells) * sizeof(*cell);
+    paddr_t start;
+    paddr_t size;
+    struct page_info *pg;
+    unsigned int order = get_order_from_bytes(dom0_mem);
+    int res;
+    paddr_t spfn;
+
+    pg = alloc_domheap_pages(d, order, 0);
+    if ( !pg )
+        panic("Failed to allocate contiguous memory for dom0\n");
+
+    spfn = page_to_mfn(pg);
+    start = spfn << PAGE_SHIFT;
+    size = (1 << order) << PAGE_SHIFT;
+
+    // 1:1 mapping
+    printk("Populate P2M %#"PRIx64"->%#"PRIx64" (1:1 mapping for dom0)\n",
+           start, start + size);
+    res = guest_physmap_add_page(d, spfn, spfn, order);
+
+    if ( res )
+        panic("Unable to add pages in DOM0: %d\n", res);
+
+    device_tree_set_reg(&new_cell, address_cells, size_cells, start, size);
+
+    kinfo->mem.bank[0].start = start;
+    kinfo->mem.bank[0].size = size;
+    kinfo->mem.nr_banks = 1;
+
+    return reg_size;
+}
+
 static int set_memory_reg(struct domain *d, struct kernel_info *kinfo,
                           const void *fdt, const u32 *cell, int len,
                           int address_cells, int size_cells, u32 *new_cell)
@@ -71,6 +108,10 @@ static int set_memory_reg(struct domain *d, struct 
kernel_info *kinfo,
     u64 start;
     u64 size;
 
+    if ( platform_has_quirk(PLATFORM_QUIRK_DOM0_MAPPING_11) )
+        return set_memory_reg_11(d, kinfo, fdt, cell, len, address_cells,
+                                 size_cells, new_cell);
+
     while ( kinfo->unassigned_mem > 0 && l + reg_size <= len
             && kinfo->mem.nr_banks < NR_MEM_BANKS )
     {
diff --git a/xen/include/asm-arm/platform.h b/xen/include/asm-arm/platform.h
index e116265..f460e9c 100644
--- a/xen/include/asm-arm/platform.h
+++ b/xen/include/asm-arm/platform.h
@@ -28,6 +28,12 @@ struct platform_desc {
     uint32_t (*quirks)(void);
 };
 
+/*
+ * Quirk to map dom0 memory in 1:1
+ * Usefull on platform where System MMU is not yet implemented
+ */
+#define PLATFORM_QUIRK_DOM0_MAPPING_11 (1 << 0)
+
 int __init platform_init(void);
 int __init platform_init_time(void);
 int __init platform_specific_mapping(struct domain *d);
-- 
1.7.10.4


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