[Xen-devel] [PATCH v4 2/7] xen/arm: p2m: Add support for normal non-cacheable memory

["Edgar E. Iglesias" <edgar.iglesias@xxxxxxxxx>]

From: "Edgar E. Iglesias" <edgar.iglesias@xxxxxxxxxx>

Add support for describing normal non-cacheable memory.

Signed-off-by: Edgar E. Iglesias <edgar.iglesias@xxxxxxxxxx>
---
 xen/arch/arm/p2m.c         | 19 +++++++++++++++++++
 xen/include/asm-arm/p2m.h  |  1 +
 xen/include/asm-arm/page.h |  1 +
 3 files changed, 21 insertions(+)

diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
index c3b1233..9912658 100644
--- a/xen/arch/arm/p2m.c
+++ b/xen/arch/arm/p2m.c
@@ -296,6 +296,7 @@ static void p2m_set_permission(lpae_t *e, p2m_type_t t, 
p2m_access_t a)
     case p2m_map_foreign:
     case p2m_grant_map_rw:
     case p2m_mmio_direct_dev:
+    case p2m_mmio_direct_nc:
     case p2m_mmio_direct_c:
         e->p2m.xn = 1;
         e->p2m.write = 1;
@@ -376,6 +377,24 @@ static lpae_t mfn_to_p2m_entry(mfn_t mfn, p2m_type_t t, 
p2m_access_t a)
         e.p2m.sh = LPAE_SH_OUTER;
         break;
 
+    /*
+     * ARM ARM: Overlaying the shareability attribute (DDI
+     * 0406C.b B3-1376 to 1377)
+     *
+     * A memory region with a resultant memory type attribute of Normal,
+     * and a resultant cacheability attribute of Inner Non-cacheable,
+     * Outer Non-cacheable, must have a resultant shareability attribute
+     * of Outer Shareable, otherwise shareability is UNPREDICTABLE.
+     *
+     * On ARMv8 shareability is ignored and explicitly treated as Outer
+     * Shareable for Normal Inner Non_cacheable, Outer Non-cacheable.
+     * See the note for table D4-40, in page 1788 of the ARM DDI 0487A.j.
+     */
+    case p2m_mmio_direct_nc:
+        e.p2m.mattr = MATTR_MEM_NC;
+        e.p2m.sh = LPAE_SH_OUTER;
+        break;
+
     default:
         e.p2m.mattr = MATTR_MEM;
         e.p2m.sh = LPAE_SH_INNER;
diff --git a/xen/include/asm-arm/p2m.h b/xen/include/asm-arm/p2m.h
index b342122..9708fdc 100644
--- a/xen/include/asm-arm/p2m.h
+++ b/xen/include/asm-arm/p2m.h
@@ -92,6 +92,7 @@ typedef enum {
     p2m_ram_rw,         /* Normal read/write guest RAM */
     p2m_ram_ro,         /* Read-only; writes are silently dropped */
     p2m_mmio_direct_dev,/* Read/write mapping of genuine Device MMIO area */
+    p2m_mmio_direct_nc, /* Read/write mapping of genuine MMIO area 
non-cacheable */
     p2m_mmio_direct_c,  /* Read/write mapping of genuine MMIO area cacheable */
     p2m_map_foreign,    /* Ram pages from foreign domain */
     p2m_grant_map_rw,   /* Read/write grant mapping */
diff --git a/xen/include/asm-arm/page.h b/xen/include/asm-arm/page.h
index 015ed63..f50fe60 100644
--- a/xen/include/asm-arm/page.h
+++ b/xen/include/asm-arm/page.h
@@ -84,6 +84,7 @@
  *
  */
 #define MATTR_DEV     0x1
+#define MATTR_MEM_NC  0x5
 #define MATTR_MEM     0xf
 
 /* Flags for get_page_from_gva, gvirt_to_maddr etc */
-- 
2.7.4


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