xen/arm: Implement p2m_type_t as an enum

Until now, Xen doesn't know the type of the page (ram, foreign page, mmio,...).
Introduce p2m_type_t with basic types:
    - p2m_invalid: Nothing is mapped here
    - p2m_ram_rw: Normal read/write guest RAM
    - p2m_ram_ro: Read-only guest RAM
    - p2m_mmio_direct: Read/write mapping of device memory
    - p2m_map_foreign: RAM page from foreign guest
    - p2m_grant_map_rw: Read/write grant mapping
    - p2m_grant_map_ro: Read-only grant mapping

Signed-off-by: Julien Grall <julien.grall@linaro.org>
Acked-by: Ian Campbell <ian.campbell@citrix.com>

diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
index 74636df5075326bc0a18f0d2e3523a27e70c318b..691cdfab64027cbef76f7f37b65441b555994ecd 100644 (file)
--- a/xen/arch/arm/p2m.c
+++ b/xen/arch/arm/p2m.c
@@ -142,6 +142,8 @@ static lpae_t mfn_to_p2m_entry(unsigned long mfn, unsigned int mattr)
         .p2m.valid = 1,
     };
 
+    BUILD_BUG_ON(p2m_max_real_type > (1 << 4));
+
     ASSERT(!(pa & ~PAGE_MASK));
     ASSERT(!(pa & ~PADDR_MASK));
 

diff --git a/xen/include/asm-arm/p2m.h b/xen/include/asm-arm/p2m.h
index c660820a3debebbd763a02ec0aa693d55f607ca2..bc86a498fafeec3055c55d2c832eabce512020e9 100644 (file)
--- a/xen/include/asm-arm/p2m.h
+++ b/xen/include/asm-arm/p2m.h
@@ -20,6 +20,25 @@ struct p2m_domain {
     uint8_t vmid;
 };
 
+/* List of possible type for each page in the p2m entry.
+ * The number of available bit per page in the pte for this purpose is 4 bits.
+ * So it's possible to only have 16 fields. If we run out of value in the
+ * future, it's possible to use higher value for pseudo-type and don't store
+ * them in the p2m entry.
+ */
+typedef enum {
+    p2m_invalid = 0,    /* Nothing mapped here */
+    p2m_ram_rw,         /* Normal read/write guest RAM */
+    p2m_ram_ro,         /* Read-only; writes are silently dropped */
+    p2m_mmio_direct,    /* Read/write mapping of genuine MMIO area */
+    p2m_map_foreign,    /* Ram pages from foreign domain */
+    p2m_grant_map_rw,   /* Read/write grant mapping */
+    p2m_grant_map_ro,   /* Read-only grant mapping */
+    p2m_max_real_type,  /* Types after this won't be store in the p2m */
+} p2m_type_t;
+
+#define p2m_is_foreign(_t)  ((_t) == p2m_map_foreign)
+
 /* Initialise vmid allocator */
 void p2m_vmid_allocator_init(void);
 
@@ -72,7 +91,6 @@ p2m_pod_decrease_reservation(struct domain *d,
                              unsigned int order);
 
 /* Look up a GFN and take a reference count on the backing page. */
-typedef int p2m_type_t;
 typedef unsigned int p2m_query_t;
 #define P2M_ALLOC    (1u<<0)   /* Populate PoD and paged-out entries */
 #define P2M_UNSHARE  (1u<<1)   /* Break CoW sharing */