[PATCH v3 04/10] xen/arm: Store p2m type in each page of the guest

[Julien Grall <julien.grall@linaro.org>]

Use the field 'avail' to store the type of the page. Rename it to 'type' for
convenience.
The information stored in this field will be retrieved in a future patch to
change the behaviour when the page is removed.

Also introduce guest_physmap_add_entry to map and set a specific p2m type for
a page.

Signed-off-by: Julien Grall <julien.grall@linaro.org>

---
    Changes in v3:
        - Typo in the commit message
        - Rename 'p2mt' field to 'type'
        - Remove default in switch to let the compiler warns
        - Move BUILD_BUG_ON to patch #3
    Changes in v2:
        - Rename 'avail' field to 'p2mt' in the p2m structure
        - Add BUILD_BUG_ON to check if the enum value will fit in the field
        - Implement grant mapping type
---
 xen/arch/arm/p2m.c         |   56 ++++++++++++++++++++++++++++++++------------
 xen/include/asm-arm/p2m.h  |   18 ++++++++++----
 xen/include/asm-arm/page.h |    2 +-
 3 files changed, 56 insertions(+), 20 deletions(-)

diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
index 691cdfa..3a79927 100644
--- a/xen/arch/arm/p2m.c
+++ b/xen/arch/arm/p2m.c
@@ -128,7 +128,8 @@ int p2m_pod_decrease_reservation(struct domain *d,
     return -ENOSYS;
 }
 
-static lpae_t mfn_to_p2m_entry(unsigned long mfn, unsigned int mattr)
+static lpae_t mfn_to_p2m_entry(unsigned long mfn, unsigned int mattr,
+                               p2m_type_t t)
 {
     paddr_t pa = ((paddr_t) mfn) << PAGE_SHIFT;
     lpae_t e = (lpae_t) {
@@ -136,14 +137,34 @@ static lpae_t mfn_to_p2m_entry(unsigned long mfn, unsigned int mattr)
         .p2m.af = 1,
         .p2m.sh = LPAE_SH_OUTER,
         .p2m.read = 1,
-        .p2m.write = 1,
         .p2m.mattr = mattr,
         .p2m.table = 1,
         .p2m.valid = 1,
+        .p2m.type = t,
     };
 
     BUILD_BUG_ON(p2m_max_real_type > (1 << 4));
 
+    switch (t)
+    {
+    case p2m_grant_map_rw:
+        e.p2m.xn = 1;
+        /* Fallthrough */
+    case p2m_ram_rw:
+    case p2m_mmio_direct:
+    case p2m_map_foreign:
+        e.p2m.write = 1;
+        break;
+
+    case p2m_grant_map_ro:
+        e.p2m.xn = 1;
+        /* Fallthrough */
+    case p2m_invalid:
+    case p2m_ram_ro:
+    default:
+        e.p2m.write = 0;
+    }
+
     ASSERT(!(pa & ~PAGE_MASK));
     ASSERT(!(pa & ~PADDR_MASK));
 
@@ -173,7 +194,7 @@ static int p2m_create_table(struct domain *d,
     clear_page(p);
     unmap_domain_page(p);
 
-    pte = mfn_to_p2m_entry(page_to_mfn(page), MATTR_MEM);
+    pte = mfn_to_p2m_entry(page_to_mfn(page), MATTR_MEM, p2m_invalid);
 
     write_pte(entry, pte);
 
@@ -191,7 +212,8 @@ static int create_p2m_entries(struct domain *d,
                      paddr_t start_gpaddr,
                      paddr_t end_gpaddr,
                      paddr_t maddr,
-                     int mattr)
+                     int mattr,
+                     p2m_type_t t)
 {
     int rc, flush;
     struct p2m_domain *p2m = &d->arch.p2m;
@@ -271,14 +293,15 @@ static int create_p2m_entries(struct domain *d,
                         goto out;
                     }
 
-                    pte = mfn_to_p2m_entry(page_to_mfn(page), mattr);
+                    pte = mfn_to_p2m_entry(page_to_mfn(page), mattr, t);
 
                     write_pte(&third[third_table_offset(addr)], pte);
                 }
                 break;
             case INSERT:
                 {
-                    lpae_t pte = mfn_to_p2m_entry(maddr >> PAGE_SHIFT, mattr);
+                    lpae_t pte = mfn_to_p2m_entry(maddr >> PAGE_SHIFT,
+                                                  mattr, t);
                     write_pte(&third[third_table_offset(addr)], pte);
                     maddr += PAGE_SIZE;
                 }
@@ -313,7 +336,8 @@ int p2m_populate_ram(struct domain *d,
                      paddr_t start,
                      paddr_t end)
 {
-    return create_p2m_entries(d, ALLOCATE, start, end, 0, MATTR_MEM);
+    return create_p2m_entries(d, ALLOCATE, start, end,
+                              0, MATTR_MEM, p2m_ram_rw);
 }
 
 int map_mmio_regions(struct domain *d,
@@ -321,18 +345,20 @@ int map_mmio_regions(struct domain *d,
                      paddr_t end_gaddr,
                      paddr_t maddr)
 {
-    return create_p2m_entries(d, INSERT, start_gaddr, end_gaddr, maddr, MATTR_DEV);
+    return create_p2m_entries(d, INSERT, start_gaddr, end_gaddr,
+                              maddr, MATTR_DEV, p2m_mmio_direct);
 }
 
-int guest_physmap_add_page(struct domain *d,
-                           unsigned long gpfn,
-                           unsigned long mfn,
-                           unsigned int page_order)
+int guest_physmap_add_entry(struct domain *d,
+                            unsigned long gpfn,
+                            unsigned long mfn,
+                            unsigned long page_order,
+                            p2m_type_t t)
 {
     return create_p2m_entries(d, INSERT,
                               pfn_to_paddr(gpfn),
-                              pfn_to_paddr(gpfn + (1<<page_order)),
-                              pfn_to_paddr(mfn), MATTR_MEM);
+                              pfn_to_paddr(gpfn + (1 << page_order)),
+                              pfn_to_paddr(mfn), MATTR_MEM, t);
 }
 
 void guest_physmap_remove_page(struct domain *d,
@@ -342,7 +368,7 @@ void guest_physmap_remove_page(struct domain *d,
     create_p2m_entries(d, REMOVE,
                        pfn_to_paddr(gpfn),
                        pfn_to_paddr(gpfn + (1<<page_order)),
-                       pfn_to_paddr(mfn), MATTR_MEM);
+                       pfn_to_paddr(mfn), MATTR_MEM, p2m_invalid);
 }
 
 int p2m_alloc_table(struct domain *d)
diff --git a/xen/include/asm-arm/p2m.h b/xen/include/asm-arm/p2m.h
index c833c39..dba44fd 100644
--- a/xen/include/asm-arm/p2m.h
+++ b/xen/include/asm-arm/p2m.h
@@ -68,11 +68,21 @@ int p2m_populate_ram(struct domain *d, paddr_t start, paddr_t end);
 int map_mmio_regions(struct domain *d, paddr_t start_gaddr,
                      paddr_t end_gaddr, paddr_t maddr);
 
+int guest_physmap_add_entry(struct domain *d,
+                            unsigned long gfn,
+                            unsigned long mfn,
+                            unsigned long page_order,
+                            p2m_type_t t);
+
 /* Untyped version for RAM only, for compatibility */
-int guest_physmap_add_page(struct domain *d,
-                           unsigned long gfn,
-                           unsigned long mfn,
-                           unsigned int page_order);
+static inline int guest_physmap_add_page(struct domain *d,
+                                         unsigned long gfn,
+                                         unsigned long mfn,
+                                         unsigned int page_order)
+{
+    return guest_physmap_add_entry(d, gfn, mfn, page_order, p2m_ram_rw);
+}
+
 void guest_physmap_remove_page(struct domain *d,
                                unsigned long gpfn,
                                unsigned long mfn, unsigned int page_order);
diff --git a/xen/include/asm-arm/page.h b/xen/include/asm-arm/page.h
index 0625464..670d4e7 100644
--- a/xen/include/asm-arm/page.h
+++ b/xen/include/asm-arm/page.h
@@ -153,7 +153,7 @@ typedef struct {
     unsigned long contig:1;     /* In a block of 16 contiguous entries */
     unsigned long sbz2:1;
     unsigned long xn:1;         /* eXecute-Never */
-    unsigned long avail:4;      /* Ignored by hardware */
+    unsigned long type:4;       /* Ignore by hardware. Used to store p2m types */
 
     unsigned long sbz1:5;
 } __attribute__((__packed__)) lpae_p2m_t;
-- 
1.7.10.4