[Xen-devel] [PATCH v1 1/2] x86: add p2m_ram_wp

[Wei Ye <wei.ye@xxxxxxxxx>]

Add a new p2m type p2m_ram_wp. Page of p2m_ram_wp is read only, and
write will go to the device model for emulation.

Signed-off-by: Wei Ye <wei.ye@xxxxxxxxx>
---
 xen/arch/x86/hvm/hvm.c    |    8 +++++++-
 xen/arch/x86/mm/p2m-ept.c |    1 +
 xen/include/asm-x86/p2m.h |    8 +++++++-
 3 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 17ff011..0f20b62 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -2738,7 +2738,8 @@ int hvm_hap_nested_page_fault(paddr_t gpa,
      * If this GFN is emulated MMIO or marked as read-only, pass the fault
      * to the mmio handler.
      */
-    if ( (p2mt == p2m_mmio_dm) || 
+    if ( (p2mt == p2m_mmio_dm) ||
+         (p2mt == p2m_ram_wp) || 
          (access_w && (p2mt == p2m_ram_ro)) )
     {
         put_gfn(p2m->domain, gfn);
@@ -3829,6 +3830,11 @@ static enum hvm_copy_result __hvm_copy(
             put_page(page);
             return HVMCOPY_unhandleable;
         }
+        if ( p2m_is_wp_ram(p2mt) )
+        {
+            put_page(page);
+            return HVMCOPY_bad_gfn_to_mfn;
+        }
 
         p = (char *)__map_domain_page(page) + (addr & ~PAGE_MASK);
 
diff --git a/xen/arch/x86/mm/p2m-ept.c b/xen/arch/x86/mm/p2m-ept.c
index 15c6e83..1b4a83e 100644
--- a/xen/arch/x86/mm/p2m-ept.c
+++ b/xen/arch/x86/mm/p2m-ept.c
@@ -125,6 +125,7 @@ static void ept_p2m_type_to_flags(ept_entry_t *entry, 
p2m_type_t type, p2m_acces
                                                     entry->mfn);
             break;
         case p2m_ram_logdirty:
+        case p2m_ram_wp:
         case p2m_ram_ro:
         case p2m_ram_shared:
             entry->r = entry->x = 1;
diff --git a/xen/include/asm-x86/p2m.h b/xen/include/asm-x86/p2m.h
index 0ddbadb..bbec847 100644
--- a/xen/include/asm-x86/p2m.h
+++ b/xen/include/asm-x86/p2m.h
@@ -71,6 +71,7 @@ typedef enum {
     p2m_ram_shared = 12,          /* Shared or sharable memory */
     p2m_ram_broken = 13,          /* Broken page, access cause domain crash */
     p2m_map_foreign  = 14,        /* ram pages from foreign domain */
+    p2m_ram_wp = 15,              /* Read-only; write go to the device model */
 } p2m_type_t;
 
 /*
@@ -116,7 +117,8 @@ typedef unsigned int p2m_query_t;
                        | p2m_to_mask(p2m_ram_paging_out)      \
                        | p2m_to_mask(p2m_ram_paged)           \
                        | p2m_to_mask(p2m_ram_paging_in)       \
-                       | p2m_to_mask(p2m_ram_shared))
+                       | p2m_to_mask(p2m_ram_shared)          \
+                       | p2m_to_mask(p2m_ram_wp))
 
 /* Types that represent a physmap hole that is ok to replace with a shared
  * entry */
@@ -167,6 +169,9 @@ typedef unsigned int p2m_query_t;
  * and must not be touched. */
 #define P2M_BROKEN_TYPES (p2m_to_mask(p2m_ram_broken))
 
+/* Write protection types */
+#define P2M_WP_TYPES (p2m_to_mask(p2m_ram_wp))
+
 /* Useful predicates */
 #define p2m_is_ram(_t) (p2m_to_mask(_t) & P2M_RAM_TYPES)
 #define p2m_is_hole(_t) (p2m_to_mask(_t) & P2M_HOLE_TYPES)
@@ -191,6 +196,7 @@ typedef unsigned int p2m_query_t;
 #define p2m_is_any_ram(_t)  (p2m_to_mask(_t) &                   \
                              (P2M_RAM_TYPES | P2M_GRANT_TYPES |  \
                               p2m_to_mask(p2m_map_foreign)))
+#define p2m_is_wp_ram(_t)   (p2m_to_mask(_t) & P2M_WP_TYPES)
 
 /* Per-p2m-table state */
 struct p2m_domain {
-- 
1.7.9.5


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