From: Jack Lange <jarusl@cs.northwestern.edu>
Date: Fri, 6 Nov 2009 20:13:16 +0000 (-0600)
Subject: added simplistic page table cache
X-Git-Url: http://v3vee.org/palacios/gitweb/gitweb.cgi?p=palacios.git;a=commitdiff_plain;h=fa05269fd639f61ea0c154e6c4bf1daabeb90459

added simplistic page table cache
---

diff --git a/palacios/include/palacios/vmm_shadow_paging.h b/palacios/include/palacios/vmm_shadow_paging.h
index cd0cb7a..d7629a1 100644
--- a/palacios/include/palacios/vmm_shadow_paging.h
+++ b/palacios/include/palacios/vmm_shadow_paging.h
@@ -31,6 +31,9 @@
 
 
 struct shadow_page_state {
+    // ugly optimization hack
+    v3_reg_t prev_guest_cr3;
+
 
     // virtualized control registers
     v3_reg_t guest_cr3;
diff --git a/palacios/src/palacios/vmm_ctrl_regs.c b/palacios/src/palacios/vmm_ctrl_regs.c
index 2b20972..838ce98 100644
--- a/palacios/src/palacios/vmm_ctrl_regs.c
+++ b/palacios/src/palacios/vmm_ctrl_regs.c
@@ -322,14 +322,21 @@ int v3_handle_cr3_write(struct guest_info * info) {
 		struct cr3_32 * guest_cr3 = (struct cr3_32 *)&(info->shdw_pg_state.guest_cr3);
 		*guest_cr3 = *new_cr3;
 	    }
+
+
+
 	    
 	    // If Paging is enabled in the guest then we need to change the shadow page tables
 	    if (info->mem_mode == VIRTUAL_MEM) {
-		if (v3_activate_shadow_pt(info) == -1) {
-		    PrintError("Failed to activate 32 bit shadow page table\n");
-		    return -1;
+		if (info->shdw_pg_state.prev_guest_cr3 != info->shdw_pg_state.guest_cr3) {
+		    if (v3_activate_shadow_pt(info) == -1) {
+			PrintError("Failed to activate 32 bit shadow page table\n");
+			return -1;
+		    }
 		}
 	    }
+
+	    info->shdw_pg_state.prev_guest_cr3 = info->shdw_pg_state.guest_cr3;
 	    
 	    PrintDebug("New Shadow CR3=%p; New Guest CR3=%p\n", 
 		       (void *)(addr_t)(info->ctrl_regs.cr3), 
diff --git a/palacios/src/palacios/vmm_shadow_paging.c b/palacios/src/palacios/vmm_shadow_paging.c
index 0afc383..abe6d88 100644
--- a/palacios/src/palacios/vmm_shadow_paging.c
+++ b/palacios/src/palacios/vmm_shadow_paging.c
@@ -81,6 +81,8 @@ static void telemetry_cb(struct guest_info * info, void * private_data, char * h
 int v3_init_shadow_page_state(struct guest_info * info) {
     struct shadow_page_state * state = &(info->shdw_pg_state);
   
+    state->prev_guest_cr3 = 0;
+
     state->guest_cr3 = 0;
     state->guest_cr0 = 0;
     state->guest_efer.value = 0x0LL;