Cleanup and sanity-checking of unintentional integer overflow, unsigned/zero comparis...

[palacios.git] / palacios / src / palacios / vmx_msr.c

diff --git a/palacios/src/palacios/vmx_msr.c b/palacios/src/palacios/vmx_msr.c
index f470c37..18bb3ee 100644 (file)
--- a/palacios/src/palacios/vmx_msr.c
+++ b/palacios/src/palacios/vmx_msr.c
@@ -31,12 +31,13 @@
 
 static int get_bitmap_index(uint_t msr)
 {
+    // unsigned comparison with 0 here for clarity
     if( (msr >= LOW_MSR_START) && msr <= LOW_MSR_END) {
         return LOW_MSR_INDEX + msr;
     } else if (( msr >= HIGH_MSR_START ) && (msr <= HIGH_MSR_END)) {
         return (HIGH_MSR_INDEX * 8) + (msr - HIGH_MSR_START);
     } else {
-        PrintError("MSR out of range: 0x%x\n", msr);
+        PrintError(VM_NONE, VCORE_NONE,  "MSR out of range: 0x%x\n", msr);
         return -1;
     }
 }
@@ -51,6 +52,12 @@ static int update_map(struct v3_vm_info * vm, uint_t msr, int hook_reads, int ho
     uint8_t write_val = (hook_writes) ? 0x1 : 0x0;
     uint8_t * bitmap = (uint8_t *)(vm->msr_map.arch_data);
 
+    if (index == -1) {
+       //      0rintError("Error updating MSR Map failed bitmap index for (0x%x)\n", msr);
+       // MSRs not in the bitmap covered range will always trigger exits, so we don't need to worry about them here.
+       return 0;
+    }
+
     *(bitmap + major) &= ~(mask << minor);
     *(bitmap + major) |= (read_val << minor);
 
@@ -61,11 +68,18 @@ static int update_map(struct v3_vm_info * vm, uint_t msr, int hook_reads, int ho
 }
 
 int v3_init_vmx_msr_map(struct v3_vm_info * vm) {
+    void *temp;
+
     struct v3_msr_map * msr_map = &(vm->msr_map);
 
     msr_map->update_map = update_map;
     
-    msr_map->arch_data = V3_VAddr(V3_AllocPages(1));
+    temp = V3_AllocPages(1); // need not be shadow-safe, not exposed to guest
+    if (!temp) { 
+        PrintError(vm, VCORE_NONE, "Cannot allocat MSR bitmap\n");
+       return -1;
+    }
+    msr_map->arch_data = V3_VAddr(temp);
     memset(msr_map->arch_data, 0xff, PAGE_SIZE_4KB);
     
     v3_refresh_msr_map(vm);