xen-access: write_ctrlreg_c4 test

Add test for write_ctrlreg event handling.

Signed-off-by: Petre Pircalabu <ppircalabu@bitdefender.com>
Acked-by: Tamas K Lengyel <tamas@tklengyel.com>

tools/tests/xen-access/xen-access.c

@@ -57,6 +57,13 @@
 #define X86_TRAP_DEBUG  1
 #define X86_TRAP_INT3   3
 
+/* From xen/include/asm-x86/x86-defns.h */
+#define X86_CR4_PGE        0x00000080 /* enable global pages */
+
+#ifndef ARRAY_SIZE
+#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
+#endif
+
 typedef struct vm_event {
     domid_t domain_id;
     xenevtchn_handle *xce_handle;
@@ -313,6 +320,24 @@ static void get_request(vm_event_t *vm_event, vm_event_request_t *req)
     back_ring->sring->req_event = req_cons + 1;
 }
 
+/*
+ * X86 control register names
+ */
+static const char* get_x86_ctrl_reg_name(uint32_t index)
+{
+    static const char* names[] = {
+        [VM_EVENT_X86_CR0]  = "CR0",
+        [VM_EVENT_X86_CR3]  = "CR3",
+        [VM_EVENT_X86_CR4]  = "CR4",
+        [VM_EVENT_X86_XCR0] = "XCR0",
+    };
+
+    if ( index >= ARRAY_SIZE(names) || names[index] == NULL )
+        return "";
+
+    return names[index];
+}
+
 /*
  * Note that this function is not thread safe.
  */
@@ -337,7 +362,7 @@ void usage(char* progname)
 {
     fprintf(stderr, "Usage: %s [-m] <domain_id> write|exec", progname);
 #if defined(__i386__) || defined(__x86_64__)
-            fprintf(stderr, "|breakpoint|altp2m_write|altp2m_exec|debug|cpuid|desc_access");
+            fprintf(stderr, "|breakpoint|altp2m_write|altp2m_exec|debug|cpuid|desc_access|write_ctrlreg_cr4");
 #elif defined(__arm__) || defined(__aarch64__)
             fprintf(stderr, "|privcall");
 #endif
@@ -369,6 +394,7 @@ int main(int argc, char *argv[])
     int debug = 0;
     int cpuid = 0;
     int desc_access = 0;
+    int write_ctrlreg_cr4 = 1;
     uint16_t altp2m_view_id = 0;
 
     char* progname = argv[0];
@@ -439,6 +465,10 @@ int main(int argc, char *argv[])
     {
         desc_access = 1;
     }
+    else if ( !strcmp(argv[0], "write_ctrlreg_cr4") )
+    {
+        write_ctrlreg_cr4 = 1;
+    }
 #elif defined(__arm__) || defined(__aarch64__)
     else if ( !strcmp(argv[0], "privcall") )
     {
@@ -596,6 +626,18 @@ int main(int argc, char *argv[])
         }
     }
 
+    if ( write_ctrlreg_cr4 )
+    {
+        /* Mask the CR4.PGE bit so no events will be generated for global TLB flushes. */
+        rc = xc_monitor_write_ctrlreg(xch, domain_id, VM_EVENT_X86_CR4, 1, 1,
+                                      X86_CR4_PGE, 1);
+        if ( rc < 0 )
+        {
+            ERROR("Error %d setting write control register trapping with vm_event\n", rc);
+            goto exit;
+        }
+    }
+
     /* Wait for access */
     for (;;)
     {
@@ -806,6 +848,15 @@ int main(int argc, char *argv[])
                        req.u.desc_access.is_write);
                 rsp.flags |= VM_EVENT_FLAG_EMULATE;
                 break;
+            case VM_EVENT_REASON_WRITE_CTRLREG:
+                printf("Control register written: rip=%016"PRIx64", vcpu %d: "
+                       "reg=%s, old_value=%016"PRIx64", new_value=%016"PRIx64"\n",
+                       req.data.regs.x86.rip,
+                       req.vcpu_id,
+                       get_x86_ctrl_reg_name(req.u.write_ctrlreg.index),
+                       req.u.write_ctrlreg.old_value,
+                       req.u.write_ctrlreg.new_value);
+                break;
             default:
                 fprintf(stderr, "UNKNOWN REASON CODE %d\n", req.reason);
             }