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c::is_xen() use cpuid in order to detect we're under XEN
diff -up ./c/stuff.xs.pl.tv2 ./c/stuff.xs.pl
--- ./c/stuff.xs.pl.tv2 2012-01-09 10:49:22.807894338 +0100
+++ ./c/stuff.xs.pl 2012-01-09 11:03:04.124482279 +0100
@@ -105,6 +105,40 @@ int length_of_space_padded(char *str, in
return len;
}
+int pv_context;
+static void cpuid(uint32_t idx,
+ uint32_t *eax,
+ uint32_t *ebx,
+ uint32_t *ecx,
+ uint32_t *edx)
+{
+ asm volatile (
+ "test %1,%1 ; jz 1f ; ud2a ; .ascii \"xen\" ; 1: cpuid"
+ : "=a" (*eax), "=b" (*ebx), "=c" (*ecx), "=d" (*edx)
+ : "0" (idx), "1" (pv_context) );
+}
+
+static int check_for_xen(void)
+{
+ uint32_t eax, ebx, ecx, edx;
+ char signature[13];
+
+ cpuid(0x40000000, &eax, &ebx, &ecx, &edx);
+ *(uint32_t *)(signature + 0) = ebx;
+ *(uint32_t *)(signature + 4) = ecx;
+ *(uint32_t *)(signature + 8) = edx;
+ signature[12] = ' . "'\0'" . ';
+
+ if ( strcmp("XenVMMXenVMM", signature) || (eax < 0x40000002) )
+ return 0;
+
+ cpuid(0x40000001, &eax, &ebx, &ecx, &edx);
+ printf("Running in %s context on Xen v%d.%d.\n",
+ pv_context ? "PV" : "HVM", (uint16_t)(eax >> 16), (uint16_t)eax);
+ return 1;
+}
+
+
MODULE = c::stuff PACKAGE = c::stuff
';
@@ -116,6 +150,46 @@ pcmcia_probe()
print '
int
+is_xen()
+ CODE:
+ pid_t pid;
+ int status;
+ uint32_t dummy;
+
+ /* Check for execution in HVM context. */
+ if ( check_for_xen() )
+ return 0;
+
+ /* Now we check for execution in PV context. */
+ pv_context = 1;
+
+ /*
+ * Fork a child to test the paravirtualised CPUID instruction.
+ * If executed outside Xen PV context, the extended opcode will fault.
+ */
+ pid = fork();
+ switch ( pid )
+ {
+ case 0:
+ /* Child: test paravirtualised CPUID opcode and then exit cleanly. */
+ cpuid(0x40000000, &dummy, &dummy, &dummy, &dummy);
+ exit(0);
+ case -1:
+ fprintf(stderr, "Fork failed.\n");
+ return 0;
+ }
+
+ /*
+ * Parent waits for child to terminate and checks for clean exit.
+ * Only if the exit is clean is it safe for us to try the extended CPUID.
+ */
+ waitpid(pid, &status, 0);
+ if ( WIFEXITED(status) && check_for_xen() )
+ return 0;
+
+ return 0;
+
+int
del_partition(hd, part_number)
int hd
int part_number
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