diff --git a/tools/firmware/hvmloader/util.c b/tools/firmware/hvmloader/util.c
index c34f077b38..d3b3f9038e 100644
--- a/tools/firmware/hvmloader/util.c
+++ b/tools/firmware/hvmloader/util.c
@@ -267,15 +267,6 @@ memcmp(const void *s1, const void *s2, unsigned n)
     return 0;
 }
 
-void
-cpuid(uint32_t idx, uint32_t *eax, uint32_t *ebx, uint32_t *ecx, uint32_t *edx)
-{
-    asm volatile (
-        "cpuid"
-        : "=a" (*eax), "=b" (*ebx), "=c" (*ecx), "=d" (*edx)
-        : "0" (idx) );
-}
-
 static const char hex_digits[] = "0123456789abcdef";
 
 /* Write a two-character hex representation of 'byte' to digits[].
diff --git a/tools/firmware/hvmloader/util.h b/tools/firmware/hvmloader/util.h
index deb823a892..17ed3783f2 100644
--- a/tools/firmware/hvmloader/util.h
+++ b/tools/firmware/hvmloader/util.h
@@ -184,9 +184,30 @@ int uart_exists(uint16_t uart_base);
 int lpt_exists(uint16_t lpt_base);
 int hpet_exists(unsigned long hpet_base);
 
-/* Do cpuid instruction, with operation 'idx' */
-void cpuid(uint32_t idx, uint32_t *eax, uint32_t *ebx,
-           uint32_t *ecx, uint32_t *edx);
+/* Some CPUID calls want 'count' to be placed in ecx */
+static inline void cpuid_count(
+    uint32_t leaf,
+    uint32_t subleaf,
+    uint32_t *eax,
+    uint32_t *ebx,
+    uint32_t *ecx,
+    uint32_t *edx)
+{
+    asm volatile ( "cpuid"
+                   : "=a" (*eax), "=b" (*ebx), "=c" (*ecx), "=d" (*edx)
+                   : "a" (leaf), "c" (subleaf) );
+}
+
+/* Generic CPUID function (subleaf 0) */
+static inline void cpuid(
+    uint32_t leaf,
+    uint32_t *eax,
+    uint32_t *ebx,
+    uint32_t *ecx,
+    uint32_t *edx)
+{
+    cpuid_count(leaf, 0, eax, ebx, ecx, edx);
+}
 
 /* Read the TSC register. */
 static inline uint64_t rdtsc(void)