tools/hvmloader: Fix non-deterministic cpuid()

hvmloader's cpuid() implementation deviates from Xen's in that the value
passed on ecx is unspecified. This means that when used on leaves that
implement subleaves it's unspecified which one you get; though it's more
than likely an invalid one.

Import Xen's implementation so there are no surprises.

Fixes: 318ac791f9f9 ("Add utilities needed for SMBIOS generation to hvmloader")
Signed-off-by: Alejandro Vallejo <alejandro.vallejo@cloud.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>

diff --git a/tools/firmware/hvmloader/util.c b/tools/firmware/hvmloader/util.c
index c34f077b38e38b5319626d1bfb4e4f52de560afb..d3b3f9038e64c1b27005f1097656f99558ec8d1d 100644 (file)
--- 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 deb823a892ef223c5577ae057bb16fdccfd3c3f1..17ed3783f21328c62dfb887f2166ae75566dd9f2 100644 (file)
--- 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)