On Wed, May 06, 2015 at 12:38:29PM +0200, Paolo Bonzini wrote:
Bits 16-31 of the SMM revision ID are feature bits.
We only need to
check that SMBASE relocation is supported, but do not care about other
features. In particular, this allows the SMM I/O instruction restart
feature to be present.
Signed-off-by: Paolo Bonzini <pbonzini(a)redhat.com>
---
src/fw/smm.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)
diff --git a/src/fw/smm.c b/src/fw/smm.c
index dabc677..6cb484e 100644
--- a/src/fw/smm.c
+++ b/src/fw/smm.c
@@ -18,8 +18,14 @@
#include "util.h" // smm_setup
#include "x86.h" // wbinvd
-#define SMM_REV_I32 0x00020000
-#define SMM_REV_I64 0x00020064
+/*
+ * Check SMM state save area format (bits 0-15) and require support
+ * for SMBASE relocation.
+ */
+#define SMM_REV_MASK 0x0002ffff
+
+#define SMM_REV_I32 0x00020000
+#define SMM_REV_I64 0x00020064
struct smm_state {
union {
@@ -62,9 +68,10 @@ handle_smi(u16 cs)
if (smm == (void*)BUILD_SMM_INIT_ADDR) {
// relocate SMBASE to 0xa0000
- if (smm->cpu.i32.smm_rev == SMM_REV_I32) {
+ u32 rev = smm->cpu.i32.smm_rev & SMM_REV_MASK;
+ if (rev == SMM_REV_I32) {
I noticed that this patch from May changes the revision check to use a
mask in the SMM init code, but doesn't change the check in the runtime
part of the handler. Was this intentional?
-Kevin