KVM: x86 emulator: fix eflags preparation for emulation

We prepare eflags for the emulated instruction, then clobber it with an 'andl'.
Fix by popping eflags as the last thing in the sequence.

Patch taken from Xen (16143:959b4b92b6bf)

Signed-off-by: Avi Kivity <avi@qumranet.com>

drivers/kvm/x86_emulate.c

@@ -256,21 +256,21 @@ static u16 twobyte_table[256] = {
 #define EFLAGS_MASK (EFLG_OF|EFLG_SF|EFLG_ZF|EFLG_AF|EFLG_PF|EFLG_CF)
 
 /* Before executing instruction: restore necessary bits in EFLAGS. */
-#define _PRE_EFLAGS(_sav, _msk, _tmp) \
+#define _PRE_EFLAGS(_sav, _msk, _tmp)					\
-	/* EFLAGS = (_sav & _msk) | (EFLAGS & ~_msk); */	\
+	/* EFLAGS = (_sav & _msk) | (EFLAGS & ~_msk); _sav &= ~_msk; */ \
-	"push %"_sav"; "					\
+	"movl %"_sav",%"_LO32 _tmp"; "                                  \
-	"movl %"_msk",%"_LO32 _tmp"; "				\
+	"push %"_tmp"; "                                                \
-	"andl %"_LO32 _tmp",("_STK"); "				\
+	"push %"_tmp"; "                                                \
-	"pushf; "						\
+	"movl %"_msk",%"_LO32 _tmp"; "                                  \
-	"notl %"_LO32 _tmp"; "					\
+	"andl %"_LO32 _tmp",("_STK"); "                                 \
-	"andl %"_LO32 _tmp",("_STK"); "				\
+	"pushf; "                                                       \
-	"pop  %"_tmp"; "					\
+	"notl %"_LO32 _tmp"; "                                          \
-	"orl  %"_LO32 _tmp",("_STK"); "				\
+	"andl %"_LO32 _tmp",("_STK"); "                                 \
-	"popf; "						\
+	"andl %"_LO32 _tmp","__stringify(BITS_PER_LONG/4)"("_STK"); "	\
-	/* _sav &= ~msk; */					\
+	"pop  %"_tmp"; "                                                \
-	"movl %"_msk",%"_LO32 _tmp"; "				\
+	"orl  %"_LO32 _tmp",("_STK"); "                                 \
-	"notl %"_LO32 _tmp"; "					\
+	"popf; "                                                        \
-	"andl %"_LO32 _tmp",%"_sav"; "
+	"pop  %"_sav"; "
 
 /* After executing instruction: write-back necessary bits in EFLAGS. */
 #define _POST_EFLAGS(_sav, _msk, _tmp) \