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>

diff --git a/drivers/kvm/x86_emulate.c b/drivers/kvm/x86_emulate.c
index 2e259a847697a1b116fdfdfbc9958bad585d7df3..f423b0e327f44c820ade44c66566bfe3921cdcb3 100644 (file)
--- a/drivers/kvm/x86_emulate.c
+++ b/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) \
-       /* EFLAGS = (_sav & _msk) | (EFLAGS & ~_msk); */        \
-       "push %"_sav"; "                                        \
-       "movl %"_msk",%"_LO32 _tmp"; "                          \
-       "andl %"_LO32 _tmp",("_STK"); "                         \
-       "pushf; "                                               \
-       "notl %"_LO32 _tmp"; "                                  \
-       "andl %"_LO32 _tmp",("_STK"); "                         \
-       "pop  %"_tmp"; "                                        \
-       "orl  %"_LO32 _tmp",("_STK"); "                         \
-       "popf; "                                                \
-       /* _sav &= ~msk; */                                     \
-       "movl %"_msk",%"_LO32 _tmp"; "                          \
-       "notl %"_LO32 _tmp"; "                                  \
-       "andl %"_LO32 _tmp",%"_sav"; "
+#define _PRE_EFLAGS(_sav, _msk, _tmp)                                  \
+       /* EFLAGS = (_sav & _msk) | (EFLAGS & ~_msk); _sav &= ~_msk; */ \
+       "movl %"_sav",%"_LO32 _tmp"; "                                  \
+       "push %"_tmp"; "                                                \
+       "push %"_tmp"; "                                                \
+       "movl %"_msk",%"_LO32 _tmp"; "                                  \
+       "andl %"_LO32 _tmp",("_STK"); "                                 \
+       "pushf; "                                                       \
+       "notl %"_LO32 _tmp"; "                                          \
+       "andl %"_LO32 _tmp",("_STK"); "                                 \
+       "andl %"_LO32 _tmp","__stringify(BITS_PER_LONG/4)"("_STK"); "   \
+       "pop  %"_tmp"; "                                                \
+       "orl  %"_LO32 _tmp",("_STK"); "                                 \
+       "popf; "                                                        \
+       "pop  %"_sav"; "
 
 /* After executing instruction: write-back necessary bits in EFLAGS. */
 #define _POST_EFLAGS(_sav, _msk, _tmp) \