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[PULL,30/53] target/i386: implement undocumented "smsw r32" behavior

Message ID 20200706164155.24696-31-pbonzini@redhat.com
State New
Headers show
Series [PULL,01/53] tcg/svm: use host cr4 during NPT page table walk | expand

Commit Message

Paolo Bonzini July 6, 2020, 4:41 p.m. UTC 
In 32-bit mode, the higher 16 bits of the destination
register are undefined.  In practice CR0[31:0] is stored,
just like in 64-bit mode, so just remove the "if" that
currently differentiates the behavior.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reported-by: Roman Bolshakov <r.bolshakov@yadro.com>
Reviewed-by: Roman Bolshakov <r.bolshakov@yadro.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 target/i386/translate.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)
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Patch

diff --git a/target/i386/translate.c b/target/i386/translate.c
index 5ef72ff401..a1d31f09c1 100644
--- a/target/i386/translate.c
+++ b/target/i386/translate.c
@@ -7579,12 +7579,13 @@  static target_ulong disas_insn(DisasContext *s, CPUState *cpu)
         CASE_MODRM_OP(4): /* smsw */
             gen_svm_check_intercept(s, pc_start, SVM_EXIT_READ_CR0);
             tcg_gen_ld_tl(s->T0, cpu_env, offsetof(CPUX86State, cr[0]));
-            if (CODE64(s)) {
-                mod = (modrm >> 6) & 3;
-                ot = (mod != 3 ? MO_16 : s->dflag);
-            } else {
-                ot = MO_16;
-            }
+            /*
+             * In 32-bit mode, the higher 16 bits of the destination
+             * register are undefined.  In practice CR0[31:0] is stored
+             * just like in 64-bit mode.
+             */
+            mod = (modrm >> 6) & 3;
+            ot = (mod != 3 ? MO_16 : s->dflag);
             gen_ldst_modrm(env, s, modrm, ot, OR_TMP0, 1);
             break;
         case 0xee: /* rdpkru */