[PATCH 2/3] target/i386: Added consistency checks for CR0

[Lara Lazier]

The combination of unset CD and set NW bit in CR0 is illegal.
CR0[63:32] are also reserved and need to be zero.
(AMD64 Architecture Programmer's Manual, V2, 15.5)

Signed-off-by: Lara Lazier <laramglazier@gmail.com>
---
 target/i386/cpu.h                   |  2 ++
 target/i386/svm.h                   |  1 +
 target/i386/tcg/sysemu/svm_helper.c | 12 +++++++++---
 3 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index ac3abea97c..46542513cc 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -224,6 +224,8 @@ typedef enum X86Seg {
 #define CR0_NE_MASK  (1U << 5)
 #define CR0_WP_MASK  (1U << 16)
 #define CR0_AM_MASK  (1U << 18)
+#define CR0_NW_MASK  (1U << 29)
+#define CR0_CD_MASK  (1U << 30)
 #define CR0_PG_MASK  (1U << 31)
 
 #define CR4_VME_MASK  (1U << 0)
diff --git a/target/i386/svm.h b/target/i386/svm.h
index 1c55d4f829..7a88906907 100644
--- a/target/i386/svm.h
+++ b/target/i386/svm.h
@@ -136,6 +136,7 @@
 #define SVM_NPTEXIT_GPT     (1ULL << 33)
 
 #define SVM_VMRUN_INTERCEPT (1ULL << 32)
+#define SVM_CR0_RESERVED_MASK 0xffffffff00000000U
 
 struct QEMU_PACKED vmcb_control_area {
        uint16_t intercept_cr_read;
diff --git a/target/i386/tcg/sysemu/svm_helper.c 
b/target/i386/tcg/sysemu/svm_helper.c
index ff826fe11a..63aaa53490 100644
--- a/target/i386/tcg/sysemu/svm_helper.c
+++ b/target/i386/tcg/sysemu/svm_helper.c
@@ -73,6 +73,7 @@ void helper_vmrun(CPUX86State *env, int aflag, int 
next_eip_addend)
     uint32_t event_inj;
     uint32_t int_ctl;
     uint32_t asid;
+    uint64_t new_cr0;
 
     cpu_svm_check_intercept_param(env, SVM_EXIT_VMRUN, 0, GETPC());
 
@@ -192,13 +193,18 @@ void helper_vmrun(CPUX86State *env, int aflag, int 
next_eip_addend)
     env->idt.limit = x86_ldl_phys(cs, env->vm_vmcb + offsetof(struct vmcb,
                                                       save.idtr.limit));
 
+    new_cr0 = x86_ldq_phys(cs, env->vm_vmcb + offsetof(struct vmcb, save.cr0));
+    if (new_cr0 & SVM_CR0_RESERVED_MASK) {
+        cpu_vmexit(env, SVM_EXIT_ERR, 0, GETPC());
+    }
+    if ((new_cr0 & CR0_NW_MASK) && !(new_cr0 & CR0_CD_MASK)) {
+        cpu_vmexit(env, SVM_EXIT_ERR, 0, GETPC());
+    }
     /* clear exit_info_2 so we behave like the real hardware */
     x86_stq_phys(cs,
              env->vm_vmcb + offsetof(struct vmcb, control.exit_info_2), 0);
 
-    cpu_x86_update_cr0(env, x86_ldq_phys(cs,
-                                     env->vm_vmcb + offsetof(struct vmcb,
-                                                             save.cr0)));
+    cpu_x86_update_cr0(env, new_cr0);
     cpu_x86_update_cr4(env, x86_ldq_phys(cs,
                                      env->vm_vmcb + offsetof(struct vmcb,
                                                              save.cr4)));
-- 
2.25.1