[PATCH v2] target/i386: Added consistency checks for CR4

[Lara Lazier]

All MBZ bits in CR4 must be zero. (APM2 15.5)
Added reserved bitmask and added checks in both
helper_vmrun and helper_write_crN.

Signed-off-by: Lara Lazier <laramglazier@gmail.com>
---
 target/i386/cpu.h                    | 31 ++++++++++++++++++++++++++++
 target/i386/tcg/sysemu/misc_helper.c |  3 +++
 target/i386/tcg/sysemu/svm_helper.c  |  9 +++++---
 3 files changed, 40 insertions(+), 3 deletions(-)

diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index 0b3057bdb6..a596e967f7 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -240,6 +240,7 @@ typedef enum X86Seg {
 #define CR4_OSFXSR_SHIFT 9
 #define CR4_OSFXSR_MASK (1U << CR4_OSFXSR_SHIFT)
 #define CR4_OSXMMEXCPT_MASK  (1U << 10)
+#define CR4_UMIP_MASK   (1U << 11)
 #define CR4_LA57_MASK   (1U << 12)
 #define CR4_VMXE_MASK   (1U << 13)
 #define CR4_SMXE_MASK   (1U << 14)
@@ -251,6 +252,36 @@ typedef enum X86Seg {
 #define CR4_PKE_MASK   (1U << 22)
 #define CR4_PKS_MASK   (1U << 24)
 
+#define CR4_RESERVED_MASK \
+(~(target_ulong)(CR4_VME_MASK | CR4_PVI_MASK | CR4_TSD_MASK \
+                | CR4_DE_MASK | CR4_PSE_MASK | CR4_PAE_MASK \
+                | CR4_MCE_MASK | CR4_PGE_MASK | CR4_PCE_MASK \
+                | CR4_OSFXSR_MASK | CR4_OSXMMEXCPT_MASK |CR4_UMIP_MASK \
+                | CR4_FSGSBASE_MASK | CR4_PCIDE_MASK | CR4_OSXSAVE_MASK \
+                | CR4_SMEP_MASK | CR4_SMAP_MASK | CR4_PKE_MASK | CR4_PKS_MASK))
+
+#define cr4_reserved_bits(env) \
+({ \
+    uint64_t __reserved_bits = CR4_RESERVED_MASK; \
+    if (!env->features[FEAT_XSAVE]) \
+        __reserved_bits |= CR4_OSXSAVE_MASK; \
+    if (!(env->features[FEAT_7_0_EBX] & CPUID_7_0_EBX_SMEP)) \
+        __reserved_bits |= CR4_SMEP_MASK; \
+    if (!(env->features[FEAT_7_0_EBX] & CPUID_7_0_EBX_SMAP)) \
+        __reserved_bits |= CR4_SMAP_MASK; \
+    if (!(env->features[FEAT_7_0_EBX] & CPUID_7_0_EBX_FSGSBASE)) \
+        __reserved_bits |= CR4_FSGSBASE_MASK; \
+    if (!(env->features[FEAT_7_0_ECX] & CPUID_7_0_ECX_PKU)) \
+        __reserved_bits |= CR4_PKE_MASK; \
+    if (!(env->features[FEAT_7_0_ECX] & CPUID_7_0_ECX_LA57)) \
+        __reserved_bits |= CR4_LA57_MASK; \
+    if (!(env->features[FEAT_7_0_ECX] & CPUID_7_0_ECX_UMIP)) \
+        __reserved_bits |= CR4_UMIP_MASK; \
+    if (!(env->features[FEAT_7_0_ECX] & CPUID_7_0_ECX_PKS)) \
+        __reserved_bits |= CR4_PKS_MASK; \
+    __reserved_bits; \
+})
+
 #define DR6_BD          (1 << 13)
 #define DR6_BS          (1 << 14)
 #define DR6_BT          (1 << 15)
diff --git a/target/i386/tcg/sysemu/misc_helper.c 
b/target/i386/tcg/sysemu/misc_helper.c
index db0d8a9d79..a2af2c9bba 100644
--- a/target/i386/tcg/sysemu/misc_helper.c
+++ b/target/i386/tcg/sysemu/misc_helper.c
@@ -99,6 +99,9 @@ void helper_write_crN(CPUX86State *env, int reg, target_ulong 
t0)
         cpu_x86_update_cr3(env, t0);
         break;
     case 4:
+        if (t0 & cr4_reserved_bits(env)) {
+            cpu_vmexit(env, SVM_EXIT_ERR, 0, GETPC());
+        }
         if (((t0 ^ env->cr[4]) & CR4_LA57_MASK) &&
             (env->hflags & HF_CS64_MASK)) {
             raise_exception_ra(env, EXCP0D_GPF, GETPC());
diff --git a/target/i386/tcg/sysemu/svm_helper.c 
b/target/i386/tcg/sysemu/svm_helper.c
index b6df36d4e5..37dbe8e434 100644
--- a/target/i386/tcg/sysemu/svm_helper.c
+++ b/target/i386/tcg/sysemu/svm_helper.c
@@ -111,6 +111,7 @@ void helper_vmrun(CPUX86State *env, int aflag, int 
next_eip_addend)
     uint32_t int_ctl;
     uint32_t asid;
     uint64_t new_cr0;
+    uint64_t new_cr4;
 
     cpu_svm_check_intercept_param(env, SVM_EXIT_VMRUN, 0, GETPC());
 
@@ -251,14 +252,16 @@ void helper_vmrun(CPUX86State *env, int aflag, int 
next_eip_addend)
     if ((new_cr0 & CR0_NW_MASK) && !(new_cr0 & CR0_CD_MASK)) {
         cpu_vmexit(env, SVM_EXIT_ERR, 0, GETPC());
     }
+    new_cr4 = x86_ldq_phys(cs, env->vm_vmcb + offsetof(struct vmcb, save.cr4));
+    if (new_cr4 & cr4_reserved_bits(env)) {
+        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, new_cr0);
-    cpu_x86_update_cr4(env, x86_ldq_phys(cs,
-                                     env->vm_vmcb + offsetof(struct vmcb,
-                                                             save.cr4)));
+    cpu_x86_update_cr4(env, new_cr4);
     cpu_x86_update_cr3(env, x86_ldq_phys(cs,
                                      env->vm_vmcb + offsetof(struct vmcb,
                                                              save.cr3)));
-- 
2.25.1