x86: Implement SMEP and SMAP

This patch implements Supervisor Mode Execution Prevention (SMEP) and
Supervisor Mode Access Prevention (SMAP) for x86.  The purpose of the
patch, obviously, is to help kernel developers debug the support for
those features.

A fair bit of the code relates to the handling of CPUID features.  The
CPUID code probably would get greatly simplified if all the feature
bit words were unified into a single vector object, but in the
interest of producing a minimal patch for SMEP/SMAP, and because I had
very limited time for this project, I followed the existing style.

[ v2: don't change the definition of the qemu64 CPU shorthand, since
  that breaks loading old snapshots.  Per Anthony Liguori this can be
  fixed once the CPU feature set is snapshot.

  Change the coding style slightly to conform to checkpatch.pl. ]

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

1 files changed, 26 insertions, 7 deletions

diff --git a/target-i386/cpu.h b/target-i386/cpu.h
index 49950843f..e4a7d5b6e 100644
--- a/target-i386/cpu.h
+++ b/target-i386/cpu.h
@@ -123,8 +123,8 @@
 
 /* hidden flags - used internally by qemu to represent additional cpu
    states. Only the CPL, INHIBIT_IRQ, SMM and SVMI are not
-   redundant. We avoid using the IOPL_MASK, TF_MASK and VM_MASK bit
-   position to ease oring with eflags. */
+   redundant. We avoid using the IOPL_MASK, TF_MASK, VM_MASK and AC_MASK
+   bit positions to ease oring with eflags. */
 /* current cpl */
 #define HF_CPL_SHIFT         0
 /* true if soft mmu is being used */
@@ -147,10 +147,12 @@
 #define HF_CS64_SHIFT       15 /* only used on x86_64: 64 bit code segment  */
 #define HF_RF_SHIFT         16 /* must be same as eflags */
 #define HF_VM_SHIFT         17 /* must be same as eflags */
+#define HF_AC_SHIFT         18 /* must be same as eflags */
 #define HF_SMM_SHIFT        19 /* CPU in SMM mode */
 #define HF_SVME_SHIFT       20 /* SVME enabled (copy of EFER.SVME) */
 #define HF_SVMI_SHIFT       21 /* SVM intercepts are active */
 #define HF_OSFXSR_SHIFT     22 /* CR4.OSFXSR */
+#define HF_SMAP_SHIFT       23 /* CR4.SMAP */
 
 #define HF_CPL_MASK          (3 << HF_CPL_SHIFT)
 #define HF_SOFTMMU_MASK      (1 << HF_SOFTMMU_SHIFT)
@@ -168,10 +170,12 @@
 #define HF_CS64_MASK         (1 << HF_CS64_SHIFT)
 #define HF_RF_MASK           (1 << HF_RF_SHIFT)
 #define HF_VM_MASK           (1 << HF_VM_SHIFT)
+#define HF_AC_MASK           (1 << HF_AC_SHIFT)
 #define HF_SMM_MASK          (1 << HF_SMM_SHIFT)
 #define HF_SVME_MASK         (1 << HF_SVME_SHIFT)
 #define HF_SVMI_MASK         (1 << HF_SVMI_SHIFT)
 #define HF_OSFXSR_MASK       (1 << HF_OSFXSR_SHIFT)
+#define HF_SMAP_MASK         (1 << HF_SMAP_SHIFT)
 
 /* hflags2 */
 
@@ -210,6 +214,13 @@
 #define CR4_OSFXSR_SHIFT 9
 #define CR4_OSFXSR_MASK (1 << CR4_OSFXSR_SHIFT)
 #define CR4_OSXMMEXCPT_MASK  (1 << 10)
+#define CR4_VMXE_MASK   (1 << 13)
+#define CR4_SMXE_MASK   (1 << 14)
+#define CR4_FSGSBASE_MASK (1 << 16)
+#define CR4_PCIDE_MASK  (1 << 17)
+#define CR4_OSXSAVE_MASK (1 << 18)
+#define CR4_SMEP_MASK   (1 << 20)
+#define CR4_SMAP_MASK   (1 << 21)
 
 #define DR6_BD          (1 << 13)
 #define DR6_BS          (1 << 14)
@@ -474,6 +485,9 @@
 #define CPUID_SVM_PAUSEFILTER  (1 << 10)
 #define CPUID_SVM_PFTHRESHOLD  (1 << 12)
 
+#define CPUID_7_0_EBX_SMEP     (1 << 7)
+#define CPUID_7_0_EBX_SMAP     (1 << 20)
+
 #define CPUID_VENDOR_INTEL_1 0x756e6547 /* "Genu" */
 #define CPUID_VENDOR_INTEL_2 0x49656e69 /* "ineI" */
 #define CPUID_VENDOR_INTEL_3 0x6c65746e /* "ntel" */
@@ -649,7 +663,7 @@ typedef struct {
 #define CPU_NB_REGS CPU_NB_REGS32
 #endif
 
-#define NB_MMU_MODES 2
+#define NB_MMU_MODES 3
 
 typedef enum TPRAccess {
     TPR_ACCESS_READ,
@@ -779,7 +793,7 @@ typedef struct CPUX86State {
     uint32_t cpuid_xlevel2;
     uint32_t cpuid_ext4_features;
     /* Flags from CPUID[EAX=7,ECX=0].EBX */
-    uint32_t cpuid_7_0_ebx;
+    uint32_t cpuid_7_0_ebx_features;
 
     /* MTRRs */
     uint64_t mtrr_fixed[11];
@@ -1018,10 +1032,15 @@ static inline CPUX86State *cpu_init(const char *cpu_model)
 /* MMU modes definitions */
 #define MMU_MODE0_SUFFIX _kernel
 #define MMU_MODE1_SUFFIX _user
-#define MMU_USER_IDX 1
+#define MMU_MODE2_SUFFIX _ksmap /* Kernel with SMAP override */
+#define MMU_KERNEL_IDX  0
+#define MMU_USER_IDX    1
+#define MMU_KSMAP_IDX   2
 static inline int cpu_mmu_index (CPUX86State *env)
 {
-    return (env->hflags & HF_CPL_MASK) == 3 ? 1 : 0;
+    return (env->hflags & HF_CPL_MASK) == 3 ? MMU_USER_IDX :
+        ((env->hflags & HF_SMAP_MASK) && (env->eflags & AC_MASK))
+        ? MMU_KSMAP_IDX : MMU_KERNEL_IDX;
 }
 
 #undef EAX
@@ -1107,7 +1126,7 @@ static inline void cpu_get_tb_cpu_state(CPUX86State *env, target_ulong *pc,
     *cs_base = env->segs[R_CS].base;
     *pc = *cs_base + env->eip;
     *flags = env->hflags |
-        (env->eflags & (IOPL_MASK | TF_MASK | RF_MASK | VM_MASK));
+        (env->eflags & (IOPL_MASK | TF_MASK | RF_MASK | VM_MASK | AC_MASK));
 }
 
 void do_cpu_init(X86CPU *cpu);