[PATCH v4 12/23] i386/cpu: Enable xsave support for CET states

[Zhao Liu <zhao1.liu@intel.com>]

From: Yang Weijiang <weijiang.yang@intel.com>

Add CET_U/S bits in xstate area and report support in xstate
feature mask.
MSR_XSS[bit 11] corresponds to CET user mode states.
MSR_XSS[bit 12] corresponds to CET supervisor mode states.

CET Shadow Stack(SHSTK) and Indirect Branch Tracking(IBT) features
are enumerated via CPUID.(EAX=07H,ECX=0H):ECX[7] and EDX[20]
respectively, two features share the same state bits in XSS, so
if either of the features is enabled, set CET_U and CET_S bits
together.

Tested-by: Farrah Chen <farrah.chen@intel.com>
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
Co-developed-by: Chao Gao <chao.gao@intel.com>
Signed-off-by: Chao Gao <chao.gao@intel.com>
Co-developed-by: Zhao Liu <zhao1.liu@intel.com>
Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
---
Changes Since v2:
 - Rename XSavesCETU/XSavesCETS to XSaveCETU/XSaveCETS.
 - Refine the comments.
 - Drop ".offset = 0" and its comment.
 - Re-describe xstate dependencies via features array.
 - Drop "cet-u" & "cet-s" enumeration from FEAT_XSAVE_XSS_LO's
   feat_name array sicne currently xsave doesn't use named features.
---
 target/i386/cpu.c | 14 ++++++++++++++
 target/i386/cpu.h | 26 +++++++++++++++++++++++++-
 2 files changed, 39 insertions(+), 1 deletion(-)

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index d2a89c03caec..4d29e784061c 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -2078,6 +2078,20 @@ ExtSaveArea x86_ext_save_areas[XSAVE_STATE_AREA_COUNT] = {
             { FEAT_7_0_ECX,         CPUID_7_0_ECX_PKU },
         },
     },
+    [XSTATE_CET_U_BIT] = {
+        .size = sizeof(XSaveCETU),
+        .features = {
+            { FEAT_7_0_ECX,         CPUID_7_0_ECX_CET_SHSTK },
+            { FEAT_7_0_EDX,         CPUID_7_0_EDX_CET_IBT },
+        },
+    },
+    [XSTATE_CET_S_BIT] = {
+        .size = sizeof(XSaveCETS),
+        .features = {
+            { FEAT_7_0_ECX,         CPUID_7_0_ECX_CET_SHSTK },
+            { FEAT_7_0_EDX,         CPUID_7_0_EDX_CET_IBT },
+        },
+    },
     [XSTATE_ARCH_LBR_BIT] = {
         .size = sizeof(XSaveArchLBR),
         .features = {
diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index f065527757c4..bfc38830e29e 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -589,6 +589,8 @@ typedef enum X86Seg {
 #define XSTATE_Hi16_ZMM_BIT             7
 #define XSTATE_PT_BIT                   8
 #define XSTATE_PKRU_BIT                 9
+#define XSTATE_CET_U_BIT                11
+#define XSTATE_CET_S_BIT                12
 #define XSTATE_ARCH_LBR_BIT             15
 #define XSTATE_XTILE_CFG_BIT            17
 #define XSTATE_XTILE_DATA_BIT           18
@@ -603,6 +605,8 @@ typedef enum X86Seg {
 #define XSTATE_Hi16_ZMM_MASK            (1ULL << XSTATE_Hi16_ZMM_BIT)
 #define XSTATE_PT_MASK                  (1ULL << XSTATE_PT_BIT)
 #define XSTATE_PKRU_MASK                (1ULL << XSTATE_PKRU_BIT)
+#define XSTATE_CET_U_MASK               (1ULL << XSTATE_CET_U_BIT)
+#define XSTATE_CET_S_MASK               (1ULL << XSTATE_CET_S_BIT)
 #define XSTATE_ARCH_LBR_MASK            (1ULL << XSTATE_ARCH_LBR_BIT)
 #define XSTATE_XTILE_CFG_MASK           (1ULL << XSTATE_XTILE_CFG_BIT)
 #define XSTATE_XTILE_DATA_MASK          (1ULL << XSTATE_XTILE_DATA_BIT)
@@ -628,7 +632,8 @@ typedef enum X86Seg {
                                  XSTATE_XTILE_CFG_MASK | XSTATE_XTILE_DATA_MASK)
 
 /* CPUID feature bits available in XSS */
-#define CPUID_XSTATE_XSS_MASK    (XSTATE_ARCH_LBR_MASK)
+#define CPUID_XSTATE_XSS_MASK   (XSTATE_ARCH_LBR_MASK | XSTATE_CET_U_MASK | \
+                                 XSTATE_CET_S_MASK)
 
 #define CPUID_XSTATE_MASK       (CPUID_XSTATE_XCR0_MASK | CPUID_XSTATE_XSS_MASK)
 
@@ -907,6 +912,8 @@ uint64_t x86_cpu_get_supported_feature_word(X86CPU *cpu, FeatureWord w);
 #define CPUID_7_0_ECX_WAITPKG           (1U << 5)
 /* Additional AVX-512 Vector Byte Manipulation Instruction */
 #define CPUID_7_0_ECX_AVX512_VBMI2      (1U << 6)
+/* Control-flow enforcement technology: shadow stack */
+#define CPUID_7_0_ECX_CET_SHSTK         (1U << 7)
 /* Galois Field New Instructions */
 #define CPUID_7_0_ECX_GFNI              (1U << 8)
 /* Vector AES Instructions */
@@ -954,6 +961,8 @@ uint64_t x86_cpu_get_supported_feature_word(X86CPU *cpu, FeatureWord w);
 #define CPUID_7_0_EDX_TSX_LDTRK         (1U << 16)
 /* Architectural LBRs */
 #define CPUID_7_0_EDX_ARCH_LBR          (1U << 19)
+/* Control-flow enforcement technology: indirect branch tracking */
+#define CPUID_7_0_EDX_CET_IBT           (1U << 20)
 /* AMX_BF16 instruction */
 #define CPUID_7_0_EDX_AMX_BF16          (1U << 22)
 /* AVX512_FP16 instruction */
@@ -1740,6 +1749,19 @@ typedef struct XSavePKRU {
     uint32_t padding;
 } XSavePKRU;
 
+/* Ext. save area 11: CET_U state */
+typedef struct XSaveCETU {
+    uint64_t u_cet;
+    uint64_t pl3_ssp;
+} XSaveCETU;
+
+/* Ext. save area 12: CET_S state */
+typedef struct XSaveCETS {
+    uint64_t pl0_ssp;
+    uint64_t pl1_ssp;
+    uint64_t pl2_ssp;
+} XSaveCETS;
+
 /* Ext. save area 15: Arch LBR state */
 typedef struct XSaveArchLBR {
     uint64_t lbr_ctl;
@@ -1767,6 +1789,8 @@ QEMU_BUILD_BUG_ON(sizeof(XSaveOpmask) != 0x40);
 QEMU_BUILD_BUG_ON(sizeof(XSaveZMM_Hi256) != 0x200);
 QEMU_BUILD_BUG_ON(sizeof(XSaveHi16_ZMM) != 0x400);
 QEMU_BUILD_BUG_ON(sizeof(XSavePKRU) != 0x8);
+QEMU_BUILD_BUG_ON(sizeof(XSaveCETU) != 0x10);
+QEMU_BUILD_BUG_ON(sizeof(XSaveCETS) != 0x18);
 QEMU_BUILD_BUG_ON(sizeof(XSaveArchLBR) != 0x328);
 QEMU_BUILD_BUG_ON(sizeof(XSaveXTILECFG) != 0x40);
 QEMU_BUILD_BUG_ON(sizeof(XSaveXTILEDATA) != 0x2000);
-- 
2.34.1