target/i386: Enable support for XSAVES based features

There're some new features, including Arch LBR, depending
on XSAVES/XRSTORS support, the new instructions will
save/restore data based on feature bits enabled in XCR0 | XSS.
This patch adds the basic support for related CPUID enumeration
and meanwhile changes the name from FEAT_XSAVE_COMP_{LO|HI} to
FEAT_XSAVE_XCR0_{LO|HI} to differentiate clearly the feature
bits in XCR0 and those in XSS.

Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
Message-Id: <20220215195258.29149-5-weijiang.yang@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

2 files changed, 92 insertions, 26 deletions

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index 856a865..643536d 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -937,6 +937,34 @@ FeatureWordInfo feature_word_info[FEATURE_WORDS] = {
         },
         .tcg_features = TCG_XSAVE_FEATURES,
     },
+    [FEAT_XSAVE_XSS_LO] = {
+        .type = CPUID_FEATURE_WORD,
+        .feat_names = {
+            NULL, NULL, NULL, NULL,
+            NULL, NULL, NULL, NULL,
+            NULL, NULL, NULL, NULL,
+            NULL, NULL, NULL, NULL,
+            NULL, NULL, NULL, NULL,
+            NULL, NULL, NULL, NULL,
+            NULL, NULL, NULL, NULL,
+            NULL, NULL, NULL, NULL,
+        },
+        .cpuid = {
+            .eax = 0xD,
+            .needs_ecx = true,
+            .ecx = 1,
+            .reg = R_ECX,
+        },
+    },
+    [FEAT_XSAVE_XSS_HI] = {
+        .type = CPUID_FEATURE_WORD,
+        .cpuid = {
+            .eax = 0xD,
+            .needs_ecx = true,
+            .ecx = 1,
+            .reg = R_EDX
+        },
+    },
     [FEAT_6_EAX] = {
         .type = CPUID_FEATURE_WORD,
         .feat_names = {
@@ -952,7 +980,7 @@ FeatureWordInfo feature_word_info[FEATURE_WORDS] = {
         .cpuid = { .eax = 6, .reg = R_EAX, },
         .tcg_features = TCG_6_EAX_FEATURES,
     },
-    [FEAT_XSAVE_COMP_LO] = {
+    [FEAT_XSAVE_XCR0_LO] = {
         .type = CPUID_FEATURE_WORD,
         .cpuid = {
             .eax = 0xD,
@@ -965,7 +993,7 @@ FeatureWordInfo feature_word_info[FEATURE_WORDS] = {
             XSTATE_OPMASK_MASK | XSTATE_ZMM_Hi256_MASK | XSTATE_Hi16_ZMM_MASK |
             XSTATE_PKRU_MASK,
     },
-    [FEAT_XSAVE_COMP_HI] = {
+    [FEAT_XSAVE_XCR0_HI] = {
         .type = CPUID_FEATURE_WORD,
         .cpuid = {
             .eax = 0xD,
@@ -1382,6 +1410,9 @@ static const X86RegisterInfo32 x86_reg_info_32[CPU_NB_REGS32] = {
 };
 #undef REGISTER
 
+/* CPUID feature bits available in XSS */
+#define CPUID_XSTATE_XSS_MASK    (0)
+
 ExtSaveArea x86_ext_save_areas[XSAVE_STATE_AREA_COUNT] = {
     [XSTATE_FP_BIT] = {
         /* x87 FP state component is always enabled if XSAVE is supported */
@@ -1424,15 +1455,18 @@ ExtSaveArea x86_ext_save_areas[XSAVE_STATE_AREA_COUNT] = {
     },
 };
 
-static uint32_t xsave_area_size(uint64_t mask)
+static uint32_t xsave_area_size(uint64_t mask, bool compacted)
 {
+    uint64_t ret = x86_ext_save_areas[0].size;
+    const ExtSaveArea *esa;
+    uint32_t offset = 0;
     int i;
-    uint64_t ret = 0;
 
-    for (i = 0; i < ARRAY_SIZE(x86_ext_save_areas); i++) {
-        const ExtSaveArea *esa = &x86_ext_save_areas[i];
+    for (i = 2; i < ARRAY_SIZE(x86_ext_save_areas); i++) {
+        esa = &x86_ext_save_areas[i];
         if ((mask >> i) & 1) {
-            ret = MAX(ret, esa->offset + esa->size);
+            offset = compacted ? ret : esa->offset;
+            ret = MAX(ret, offset + esa->size);
         }
     }
     return ret;
@@ -1443,10 +1477,10 @@ static inline bool accel_uses_host_cpuid(void)
     return kvm_enabled() || hvf_enabled();
 }
 
-static inline uint64_t x86_cpu_xsave_components(X86CPU *cpu)
+static inline uint64_t x86_cpu_xsave_xcr0_components(X86CPU *cpu)
 {
-    return ((uint64_t)cpu->env.features[FEAT_XSAVE_COMP_HI]) << 32 |
-           cpu->env.features[FEAT_XSAVE_COMP_LO];
+    return ((uint64_t)cpu->env.features[FEAT_XSAVE_XCR0_HI]) << 32 |
+           cpu->env.features[FEAT_XSAVE_XCR0_LO];
 }
 
 /* Return name of 32-bit register, from a R_* constant */
@@ -1458,6 +1492,12 @@ static const char *get_register_name_32(unsigned int reg)
     return x86_reg_info_32[reg].name;
 }
 
+static inline uint64_t x86_cpu_xsave_xss_components(X86CPU *cpu)
+{
+    return ((uint64_t)cpu->env.features[FEAT_XSAVE_XSS_HI]) << 32 |
+           cpu->env.features[FEAT_XSAVE_XSS_LO];
+}
+
 /*
  * Returns the set of feature flags that are supported and migratable by
  * QEMU, for a given FeatureWord.
@@ -4511,8 +4551,8 @@ static const char *x86_cpu_feature_name(FeatureWord w, int bitnr)
     /* XSAVE components are automatically enabled by other features,
      * so return the original feature name instead
      */
-    if (w == FEAT_XSAVE_COMP_LO || w == FEAT_XSAVE_COMP_HI) {
-        int comp = (w == FEAT_XSAVE_COMP_HI) ? bitnr + 32 : bitnr;
+    if (w == FEAT_XSAVE_XCR0_LO || w == FEAT_XSAVE_XCR0_HI) {
+        int comp = (w == FEAT_XSAVE_XCR0_HI) ? bitnr + 32 : bitnr;
 
         if (comp < ARRAY_SIZE(x86_ext_save_areas) &&
             x86_ext_save_areas[comp].bits) {
@@ -5408,25 +5448,36 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
         }
 
         if (count == 0) {
-            *ecx = xsave_area_size(x86_cpu_xsave_components(cpu));
-            *eax = env->features[FEAT_XSAVE_COMP_LO];
-            *edx = env->features[FEAT_XSAVE_COMP_HI];
+            *ecx = xsave_area_size(x86_cpu_xsave_xcr0_components(cpu), false);
+            *eax = env->features[FEAT_XSAVE_XCR0_LO];
+            *edx = env->features[FEAT_XSAVE_XCR0_HI];
             /*
              * The initial value of xcr0 and ebx == 0, On host without kvm
              * commit 412a3c41(e.g., CentOS 6), the ebx's value always == 0
              * even through guest update xcr0, this will crash some legacy guest
              * (e.g., CentOS 6), So set ebx == ecx to workaroud it.
              */
-            *ebx = kvm_enabled() ? *ecx : xsave_area_size(env->xcr0);
+            *ebx = kvm_enabled() ? *ecx : xsave_area_size(env->xcr0, false);
         } else if (count == 1) {
+            uint64_t xstate = x86_cpu_xsave_xcr0_components(cpu) |
+                              x86_cpu_xsave_xss_components(cpu);
+
             *eax = env->features[FEAT_XSAVE];
+            *ebx = xsave_area_size(xstate, true);
+            *ecx = env->features[FEAT_XSAVE_XSS_LO];
+            *edx = env->features[FEAT_XSAVE_XSS_HI];
         } else if (count < ARRAY_SIZE(x86_ext_save_areas)) {
-            if ((x86_cpu_xsave_components(cpu) >> count) & 1) {
-                const ExtSaveArea *esa = &x86_ext_save_areas[count];
+            const ExtSaveArea *esa = &x86_ext_save_areas[count];
+
+            if (x86_cpu_xsave_xcr0_components(cpu) & (1ULL << count)) {
                 *eax = esa->size;
                 *ebx = esa->offset;
                 *ecx = esa->ecx &
                        (ESA_FEATURE_ALIGN64_MASK | ESA_FEATURE_XFD_MASK);
+            } else if (x86_cpu_xsave_xss_components(cpu) & (1ULL << count)) {
+                *eax = esa->size;
+                *ebx = 0;
+                *ecx = 1;
             }
         }
         break;
@@ -5477,8 +5528,8 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
         } else {
             *eax &= env->features[FEAT_SGX_12_1_EAX];
             *ebx &= 0; /* ebx reserve */
-            *ecx &= env->features[FEAT_XSAVE_COMP_LO];
-            *edx &= env->features[FEAT_XSAVE_COMP_HI];
+            *ecx &= env->features[FEAT_XSAVE_XSS_LO];
+            *edx &= env->features[FEAT_XSAVE_XSS_HI];
 
             /* FP and SSE are always allowed regardless of XSAVE/XCR0. */
             *ecx |= XSTATE_FP_MASK | XSTATE_SSE_MASK;
@@ -5874,6 +5925,9 @@ static void x86_cpu_reset(DeviceState *dev)
     }
     for (i = 2; i < ARRAY_SIZE(x86_ext_save_areas); i++) {
         const ExtSaveArea *esa = &x86_ext_save_areas[i];
+        if (!((1 << i) & CPUID_XSTATE_XCR0_MASK)) {
+            continue;
+        }
         if (env->features[esa->feature] & esa->bits) {
             xcr0 |= 1ull << i;
         }
@@ -5988,8 +6042,8 @@ static void x86_cpu_enable_xsave_components(X86CPU *cpu)
     static bool request_perm;
 
     if (!(env->features[FEAT_1_ECX] & CPUID_EXT_XSAVE)) {
-        env->features[FEAT_XSAVE_COMP_LO] = 0;
-        env->features[FEAT_XSAVE_COMP_HI] = 0;
+        env->features[FEAT_XSAVE_XCR0_LO] = 0;
+        env->features[FEAT_XSAVE_XCR0_HI] = 0;
         return;
     }
 
@@ -6007,8 +6061,10 @@ static void x86_cpu_enable_xsave_components(X86CPU *cpu)
         request_perm = true;
     }
 
-    env->features[FEAT_XSAVE_COMP_LO] = mask;
-    env->features[FEAT_XSAVE_COMP_HI] = mask >> 32;
+    env->features[FEAT_XSAVE_XCR0_LO] = mask & CPUID_XSTATE_XCR0_MASK;
+    env->features[FEAT_XSAVE_XCR0_HI] = mask >> 32;
+    env->features[FEAT_XSAVE_XSS_LO] = mask & CPUID_XSTATE_XSS_MASK;
+    env->features[FEAT_XSAVE_XSS_HI] = mask >> 32;
 }
 
 /***** Steps involved on loading and filtering CPUID data
diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index 6730df5..453b80e 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -568,6 +568,14 @@ typedef enum X86Seg {
 #define ESA_FEATURE_XFD_MASK            (1U << ESA_FEATURE_XFD_BIT)
 
 
+/* CPUID feature bits available in XCR0 */
+#define CPUID_XSTATE_XCR0_MASK  (XSTATE_FP_MASK | XSTATE_SSE_MASK | \
+                                 XSTATE_YMM_MASK | XSTATE_BNDREGS_MASK | \
+                                 XSTATE_BNDCSR_MASK | XSTATE_OPMASK_MASK | \
+                                 XSTATE_ZMM_Hi256_MASK | \
+                                 XSTATE_Hi16_ZMM_MASK | XSTATE_PKRU_MASK | \
+                                 XSTATE_XTILE_CFG_MASK | XSTATE_XTILE_DATA_MASK)
+
 /* CPUID feature words */
 typedef enum FeatureWord {
     FEAT_1_EDX,         /* CPUID[1].EDX */
@@ -586,8 +594,8 @@ typedef enum FeatureWord {
     FEAT_SVM,           /* CPUID[8000_000A].EDX */
     FEAT_XSAVE,         /* CPUID[EAX=0xd,ECX=1].EAX */
     FEAT_6_EAX,         /* CPUID[6].EAX */
-    FEAT_XSAVE_COMP_LO, /* CPUID[EAX=0xd,ECX=0].EAX */
-    FEAT_XSAVE_COMP_HI, /* CPUID[EAX=0xd,ECX=0].EDX */
+    FEAT_XSAVE_XCR0_LO, /* CPUID[EAX=0xd,ECX=0].EAX */
+    FEAT_XSAVE_XCR0_HI, /* CPUID[EAX=0xd,ECX=0].EDX */
     FEAT_ARCH_CAPABILITIES,
     FEAT_CORE_CAPABILITY,
     FEAT_PERF_CAPABILITIES,
@@ -604,6 +612,8 @@ typedef enum FeatureWord {
     FEAT_SGX_12_0_EAX,  /* CPUID[EAX=0x12,ECX=0].EAX (SGX) */
     FEAT_SGX_12_0_EBX,  /* CPUID[EAX=0x12,ECX=0].EBX (SGX MISCSELECT[31:0]) */
     FEAT_SGX_12_1_EAX,  /* CPUID[EAX=0x12,ECX=1].EAX (SGX ATTRIBUTES[31:0]) */
+    FEAT_XSAVE_XSS_LO,     /* CPUID[EAX=0xd,ECX=1].ECX */
+    FEAT_XSAVE_XSS_HI,     /* CPUID[EAX=0xd,ECX=1].EDX */
     FEATURE_WORDS,
 } FeatureWord;