i386/cpu: Make ExtSaveArea store an array of dependencies

Some XSAVE components depend on multiple features. For example, Opmask/
ZMM_Hi256/Hi16_ZMM depend on avx512f OR avx10, and for CET (which will
be supported later), cet_u/cet_s will depend on shstk OR ibt.

Although previously there's the special check for the dependencies of
AVX512F OR AVX10 on their respective XSAVE components (in
cpuid_has_xsave_feature()), to make the code more general and avoid
adding more special cases, make ExtSaveArea store a features array
instead of a single feature, so that it can describe multiple
dependencies.

Tested-by: Farrah Chen <farrah.chen@intel.com>
Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
Link: https://lore.kernel.org/r/20251211060801.3600039-5-zhao1.liu@intel.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index de4e5c57746a093aadc0d87839e0757148fdf776..367396a216e5d8bef78e961c5b89fb9c156a9dc2 100644 (file)
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -2020,53 +2020,77 @@ static const X86RegisterInfo32 x86_reg_info_32[CPU_NB_REGS32] = {
 ExtSaveArea x86_ext_save_areas[XSAVE_STATE_AREA_COUNT] = {
     [XSTATE_FP_BIT] = {
         /* x87 FP state component is always enabled if XSAVE is supported */
-        .feature = FEAT_1_ECX, .bits = CPUID_EXT_XSAVE,
         .size = sizeof(X86LegacyXSaveArea) + sizeof(X86XSaveHeader),
+        .features = {
+            { FEAT_1_ECX,           CPUID_EXT_XSAVE },
+        },
     },
     [XSTATE_SSE_BIT] = {
         /* SSE state component is always enabled if XSAVE is supported */
-        .feature = FEAT_1_ECX, .bits = CPUID_EXT_XSAVE,
         .size = sizeof(X86LegacyXSaveArea) + sizeof(X86XSaveHeader),
+        .features = {
+            { FEAT_1_ECX,           CPUID_EXT_XSAVE },
+        },
     },
     [XSTATE_YMM_BIT] = {
-        .feature = FEAT_1_ECX, .bits = CPUID_EXT_AVX,
         .size = sizeof(XSaveAVX),
+        .features = {
+            { FEAT_1_ECX,           CPUID_EXT_AVX },
+        },
     },
     [XSTATE_BNDREGS_BIT] = {
-        .feature = FEAT_7_0_EBX, .bits = CPUID_7_0_EBX_MPX,
         .size = sizeof(XSaveBNDREG),
+        .features = {
+            { FEAT_7_0_EBX,         CPUID_7_0_EBX_MPX },
+        },
     },
     [XSTATE_BNDCSR_BIT] = {
-        .feature = FEAT_7_0_EBX, .bits = CPUID_7_0_EBX_MPX,
         .size = sizeof(XSaveBNDCSR),
+        .features = {
+            { FEAT_7_0_EBX,         CPUID_7_0_EBX_MPX },
+        },
     },
     [XSTATE_OPMASK_BIT] = {
-        .feature = FEAT_7_0_EBX, .bits = CPUID_7_0_EBX_AVX512F,
         .size = sizeof(XSaveOpmask),
+        .features = {
+            { FEAT_7_0_EBX,         CPUID_7_0_EBX_AVX512F },
+        },
     },
     [XSTATE_ZMM_Hi256_BIT] = {
-        .feature = FEAT_7_0_EBX, .bits = CPUID_7_0_EBX_AVX512F,
         .size = sizeof(XSaveZMM_Hi256),
+        .features = {
+            { FEAT_7_0_EBX,         CPUID_7_0_EBX_AVX512F },
+        },
     },
     [XSTATE_Hi16_ZMM_BIT] = {
-        .feature = FEAT_7_0_EBX, .bits = CPUID_7_0_EBX_AVX512F,
         .size = sizeof(XSaveHi16_ZMM),
+        .features = {
+            { FEAT_7_0_EBX,         CPUID_7_0_EBX_AVX512F },
+        },
     },
     [XSTATE_PKRU_BIT] = {
-        .feature = FEAT_7_0_ECX, .bits = CPUID_7_0_ECX_PKU,
         .size = sizeof(XSavePKRU),
+        .features = {
+            { FEAT_7_0_ECX,         CPUID_7_0_ECX_PKU },
+        },
     },
     [XSTATE_ARCH_LBR_BIT] = {
-        .feature = FEAT_7_0_EDX, .bits = CPUID_7_0_EDX_ARCH_LBR,
         .size = sizeof(XSaveArchLBR),
+        .features = {
+            { FEAT_7_0_EDX,         CPUID_7_0_EDX_ARCH_LBR },
+        },
     },
     [XSTATE_XTILE_CFG_BIT] = {
-        .feature = FEAT_7_0_EDX, .bits = CPUID_7_0_EDX_AMX_TILE,
         .size = sizeof(XSaveXTILECFG),
+        .features = {
+            { FEAT_7_0_EDX,         CPUID_7_0_EDX_AMX_TILE },
+        },
     },
     [XSTATE_XTILE_DATA_BIT] = {
-        .feature = FEAT_7_0_EDX, .bits = CPUID_7_0_EDX_AMX_TILE,
         .size = sizeof(XSaveXTILEDATA),
+        .features = {
+            { FEAT_7_0_EDX,         CPUID_7_0_EDX_AMX_TILE },
+        },
     },
 };
 
@@ -7131,16 +7155,24 @@ static inline void feat2prop(char *s)
 static const char *x86_cpu_feature_name(FeatureWord w, int bitnr)
 {
     const char *name;
-    /* XSAVE components are automatically enabled by other features,
+    /*
+     * XSAVE components are automatically enabled by other features,
      * so return the original feature name instead
      */
     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) {
-            w = x86_ext_save_areas[comp].feature;
-            bitnr = ctz32(x86_ext_save_areas[comp].bits);
+        if (comp < ARRAY_SIZE(x86_ext_save_areas)) {
+            /*
+             * Present the first feature as the default.
+             * FIXME: select and present the one which is actually enabled
+             * among multiple dependencies.
+             */
+            const FeatureMask *fm = &x86_ext_save_areas[comp].features[0];
+            if (fm->mask) {
+                w = fm->index;
+                bitnr = ctz32(fm->mask);
+            }
         }
     }
 
@@ -8610,11 +8642,15 @@ static bool cpuid_has_xsave_feature(CPUX86State *env, const ExtSaveArea *esa)
         return false;
     }
 
-    if (env->features[esa->feature] & esa->bits) {
-        return true;
+    for (int i = 0; i < ARRAY_SIZE(esa->features); i++) {
+        if (env->features[esa->features[i].index] & esa->features[i].mask) {
+            return true;
+        }
     }
-    if (esa->feature == FEAT_7_0_EBX && esa->bits == CPUID_7_0_EBX_AVX512F
-        && (env->features[FEAT_7_1_EDX] & CPUID_7_1_EDX_AVX10)) {
+
+    if (esa->features[0].index == FEAT_7_0_EBX &&
+        esa->features[0].mask == CPUID_7_0_EBX_AVX512F &&
+        (env->features[FEAT_7_1_EDX] & CPUID_7_1_EDX_AVX10)) {
         return true;
     }
 

diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index a183394eca7f182c9770bde97664308b16f3cc29..3d74afc5a8e739ca420e09d3764ce7944dad4f1c 100644 (file)
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -1769,9 +1769,16 @@ QEMU_BUILD_BUG_ON(sizeof(XSaveXTILECFG) != 0x40);
 QEMU_BUILD_BUG_ON(sizeof(XSaveXTILEDATA) != 0x2000);
 
 typedef struct ExtSaveArea {
-    uint32_t feature, bits;
     uint32_t offset, size;
     uint32_t ecx;
+    /*
+     * The dependencies in the array work as OR relationships, which
+     * means having just one of those features is enough.
+     *
+     * At most two features are sharing the same xsave area.
+     * Number of features can be adjusted if necessary.
+     */
+    const FeatureMask features[2];
 } ExtSaveArea;
 
 #define XSAVE_STATE_AREA_COUNT (XSTATE_XTILE_DATA_BIT + 1)