[Qemu-devel] [PATCH 2/2] target-i386: Intel MPX support

[Liu, Jinsong]

>From aac033473bc88befe39a9add99820c0a7118ac90 Mon Sep 17 00:00:00 2001
From: root <address@hidden(none)>
Date: Fri, 22 Nov 2013 00:24:35 +0800
Subject: [PATCH 2/2] target-i386: Intel MPX support

Expose cpuid leaf (0xd, 3) and (0xd, 4) to guest.
Fix ebx and re-calculate ecx of cpuid leaf (0xd, 0).

Signed-off-by: Liu Jinsong <address@hidden>
---
 target-i386/cpu.c |   34 ++++++++++++++++++++++++++--------
 target-i386/cpu.h |    1 +
 2 files changed, 27 insertions(+), 8 deletions(-)

diff --git a/target-i386/cpu.c b/target-i386/cpu.c
index 544b57f..7d04f28 100644
--- a/target-i386/cpu.c
+++ b/target-i386/cpu.c
@@ -330,12 +330,12 @@ X86RegisterInfo32 x86_reg_info_32[CPU_NB_REGS32] = {

 typedef struct ExtSaveArea {
     uint32_t feature, bits;
-    uint32_t offset, size;
 } ExtSaveArea;

 static const ExtSaveArea ext_save_areas[] = {
-    [2] = { .feature = FEAT_1_ECX, .bits = CPUID_EXT_AVX,
-            .offset = 0x240, .size = 0x100 },
+    [2] = { .feature = FEAT_1_ECX, .bits = CPUID_EXT_AVX },
+    [3] = { .feature = FEAT_7_0_EBX, .bits = CPUID_7_0_EBX_MPX },
+    [4] = { .feature = FEAT_7_0_EBX, .bits = CPUID_7_0_EBX_MPX },
 };

 const char *get_register_name_32(unsigned int reg)
@@ -2204,9 +2204,11 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, 
uint32_t count,
             ((uint64_t)kvm_arch_get_supported_cpuid(s, 0xd, 0, R_EDX) << 32);

         if (count == 0) {
-            *ecx = 0x240;
+            *ebx = *ecx = 0x240;
             for (i = 2; i < ARRAY_SIZE(ext_save_areas); i++) {
+                uint32_t offset, size;
                 const ExtSaveArea *esa = &ext_save_areas[i];
+
                 if ((env->features[esa->feature] & esa->bits) == esa->bits &&
                     (kvm_mask & (1 << i)) != 0) {
                     if (i < 32) {
@@ -2214,19 +2216,35 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, 
uint32_t count,
                     } else {
                         *edx |= 1 << (i - 32);
                     }
-                    *ecx = MAX(*ecx, esa->offset + esa->size);
+
+                    size = kvm_arch_get_supported_cpuid(s, 0xd, i, R_EAX);
+                    offset = kvm_arch_get_supported_cpuid(s, 0xd, i, R_EBX);
+                    *ecx = MAX(*ecx, offset + size);
+
+                    /*
+                     * EBX here just in order to
+                     * 1. keep compatible with old qemu version, take AVX
+                     *    into account;
+                     * 2. keep compatible with old kernel version. Currently
+                     *    KVM has bug when expose cpuid 0xd to guest (include
+                     *    static value when guest booting and dynamic value
+                     *    when guest enables XCR0 features. EBX here can
+                     *    co-work with old buggy and new updated KVM, keep
+                     *    same value independent to CPU and kernel version.
+                     */
+                    if (i == 2)
+                        *ebx = MAX(*ebx, offset + size);
                 }
             }
             *eax |= kvm_mask & (XSTATE_FP | XSTATE_SSE);
-            *ebx = *ecx;
         } else if (count == 1) {
             *eax = kvm_arch_get_supported_cpuid(s, 0xd, 1, R_EAX);
         } else if (count < ARRAY_SIZE(ext_save_areas)) {
             const ExtSaveArea *esa = &ext_save_areas[count];
             if ((env->features[esa->feature] & esa->bits) == esa->bits &&
                 (kvm_mask & (1 << count)) != 0) {
-                *eax = esa->size;
-                *ebx = esa->offset;
+                *eax = kvm_arch_get_supported_cpuid(s, 0xd, count, R_EAX);
+                *ebx = kvm_arch_get_supported_cpuid(s, 0xd, count, R_EBX);
             }
         }
         break;
diff --git a/target-i386/cpu.h b/target-i386/cpu.h
index ea373e8..9a838d1 100644
--- a/target-i386/cpu.h
+++ b/target-i386/cpu.h
@@ -545,6 +545,7 @@ typedef uint32_t FeatureWordArray[FEATURE_WORDS];
 #define CPUID_7_0_EBX_ERMS     (1 << 9)
 #define CPUID_7_0_EBX_INVPCID  (1 << 10)
 #define CPUID_7_0_EBX_RTM      (1 << 11)
+#define CPUID_7_0_EBX_MPX      (1 << 14)
 #define CPUID_7_0_EBX_RDSEED   (1 << 18)
 #define CPUID_7_0_EBX_ADX      (1 << 19)
 #define CPUID_7_0_EBX_SMAP     (1 << 20)
--
1.7.1