[RFC PATCH 4/7] x86: Add XFD faulting bit for state components

[Yang Zhong]

From: Jing Liu <jing2....@intel.com>

Intel introduces XFD faulting mechanism for extended
XSAVE features to dynamically enable the features in
runtime. If CPUID (EAX=0Dh, ECX=n, n>1).ECX[2] is set
as 1, it indicates support for XFD faulting of this
state component.

Signed-off-by: Jing Liu <jing2....@intel.com>
Signed-off-by: Yang Zhong <yang.zh...@intel.com>
---
 target/i386/cpu.h         | 2 +-
 target/i386/cpu.c         | 2 +-
 target/i386/kvm/kvm-cpu.c | 1 +
 3 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index 79023fe723..22f7ff40a6 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -1375,7 +1375,7 @@ QEMU_BUILD_BUG_ON(sizeof(XSaveXTILE_DATA) != 0x2000);
 typedef struct ExtSaveArea {
     uint32_t feature, bits;
     uint32_t offset, size;
-    uint32_t need_align;
+    uint32_t need_align, support_xfd;
 } ExtSaveArea;
 
 #define XSAVE_STATE_AREA_COUNT (XSTATE_XTILE_DATA_BIT + 1)
diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index dd2c919c33..1adc3f0f99 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -5495,7 +5495,7 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, 
uint32_t count,
                 const ExtSaveArea *esa = &x86_ext_save_areas[count];
                 *eax = esa->size;
                 *ebx = esa->offset;
-                *ecx = esa->need_align << 1;
+                *ecx = (esa->need_align << 1) | (esa->support_xfd << 2);
             }
         }
         break;
diff --git a/target/i386/kvm/kvm-cpu.c b/target/i386/kvm/kvm-cpu.c
index 6c4c1c6f9d..3b3c203f11 100644
--- a/target/i386/kvm/kvm-cpu.c
+++ b/target/i386/kvm/kvm-cpu.c
@@ -108,6 +108,7 @@ static void kvm_cpu_xsave_init(void)
 
             uint32_t ecx = kvm_arch_get_supported_cpuid(s, 0xd, i, R_ECX);
             esa->need_align = ecx & (1u << 1) ? 1 : 0;
+            esa->support_xfd = ecx & (1u << 2) ? 1 : 0;
         }
     }
 }