svm: add bit definitions for SVM DecodeAssist

Chapter 15.33 of recent APM Vol.2 manuals describe some additions
to SVM called DecodeAssist. Add the newly added fields to the VMCB
structure and name the associated CPUID bit.

Signed-off-by: Andre Przywara <andre.przywara@amd.com>

xen/arch/x86/hvm/svm/svm.c

@@ -1000,6 +1000,7 @@ struct hvm_function_table * __init start_svm(void)
     P(cpu_has_svm_lbrv, "Last Branch Record (LBR) Virtualisation");
     P(cpu_has_svm_nrips, "Next-RIP Saved on #VMEXIT");
     P(cpu_has_svm_cleanbits, "VMCB Clean Bits");
+    P(cpu_has_svm_decode, "DecodeAssists");
     P(cpu_has_pause_filter, "Pause-Intercept Filter");
 #undef P
 

xen/include/asm-x86/hvm/svm/svm.h

@@ -90,6 +90,7 @@ extern u32 svm_feature_flags;
 #define cpu_has_svm_svml      cpu_has_svm_feature(SVM_FEATURE_SVML)
 #define cpu_has_svm_nrips     cpu_has_svm_feature(SVM_FEATURE_NRIPS)
 #define cpu_has_svm_cleanbits cpu_has_svm_feature(SVM_FEATURE_VMCBCLEAN)
+#define cpu_has_svm_decode    cpu_has_svm_feature(SVM_FEATURE_DECODEASSISTS)
 #define cpu_has_pause_filter  cpu_has_svm_feature(SVM_FEATURE_PAUSEFILTER)
 
 #define SVM_PAUSEFILTER_INIT    3000

xen/include/asm-x86/hvm/svm/vmcb.h

@@ -435,7 +435,9 @@ struct vmcb_struct {
     vmcbcleanbits_t cleanbits;  /* offset 0xC0 */
     u32 res09;                  /* offset 0xC4 */
     u64 nextrip;                /* offset 0xC8 */
-    u64 res10a[102];            /* offset 0xD0 pad to save area */
+    u8  guest_ins_len;          /* offset 0xD0 */
+    u8  guest_ins[15];          /* offset 0xD1 */
+    u64 res10a[100];            /* offset 0xE0 pad to save area */
 
     svm_segment_register_t es;  /* offset 1024 - cleanbit 8 */
     svm_segment_register_t cs;  /* cleanbit 8 */