[Xen-devel] [PATCH 4/4] x86/svm: Use named (bit)fields for task switch exit info

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

Introduce vmcb.e1.* and vmcb.e2.* to provide names to fields in exitinfo{1,2}
respectively.  Implement the task switch names for now, and clean up the
TASK_SWITCH handler.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Wei Liu <wl@xxxxxxx>
CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
 xen/arch/x86/hvm/svm/svm.c         | 22 ++++++----------------
 xen/include/asm-x86/hvm/svm/vmcb.h | 26 ++++++++++++++++++++++++--
 2 files changed, 30 insertions(+), 18 deletions(-)

diff --git a/xen/arch/x86/hvm/svm/svm.c b/xen/arch/x86/hvm/svm/svm.c
index 263ae03bfd..6c68bcee59 100644
--- a/xen/arch/x86/hvm/svm/svm.c
+++ b/xen/arch/x86/hvm/svm/svm.c
@@ -2746,10 +2746,7 @@ void svm_vmexit_handler(struct cpu_user_regs *regs)
         svm_vmexit_do_invalidate_cache(regs, exit_reason == VMEXIT_INVD);
         break;
 
-    case VMEXIT_TASK_SWITCH: {
-        enum hvm_task_switch_reason reason;
-        int32_t errcode = -1;
-
+    case VMEXIT_TASK_SWITCH:
         /*
          * All TASK_SWITCH intercepts have fault-like semantics.  NRIP is
          * never provided, even for instruction-induced task switches, but we
@@ -2795,19 +2792,12 @@ void svm_vmexit_handler(struct cpu_user_regs *regs)
         if ( insn_len < 0 && (insn_len = svm_get_task_switch_insn_len()) == 0 )
             goto crash_or_fault;
 
-        if ( (vmcb->exitinfo2 >> 36) & 1 )
-            reason = TSW_iret;
-        else if ( (vmcb->exitinfo2 >> 38) & 1 )
-            reason = TSW_jmp;
-        else
-            reason = TSW_call_or_int;
-        if ( (vmcb->exitinfo2 >> 44) & 1 )
-            errcode = (uint32_t)vmcb->exitinfo2;
-
-        hvm_task_switch(vmcb->exitinfo1, reason, errcode, insn_len,
-                        (vmcb->exitinfo2 & (1ul << 48)) ? X86_EFLAGS_RF : 0);
+        hvm_task_switch(vmcb->e1.task_switch.sel,
+                        vmcb->e2.task_switch.iret ? TSW_iret :
+                        vmcb->e2.task_switch.jmp  ? TSW_jmp : TSW_call_or_int,
+                        vmcb->e2.task_switch.ev ? vmcb->e2.task_switch.ec : -1,
+                        insn_len, vmcb->e2.task_switch.rf ? X86_EFLAGS_RF : 0);
         break;
-    }
 
     case VMEXIT_CPUID:
         if ( (insn_len = svm_get_insn_len(v, INSTR_CPUID)) == 0 )
diff --git a/xen/include/asm-x86/hvm/svm/vmcb.h 
b/xen/include/asm-x86/hvm/svm/vmcb.h
index fc67a88660..02b5e86b49 100644
--- a/xen/include/asm-x86/hvm/svm/vmcb.h
+++ b/xen/include/asm-x86/hvm/svm/vmcb.h
@@ -418,8 +418,30 @@ struct vmcb_struct {
     vintr_t _vintr;             /* offset 0x60 - cleanbit 3 */
     u64 interrupt_shadow;       /* offset 0x68 */
     u64 exitcode;               /* offset 0x70 */
-    u64 exitinfo1;              /* offset 0x78 */
-    u64 exitinfo2;              /* offset 0x80 */
+    union {
+        u64 exitinfo1;          /* offset 0x78 */
+        union {
+            struct {
+                uint16_t sel;
+            } task_switch;
+        } e1;
+    };
+    union {
+        u64 exitinfo2;          /* offset 0x80 */
+        union {
+            struct {
+                uint32_t ec;
+                uint32_t :4;
+                bool     iret:1;
+                uint32_t :1;
+                bool     jmp:1;
+                uint32_t :5;
+                bool     ev:1;
+                uint32_t :3;
+                bool     rf:1;
+            } task_switch;
+        } e2;
+    };
     intinfo_t exitintinfo;      /* offset 0x88 */
     u64 _np_enable;             /* offset 0x90 - cleanbit 4 */
     u64 res08[2];
-- 
2.11.0


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