[Xen-devel] [PATCH v2 13/16] x86emul: support XSETBV

["Jan Beulich" <JBeulich@xxxxxxxx>]

This is a prereq for switching PV privileged op emulation to the
generic instruction emulator. Since handle_xsetbv() is already capable
of dealing with all guest kinds, avoid introducing another hook here.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
v2: Explicitly generate #UD when vex.pfx is non-zero.

--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -4178,6 +4178,23 @@ x86_emulate(
 
         switch( modrm )
         {
+#ifdef __XEN__
+        case 0xd1: /* xsetbv */
+        {
+            unsigned long cr4;
+
+            generate_exception_if(vex.pfx, EXC_UD, -1);
+            if ( !ops->read_cr || ops->read_cr(4, &cr4, ctxt) != X86EMUL_OKAY )
+                cr4 = 0;
+            generate_exception_if(!(cr4 & X86_CR4_OSXSAVE), EXC_UD, -1);
+            generate_exception_if(!mode_ring0() ||
+                                  handle_xsetbv(_regs._ecx,
+                                                _regs._eax | (_regs.rdx << 
32)),
+                                  EXC_GP, 0);
+            goto no_writeback;
+        }
+#endif
+
         case 0xdf: /* invlpga */
             generate_exception_if(!in_protmode(ctxt, ops), EXC_UD, -1);
             generate_exception_if(!mode_ring0(), EXC_GP, 0);

Attachment: x86emul-XSETBV.patch
Description: Text document

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