diff mbox

[v2,13/16] x86emul: support XSETBV

Message ID 57EB98AC0200007800113207@prv-mh.provo.novell.com (mailing list archive)
State New, archived
Headers show

Commit Message

Jan Beulich Sept. 28, 2016, 8:17 a.m. UTC 
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@suse.com>
---
v2: Explicitly generate #UD when vex.pfx is non-zero.
x86emul: support XSETBV

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@suse.com>
---
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);

Comments

Andrew Cooper Sept. 29, 2016, 8:45 p.m. UTC | #1 
On 28/09/16 09:17, Jan Beulich wrote:
> 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@suse.com>

Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Jan Beulich Sept. 30, 2016, 8:05 a.m. UTC | #2 
>>> On 29.09.16 at 22:45, <andrew.cooper3@citrix.com> wrote:
> On 28/09/16 09:17, Jan Beulich wrote:
>> 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@suse.com>
> 
> Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>

Thanks, but this needs a v3 - I didn't notice until my pre-commit
build check that it needs several hunks from "x86emul: conditionally
clear BNDn for branches" moved here (in order to facilitate
including asm/xstate.h in xen/arch/x86/x86_emulate.c.

Jan
diff mbox

Patch

--- 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);