[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[Xen-devel] [PATCH] x86-64: emulation support for cmpxchg16b



With the x86 instruction emulator no pretty complete, I'd like to
re-submit this patch to support cmpxchg16b on x86-64 and at once rename
the underlying emulator callback function pointer (making clear that if
implemented, it is to operate on two longs rather than two 32-bit
values). At the same time it fixes an apparently wrong emulator context
initialization in the shadow code.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>

Index: 2008-04-15/tools/tests/test_x86_emulator.c
===================================================================
--- 2008-04-15.orig/tools/tests/test_x86_emulator.c     2008-04-01 
11:10:21.000000000 +0200
+++ 2008-04-15/tools/tests/test_x86_emulator.c  2008-04-15 08:48:15.000000000 
+0200
@@ -74,7 +74,7 @@ static int cmpxchg(
     return X86EMUL_OKAY;
 }
 
-static int cmpxchg8b(
+static int cmpxchg2(
     unsigned int seg,
     unsigned long offset,
     unsigned long old_lo,
@@ -94,7 +94,7 @@ static struct x86_emulate_ops emulops = 
     .insn_fetch = read,
     .write      = write,
     .cmpxchg    = cmpxchg,
-    .cmpxchg8b  = cmpxchg8b
+    .cmpxchg2   = cmpxchg2
 };
 
 int main(int argc, char **argv)
Index: 2008-04-15/tools/tests/x86_emulate.c
===================================================================
--- 2008-04-15.orig/tools/tests/x86_emulate.c   2008-04-01 11:10:21.000000000 
+0200
+++ 2008-04-15/tools/tests/x86_emulate.c        2008-04-15 08:48:15.000000000 
+0200
@@ -3,6 +3,8 @@
 #include <string.h>
 #include <public/xen.h>
 
+#define cpu_has_cmpxchg16b (sizeof(long) == 8)
+
 #include "x86_emulate/x86_emulate.h"
 
 #define __emulate_fpu_insn(_op)                 \
Index: 2008-04-15/xen/arch/x86/mm.c
===================================================================
--- 2008-04-15.orig/xen/arch/x86/mm.c   2008-04-11 14:48:16.000000000 +0200
+++ 2008-04-15/xen/arch/x86/mm.c        2008-04-15 08:48:15.000000000 +0200
@@ -3635,6 +3635,7 @@ static int ptwr_emulated_cmpxchg(
         container_of(ctxt, struct ptwr_emulate_ctxt, ctxt));
 }
 
+#ifdef __i386__
 static int ptwr_emulated_cmpxchg8b(
     enum x86_segment seg,
     unsigned long offset,
@@ -3650,13 +3651,16 @@ static int ptwr_emulated_cmpxchg8b(
         offset, ((u64)old_hi << 32) | old, ((u64)new_hi << 32) | new, 8, 1,
         container_of(ctxt, struct ptwr_emulate_ctxt, ctxt));
 }
+#else
+#define ptwr_emulated_cmpxchg8b NULL
+#endif
 
 static struct x86_emulate_ops ptwr_emulate_ops = {
     .read       = ptwr_emulated_read,
     .insn_fetch = ptwr_emulated_read,
     .write      = ptwr_emulated_write,
     .cmpxchg    = ptwr_emulated_cmpxchg,
-    .cmpxchg8b  = ptwr_emulated_cmpxchg8b
+    .cmpxchg2   = ptwr_emulated_cmpxchg8b
 };
 
 /* Write page fault handler: check if guest is trying to modify a PTE. */
Index: 2008-04-15/xen/arch/x86/mm/shadow/common.c
===================================================================
--- 2008-04-15.orig/xen/arch/x86/mm/shadow/common.c     2008-04-11 
14:48:16.000000000 +0200
+++ 2008-04-15/xen/arch/x86/mm/shadow/common.c  2008-04-15 08:48:15.000000000 
+0200
@@ -262,6 +262,7 @@ hvm_emulate_cmpxchg(enum x86_segment seg
         v, addr, old, new, bytes, sh_ctxt);
 }
 
+#ifdef __i386__
 static int 
 hvm_emulate_cmpxchg8b(enum x86_segment seg,
                       unsigned long offset,
@@ -288,13 +289,16 @@ hvm_emulate_cmpxchg8b(enum x86_segment s
     return v->arch.paging.mode->shadow.x86_emulate_cmpxchg8b(
         v, addr, old_lo, old_hi, new_lo, new_hi, sh_ctxt);
 }
+#else
+#define hvm_emulate_cmpxchg8b NULL
+#endif
 
 static struct x86_emulate_ops hvm_shadow_emulator_ops = {
     .read       = hvm_emulate_read,
     .insn_fetch = hvm_emulate_insn_fetch,
     .write      = hvm_emulate_write,
     .cmpxchg    = hvm_emulate_cmpxchg,
-    .cmpxchg8b  = hvm_emulate_cmpxchg8b,
+    .cmpxchg2   = hvm_emulate_cmpxchg8b,
 };
 
 static int
@@ -352,6 +356,7 @@ pv_emulate_cmpxchg(enum x86_segment seg,
         v, offset, old, new, bytes, sh_ctxt);
 }
 
+#ifdef __i386__
 static int 
 pv_emulate_cmpxchg8b(enum x86_segment seg,
                      unsigned long offset,
@@ -369,13 +374,16 @@ pv_emulate_cmpxchg8b(enum x86_segment se
     return v->arch.paging.mode->shadow.x86_emulate_cmpxchg8b(
         v, offset, old_lo, old_hi, new_lo, new_hi, sh_ctxt);
 }
+#else
+#define pv_emulate_cmpxchg8b NULL
+#endif
 
 static struct x86_emulate_ops pv_shadow_emulator_ops = {
     .read       = pv_emulate_read,
     .insn_fetch = pv_emulate_read,
     .write      = pv_emulate_write,
     .cmpxchg    = pv_emulate_cmpxchg,
-    .cmpxchg8b  = pv_emulate_cmpxchg8b,
+    .cmpxchg2   = pv_emulate_cmpxchg8b,
 };
 
 struct x86_emulate_ops *shadow_init_emulation(
@@ -390,7 +398,12 @@ struct x86_emulate_ops *shadow_init_emul
 
     if ( !is_hvm_vcpu(v) )
     {
+#ifndef CONFIG_COMPAT
         sh_ctxt->ctxt.addr_size = sh_ctxt->ctxt.sp_size = BITS_PER_LONG;
+#else
+        sh_ctxt->ctxt.addr_size = sh_ctxt->ctxt.sp_size =
+            !is_pv_32on64_vcpu(v) ? BITS_PER_LONG : COMPAT_BITS_PER_LONG;
+#endif
         return &pv_shadow_emulator_ops;
     }
 
Index: 2008-04-15/xen/arch/x86/mm/shadow/multi.c
===================================================================
--- 2008-04-15.orig/xen/arch/x86/mm/shadow/multi.c      2008-04-01 
14:20:52.000000000 +0200
+++ 2008-04-15/xen/arch/x86/mm/shadow/multi.c   2008-04-15 08:48:15.000000000 
+0200
@@ -4432,7 +4432,8 @@ sh_x86_emulate_cmpxchg(struct vcpu *v, u
     return rv;
 }
 
-int
+#ifdef __i386__
+static int
 sh_x86_emulate_cmpxchg8b(struct vcpu *v, unsigned long vaddr, 
                           unsigned long old_lo, unsigned long old_hi,
                           unsigned long new_lo, unsigned long new_hi,
@@ -4465,6 +4466,7 @@ sh_x86_emulate_cmpxchg8b(struct vcpu *v,
     shadow_unlock(v->domain);
     return rv;
 }
+#endif
 
 
 /**************************************************************************/
@@ -4738,7 +4740,9 @@ struct paging_mode sh_paging_mode = {
     .shadow.detach_old_tables      = sh_detach_old_tables,
     .shadow.x86_emulate_write      = sh_x86_emulate_write,
     .shadow.x86_emulate_cmpxchg    = sh_x86_emulate_cmpxchg,
+#ifdef __i386__
     .shadow.x86_emulate_cmpxchg8b  = sh_x86_emulate_cmpxchg8b,
+#endif
     .shadow.make_monitor_table     = sh_make_monitor_table,
     .shadow.destroy_monitor_table  = sh_destroy_monitor_table,
 #if SHADOW_OPTIMIZATIONS & SHOPT_WRITABLE_HEURISTIC
Index: 2008-04-15/xen/arch/x86/x86_emulate/x86_emulate.c
===================================================================
--- 2008-04-15.orig/xen/arch/x86/x86_emulate/x86_emulate.c      2008-04-01 
11:10:21.000000000 +0200
+++ 2008-04-15/xen/arch/x86/x86_emulate/x86_emulate.c   2008-04-15 
08:48:15.000000000 +0200
@@ -3346,60 +3346,64 @@ x86_emulate(
         src.val = x86_seg_gs;
         goto pop_seg;
 
-    case 0xc7: /* Grp9 (cmpxchg8b) */
-#if defined(__i386__)
-    {
-        unsigned long old_lo, old_hi;
+    case 0xc7: /* Grp9 (cmpxchg{8,16}b) */
         generate_exception_if((modrm_reg & 7) != 1, EXC_UD, -1);
         generate_exception_if(ea.type != OP_MEM, EXC_UD, -1);
-        if ( (rc = ops->read(ea.mem.seg, ea.mem.off+0, &old_lo, 4, ctxt)) ||
-             (rc = ops->read(ea.mem.seg, ea.mem.off+4, &old_hi, 4, ctxt)) )
-            goto done;
-        if ( (old_lo != _regs.eax) || (old_hi != _regs.edx) )
-        {
-            _regs.eax = old_lo;
-            _regs.edx = old_hi;
-            _regs.eflags &= ~EFLG_ZF;
-        }
-        else if ( ops->cmpxchg8b == NULL )
-        {
-            rc = X86EMUL_UNHANDLEABLE;
-            goto done;
-        }
-        else
+#ifdef __x86_64__
+        if ( op_bytes != 8 )
         {
-            if ( (rc = ops->cmpxchg8b(ea.mem.seg, ea.mem.off, old_lo, old_hi,
-                                      _regs.ebx, _regs.ecx, ctxt)) != 0 )
+            unsigned long old, new;
+
+            if ( (rc = ops->read(ea.mem.seg, ea.mem.off, &old, 8, ctxt)) != 0 )
                 goto done;
-            _regs.eflags |= EFLG_ZF;
-        }
-        break;
-    }
-#elif defined(__x86_64__)
-    {
-        unsigned long old, new;
-        generate_exception_if((modrm_reg & 7) != 1, EXC_UD, -1);
-        generate_exception_if(ea.type != OP_MEM, EXC_UD, -1);
-        if ( (rc = ops->read(ea.mem.seg, ea.mem.off, &old, 8, ctxt)) != 0 )
-            goto done;
-        if ( ((uint32_t)(old>>0) != (uint32_t)_regs.eax) ||
-             ((uint32_t)(old>>32) != (uint32_t)_regs.edx) )
-        {
-            _regs.eax = (uint32_t)(old>>0);
-            _regs.edx = (uint32_t)(old>>32);
-            _regs.eflags &= ~EFLG_ZF;
+            if ( ((uint32_t)(old>>0) != (uint32_t)_regs.eax) ||
+                 ((uint32_t)(old>>32) != (uint32_t)_regs.edx) )
+            {
+                _regs.eax = (uint32_t)(old>>0);
+                _regs.edx = (uint32_t)(old>>32);
+                _regs.eflags &= ~EFLG_ZF;
+            }
+            else
+            {
+                new = (_regs.ecx<<32)|(uint32_t)_regs.ebx;
+                if ( (rc = ops->cmpxchg(ea.mem.seg, ea.mem.off, old,
+                                        new, 8, ctxt)) != 0 )
+                    goto done;
+                _regs.eflags |= EFLG_ZF;
+            }
         }
+        else if ( !cpu_has_cmpxchg16b )
+            generate_exception_if(1, EXC_UD, -1);
         else
+#endif
         {
-            new = (_regs.ecx<<32)|(uint32_t)_regs.ebx;
-            if ( (rc = ops->cmpxchg(ea.mem.seg, ea.mem.off, old,
-                                    new, 8, ctxt)) != 0 )
+            unsigned long old_lo, old_hi;
+
+            if ( (rc = ops->read(ea.mem.seg, ea.mem.off,
+                                 &old_lo, sizeof(old_lo), ctxt)) ||
+                 (rc = ops->read(ea.mem.seg, ea.mem.off+sizeof(old_lo),
+                                 &old_hi, sizeof(old_lo), ctxt)) )
+                goto done;
+            if ( (old_lo != _regs.eax) || (old_hi != _regs.edx) )
+            {
+                _regs.eax = old_lo;
+                _regs.edx = old_hi;
+                _regs.eflags &= ~EFLG_ZF;
+            }
+            else if ( ops->cmpxchg2 == NULL )
+            {
+                rc = X86EMUL_UNHANDLEABLE;
                 goto done;
-            _regs.eflags |= EFLG_ZF;
+            }
+            else
+            {
+                if ( (rc = ops->cmpxchg2(ea.mem.seg, ea.mem.off, old_lo, 
old_hi,
+                                         _regs.ebx, _regs.ecx, ctxt)) != 0 )
+                    goto done;
+                _regs.eflags |= EFLG_ZF;
+            }
         }
         break;
-    }
-#endif
 
     case 0xc8 ... 0xcf: /* bswap */
         dst.type = OP_REG;
@@ -3409,7 +3413,7 @@ x86_emulate(
         {
         default: /* case 2: */
             /* Undefined behaviour. Writes zero on all tested CPUs. */
-            dst.val = 0;
+            __asm__("data16 bswap %k0" : "+r" (dst.val));
             break;
         case 4:
 #ifdef __x86_64__
Index: 2008-04-15/xen/arch/x86/x86_emulate/x86_emulate.h
===================================================================
--- 2008-04-15.orig/xen/arch/x86/x86_emulate/x86_emulate.h      2008-04-01 
11:10:21.000000000 +0200
+++ 2008-04-15/xen/arch/x86/x86_emulate/x86_emulate.h   2008-04-15 
08:48:15.000000000 +0200
@@ -104,8 +104,9 @@ struct segment_register {
  *     some out-of-band mechanism, unknown to the emulator. The memop signals
  *     failure by returning X86EMUL_EXCEPTION to the emulator, which will
  *     then immediately bail.
- *  2. Valid access sizes are 1, 2, 4 and 8 bytes. On x86/32 systems only
- *     cmpxchg8b_emulated need support 8-byte accesses.
+ *  2. Valid access sizes are 1, 2, 4, 8, and 16 bytes. On x86/32 systems only
+ *     cmpxchg2_emulated need support 8-byte accesses. On x86/64 systems only
+ *     cmpxchg2_emulated need support 16-byte accesses.
  *  3. The emulator cannot handle 64-bit mode emulation on an x86/32 system.
  */
 struct x86_emulate_ops
@@ -165,16 +166,17 @@ struct x86_emulate_ops
         struct x86_emulate_ctxt *ctxt);
 
     /*
-     * cmpxchg8b: Emulate an atomic (LOCKed) CMPXCHG8B operation.
+     * cmpxchg2: Emulate an atomic (LOCKed) CMPXCHG{8,16}B operation.
      *  @old:   [IN ] Value expected to be current at @addr.
      *  @new:   [IN ] Value to write to @addr.
      * NOTES:
-     *  1. This function is only ever called when emulating a real CMPXCHG8B.
-     *  2. This function is *never* called on x86/64 systems.
-     *  2. Not defining this function (i.e., specifying NULL) is equivalent
+     *  1. This function is only ever called when emulating a real 
CMPXCHG{8,16}B.
+     *  2. This function is *never* called on x86/64 systems for emulating
+     *     CMPXCHG8B.
+     *  3. Not defining this function (i.e., specifying NULL) is equivalent
      *     to defining a function that always returns X86EMUL_UNHANDLEABLE.
      */
-    int (*cmpxchg8b)(
+    int (*cmpxchg2)(
         enum x86_segment seg,
         unsigned long offset,
         unsigned long old_lo,
Index: 2008-04-15/xen/arch/x86/x86_emulate.c
===================================================================
--- 2008-04-15.orig/xen/arch/x86/x86_emulate.c  2008-04-01 14:20:52.000000000 
+0200
+++ 2008-04-15/xen/arch/x86/x86_emulate.c       2008-04-15 08:48:15.000000000 
+0200
@@ -12,6 +12,8 @@
 #include <asm/x86_emulate.h>
 
 #undef cmpxchg
+#undef cpuid
+#undef wbinvd
 
 #define __emulate_fpu_insn(_op)                 \
 do{ int _exn;                                   \
Index: 2008-04-15/xen/include/asm-x86/cpufeature.h
===================================================================
--- 2008-04-15.orig/xen/include/asm-x86/cpufeature.h    2008-04-01 
14:20:52.000000000 +0200
+++ 2008-04-15/xen/include/asm-x86/cpufeature.h 2008-04-15 08:48:15.000000000 
+0200
@@ -149,6 +149,7 @@
 #define cpu_has_cyrix_arr      boot_cpu_has(X86_FEATURE_CYRIX_ARR)
 #define cpu_has_centaur_mcr    boot_cpu_has(X86_FEATURE_CENTAUR_MCR)
 #define cpu_has_clflush                boot_cpu_has(X86_FEATURE_CLFLSH)
+#define cpu_has_cmpxchg16b     0
 #define cpu_has_page1gb                0
 #define cpu_has_efer           (boot_cpu_data.x86_capability[1] & 0x20100800)
 #else /* __x86_64__ */
@@ -175,6 +176,7 @@
 #define cpu_has_cyrix_arr      0
 #define cpu_has_centaur_mcr    0
 #define cpu_has_clflush                boot_cpu_has(X86_FEATURE_CLFLSH)
+#define cpu_has_cmpxchg16b     boot_cpu_has(X86_FEATURE_CX16)
 #define cpu_has_page1gb                boot_cpu_has(X86_FEATURE_PAGE1GB)
 #define cpu_has_efer           1
 #endif
Index: 2008-04-15/xen/include/asm-x86/paging.h
===================================================================
--- 2008-04-15.orig/xen/include/asm-x86/paging.h        2008-04-11 
14:48:16.000000000 +0200
+++ 2008-04-15/xen/include/asm-x86/paging.h     2008-04-15 08:48:15.000000000 
+0200
@@ -83,12 +83,14 @@ struct shadow_paging_mode {
                                             unsigned long new,
                                             unsigned int bytes,
                                             struct sh_emulate_ctxt *sh_ctxt);
+#ifdef __i386__
     int           (*x86_emulate_cmpxchg8b )(struct vcpu *v, unsigned long va,
                                             unsigned long old_lo, 
                                             unsigned long old_hi, 
                                             unsigned long new_lo,
                                             unsigned long new_hi,
                                             struct sh_emulate_ctxt *sh_ctxt);
+#endif
     mfn_t         (*make_monitor_table    )(struct vcpu *v);
     void          (*destroy_monitor_table )(struct vcpu *v, mfn_t mmfn);
     int           (*guess_wrmap           )(struct vcpu *v, 
Index: 2008-04-15/xen/include/asm-x86/x86_emulate.h
===================================================================
--- 2008-04-15.orig/xen/include/asm-x86/x86_emulate.h   2008-04-01 
14:20:52.000000000 +0200
+++ 2008-04-15/xen/include/asm-x86/x86_emulate.h        2008-04-15 
08:48:15.000000000 +0200
@@ -16,6 +16,7 @@
 #include <xen/types.h>
 #include <xen/lib.h>
 #include <asm/regs.h>
+#include <asm/processor.h>
 
 #include "../../arch/x86/x86_emulate/x86_emulate.h"
 



_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel


 


Rackspace

Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.