[Xen-devel] [PATCH 2/6] x86emul: support WBNOINVD

[Jan Beulich <JBeulich@suse.com>]

Rev 035 of Intel's ISA extensions document does not state intercept
behavior for the insn (I've been in-officially told that the distinction
is going to be by exit qualification, as I would have assumed
considering that this way it's sufficiently transparent to unaware
software, and using WBINVD in place of WBNOINVD is always correct, just
less efficient), so in the HVM case for now it'll be backed by the same
->wbinvd_intercept() handlers.

Use this occasion and also add the two missing table entries for
CLDEMOTE, which doesn't require any further changes to make work.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
---
v2: Re-base. Convert wbnoinvd() inline function.

--- a/tools/libxl/libxl_cpuid.c
+++ b/tools/libxl/libxl_cpuid.c
@@ -208,6 +208,7 @@ int libxl_cpuid_parse_config(libxl_cpuid
          {"avx512-bitalg",0x00000007,  0, CPUID_REG_ECX, 12,  1},
          {"avx512-vpopcntdq",0x00000007,0,CPUID_REG_ECX, 14,  1},
          {"rdpid",        0x00000007,  0, CPUID_REG_ECX, 22,  1},
+        {"cldemote",     0x00000007,  0, CPUID_REG_ECX, 25,  1},
  
          {"avx512-4vnniw",0x00000007,  0, CPUID_REG_EDX,  2,  1},
          {"avx512-4fmaps",0x00000007,  0, CPUID_REG_EDX,  3,  1},
@@ -256,6 +257,7 @@ int libxl_cpuid_parse_config(libxl_cpuid
  
          {"invtsc",       0x80000007, NA, CPUID_REG_EDX,  8,  1},
  
+        {"wbnoinvd",     0x80000008, NA, CPUID_REG_EBX,  9,  1},
          {"ibpb",         0x80000008, NA, CPUID_REG_EBX, 12,  1},
          {"nc",           0x80000008, NA, CPUID_REG_ECX,  0,  8},
          {"apicidsize",   0x80000008, NA, CPUID_REG_ECX, 12,  4},
--- a/tools/misc/xen-cpuid.c
+++ b/tools/misc/xen-cpuid.c
@@ -146,6 +146,8 @@ static const char *const str_e8b[32] =
  {
      [ 0] = "clzero",
  
+    /* [ 8] */            [ 9] = "wbnoinvd",
+
      [12] = "ibpb",
  };
  
--- a/xen/arch/x86/hvm/emulate.c
+++ b/xen/arch/x86/hvm/emulate.c
@@ -2202,6 +2202,7 @@ static int hvmemul_cache_op(
          /* fall through */
      case x86emul_invd:
      case x86emul_wbinvd:
+    case x86emul_wbnoinvd:
          alternative_vcall(hvm_funcs.wbinvd_intercept);
          break;
      }
--- a/xen/arch/x86/pv/emul-priv-op.c
+++ b/xen/arch/x86/pv/emul-priv-op.c
@@ -1121,7 +1121,7 @@ static int write_msr(unsigned int reg, u
  static int cache_op(enum x86emul_cache_op op, enum x86_segment seg,
                      unsigned long offset, struct x86_emulate_ctxt *ctxt)
  {
-    ASSERT(op == x86emul_wbinvd);
+    ASSERT(op == x86emul_wbinvd || op == x86emul_wbnoinvd);
  
      /* Ignore the instruction if unprivileged. */
      if ( !cache_flush_permitted(current->domain) )
@@ -1130,6 +1130,8 @@ static int cache_op(enum x86emul_cache_o
           * newer linux uses this in some start-of-day timing loops.
           */
          ;
+    else if ( op == x86emul_wbnoinvd && cpu_has_wbnoinvd )
+        wbnoinvd();
      else
          wbinvd();
  
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -1869,6 +1869,7 @@ in_protmode(
  #define vcpu_has_fma4()        (ctxt->cpuid->extd.fma4)
  #define vcpu_has_tbm()         (ctxt->cpuid->extd.tbm)
  #define vcpu_has_clzero()      (ctxt->cpuid->extd.clzero)
+#define vcpu_has_wbnoinvd()    (ctxt->cpuid->extd.wbnoinvd)
  
  #define vcpu_has_bmi1()        (ctxt->cpuid->feat.bmi1)
  #define vcpu_has_hle()         (ctxt->cpuid->feat.hle)
@@ -5931,10 +5932,13 @@ x86_emulate(
          break;
  
      case X86EMUL_OPC(0x0f, 0x08): /* invd */
-    case X86EMUL_OPC(0x0f, 0x09): /* wbinvd */
+    case X86EMUL_OPC(0x0f, 0x09): /* wbinvd / wbnoinvd */
          generate_exception_if(!mode_ring0(), EXC_GP, 0);
          fail_if(!ops->cache_op);
-        if ( (rc = ops->cache_op(b == 0x09 ? x86emul_wbinvd
+        if ( (rc = ops->cache_op(b == 0x09 ? !repe_prefix() ||
+                                             !vcpu_has_wbnoinvd()
+                                             ? x86emul_wbinvd
+                                             : x86emul_wbnoinvd
                                             : x86emul_invd,
                                   x86_seg_none, 0,
                                   ctxt)) != X86EMUL_OKAY )
--- a/xen/arch/x86/x86_emulate/x86_emulate.h
+++ b/xen/arch/x86/x86_emulate/x86_emulate.h
@@ -182,6 +182,7 @@ enum x86emul_cache_op {
      x86emul_clwb,
      x86emul_invd,
      x86emul_wbinvd,
+    x86emul_wbnoinvd,
  };
  
  struct x86_emulate_state;
--- a/xen/include/asm-x86/cpufeature.h
+++ b/xen/include/asm-x86/cpufeature.h
@@ -129,6 +129,9 @@
  #define cpu_has_avx512_4fmaps   boot_cpu_has(X86_FEATURE_AVX512_4FMAPS)
  #define cpu_has_tsx_force_abort boot_cpu_has(X86_FEATURE_TSX_FORCE_ABORT)
  
+/* CPUID level 0x80000008.ebx */
+#define cpu_has_wbnoinvd        boot_cpu_has(X86_FEATURE_WBNOINVD)
+
  /* Synthesized. */
  #define cpu_has_arch_perfmon    boot_cpu_has(X86_FEATURE_ARCH_PERFMON)
  #define cpu_has_cpuid_faulting  boot_cpu_has(X86_FEATURE_CPUID_FAULTING)
--- a/xen/include/asm-x86/system.h
+++ b/xen/include/asm-x86/system.h
@@ -16,6 +16,11 @@ static inline void wbinvd(void)
      asm volatile ( "wbinvd" ::: "memory" );
  }
  
+static inline void wbnoinvd(void)
+{
+    asm volatile ( "repe; wbinvd" : : : "memory" );
+}
+
  static inline void clflush(const void *p)
  {
      asm volatile ( "clflush %0" :: "m" (*(const char *)p) );
--- a/xen/include/public/arch-x86/cpufeatureset.h
+++ b/xen/include/public/arch-x86/cpufeatureset.h
@@ -236,6 +236,7 @@ XEN_CPUFEATURE(AVX512_VNNI,   6*32+11) /
  XEN_CPUFEATURE(AVX512_BITALG, 6*32+12) /*A  Support for VPOPCNT[B,W] and VPSHUFBITQMB */
  XEN_CPUFEATURE(AVX512_VPOPCNTDQ, 6*32+14) /*A  POPCNT for vectors of DW/QW */
  XEN_CPUFEATURE(RDPID,         6*32+22) /*A  RDPID instruction */
+XEN_CPUFEATURE(CLDEMOTE,      6*32+25) /*A  CLDEMOTE instruction */
  
  /* AMD-defined CPU features, CPUID level 0x80000007.edx, word 7 */
  XEN_CPUFEATURE(ITSC,          7*32+ 8) /*   Invariant TSC */
@@ -243,6 +244,7 @@ XEN_CPUFEATURE(EFRO,          7*32+10) /
  
  /* AMD-defined CPU features, CPUID level 0x80000008.ebx, word 8 */
  XEN_CPUFEATURE(CLZERO,        8*32+ 0) /*A  CLZERO instruction */
+XEN_CPUFEATURE(WBNOINVD,      8*32+ 9) /*A  WBNOINVD instruction */
  XEN_CPUFEATURE(IBPB,          8*32+12) /*A  IBPB support only (no IBRS, used by AMD) */
  
  /* Intel-defined CPU features, CPUID level 0x00000007:0.edx, word 9 */

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