[Xen-devel] [PATCH v2 1/2] x86/hvm: allow guest to use clflushopt and clwb

[Haozhong Zhang <haozhong.zhang@xxxxxxxxx>]

Pass CPU features CLFLUSHOPT and CLWB into HVM domain so that those two
instructions can be used by guest.

The specification of above two instructions can be found in
https://software.intel.com/sites/default/files/managed/0d/53/319433-022.pdf

Signed-off-by: Haozhong Zhang <haozhong.zhang@xxxxxxxxx>
---
 tools/libxc/xc_cpufeature.h      |  3 ++-
 tools/libxc/xc_cpuid_x86.c       |  4 +++-
 xen/arch/x86/hvm/hvm.c           | 33 +++++++++++++++++++++------------
 xen/include/asm-x86/cpufeature.h |  5 +++++
 4 files changed, 31 insertions(+), 14 deletions(-)

diff --git a/tools/libxc/xc_cpufeature.h b/tools/libxc/xc_cpufeature.h
index c3ddc80..5288ac6 100644
--- a/tools/libxc/xc_cpufeature.h
+++ b/tools/libxc/xc_cpufeature.h
@@ -140,6 +140,7 @@
 #define X86_FEATURE_RDSEED      18 /* RDSEED instruction */
 #define X86_FEATURE_ADX         19 /* ADCX, ADOX instructions */
 #define X86_FEATURE_SMAP        20 /* Supervisor Mode Access Protection */
-
+#define X86_FEATURE_CLFLUSHOPT  23 /* CLFLUSHOPT instruction */
+#define X86_FEATURE_CLWB        24 /* CLWB instruction */
 
 #endif /* __LIBXC_CPUFEATURE_H */
diff --git a/tools/libxc/xc_cpuid_x86.c b/tools/libxc/xc_cpuid_x86.c
index 8882c01..fecfd6c 100644
--- a/tools/libxc/xc_cpuid_x86.c
+++ b/tools/libxc/xc_cpuid_x86.c
@@ -426,7 +426,9 @@ static void xc_cpuid_hvm_policy(xc_interface *xch,
                         bitmaskof(X86_FEATURE_RDSEED)  |
                         bitmaskof(X86_FEATURE_ADX)  |
                         bitmaskof(X86_FEATURE_SMAP) |
-                        bitmaskof(X86_FEATURE_FSGSBASE));
+                        bitmaskof(X86_FEATURE_FSGSBASE) |
+                        bitmaskof(X86_FEATURE_CLWB) |
+                        bitmaskof(X86_FEATURE_CLFLUSHOPT));
         } else
             regs[1] = 0;
         regs[0] = regs[2] = regs[3] = 0;
diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 21470ec..9099188 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -4583,21 +4583,30 @@ void hvm_cpuid(unsigned int input, unsigned int *eax, 
unsigned int *ebx,
             *edx &= ~cpufeat_mask(X86_FEATURE_PSE36);
         break;
     case 0x7:
-        if ( (count == 0) && !cpu_has_smep )
-            *ebx &= ~cpufeat_mask(X86_FEATURE_SMEP);
+        if ( count == 0 )
+        {
+            if ( !cpu_has_smep )
+                *ebx &= ~cpufeat_mask(X86_FEATURE_SMEP);
+
+            if ( !cpu_has_smap )
+                *ebx &= ~cpufeat_mask(X86_FEATURE_SMAP);
+
+            /* Don't expose MPX to hvm when VMX support is not available */
+            if ( !(vmx_vmexit_control & VM_EXIT_CLEAR_BNDCFGS) ||
+                 !(vmx_vmentry_control & VM_ENTRY_LOAD_BNDCFGS) )
+                *ebx &= ~cpufeat_mask(X86_FEATURE_MPX);
 
-        if ( (count == 0) && !cpu_has_smap )
-            *ebx &= ~cpufeat_mask(X86_FEATURE_SMAP);
+            /* Don't expose INVPCID to non-hap hvm. */
+            if ( !hap_enabled(d) )
+                *ebx &= ~cpufeat_mask(X86_FEATURE_INVPCID);
 
-        /* Don't expose MPX to hvm when VMX support is not available */
-        if ( (count == 0) &&
-             (!(vmx_vmexit_control & VM_EXIT_CLEAR_BNDCFGS) ||
-              !(vmx_vmentry_control & VM_ENTRY_LOAD_BNDCFGS)) )
-            *ebx &= ~cpufeat_mask(X86_FEATURE_MPX);
+            if ( !cpu_has_clflushopt )
+                *ebx &= ~cpufeat_mask(X86_FEATURE_CLFLUSHOPT);
+
+            if ( !cpu_has_clwb )
+                *ebx &= ~cpufeat_mask(X86_FEATURE_CLWB);
+        }
 
-        /* Don't expose INVPCID to non-hap hvm. */
-        if ( (count == 0) && !hap_enabled(d) )
-            *ebx &= ~cpufeat_mask(X86_FEATURE_INVPCID);
         break;
     case 0xb:
         /* Fix the x2APIC identifier. */
diff --git a/xen/include/asm-x86/cpufeature.h b/xen/include/asm-x86/cpufeature.h
index ef96514..5818228 100644
--- a/xen/include/asm-x86/cpufeature.h
+++ b/xen/include/asm-x86/cpufeature.h
@@ -162,6 +162,8 @@
 #define X86_FEATURE_RDSEED     (7*32+18) /* RDSEED instruction */
 #define X86_FEATURE_ADX                (7*32+19) /* ADCX, ADOX instructions */
 #define X86_FEATURE_SMAP       (7*32+20) /* Supervisor Mode Access Prevention 
*/
+#define X86_FEATURE_CLFLUSHOPT (7*32+23) /* CLFLUSHOPT instruction */
+#define X86_FEATURE_CLWB       (7*32+24) /* CLWB instruction */
 
 /* Intel-defined CPU features, CPUID level 0x00000007:0 (ecx), word 8 */
 #define X86_FEATURE_PKU        (8*32+ 3) /* Protection Keys for Userspace */
@@ -234,6 +236,9 @@
 #define cpu_has_xgetbv1                boot_cpu_has(X86_FEATURE_XGETBV1)
 #define cpu_has_xsaves         boot_cpu_has(X86_FEATURE_XSAVES)
 
+#define cpu_has_clflushopt  boot_cpu_has(X86_FEATURE_CLFLUSHOPT)
+#define cpu_has_clwb        boot_cpu_has(X86_FEATURE_CLWB)
+
 enum _cache_type {
     CACHE_TYPE_NULL = 0,
     CACHE_TYPE_DATA = 1,
-- 
2.4.8


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