[Xen-changelog] [xen stable-4.8] x86: further CPUID handling adjustments

[patchbot@xxxxxxx]

commit 8f9846f791d2f248651f5fd56724b4c3fabd9d9b
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Wed Apr 18 16:45:56 2018 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Wed Apr 18 16:45:56 2018 +0200

    x86: further CPUID handling adjustments
    
    In particular for Dom0 we need to make sure to surface Spectre related
    feature flags.
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 xen/arch/x86/hvm/hvm.c      | 4 ++++
 xen/arch/x86/traps.c        | 8 ++++++--
 xen/include/asm-x86/cpuid.h | 1 +
 3 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 96afb7b1c2..bc2e676d3d 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -3587,6 +3587,9 @@ void hvm_cpuid(unsigned int input, unsigned int *eax, 
unsigned int *ebx,
 
             *ecx &= hvm_featureset[FEATURESET_7c0];
 
+            *edx |= cpufeat_mask(X86_FEATURE_STIBP);
+            *edx &= hvm_featureset[FEATURESET_7d0];
+
             /* Don't expose HAP-only features to non-hap guests. */
             if ( !hap_enabled(d) )
             {
@@ -3758,6 +3761,7 @@ void hvm_cpuid(unsigned int input, unsigned int *eax, 
unsigned int *ebx,
         hvm_cpuid(0x80000001, NULL, NULL, NULL, &_edx);
         *eax |= (_edx & cpufeat_mask(X86_FEATURE_LM) ? vaddr_bits : 32) << 8;
 
+        *ebx |= cpufeat_mask(X86_FEATURE_IBPB);
         *ebx &= hvm_featureset[FEATURESET_e8b];
         break;
     }
diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c
index 8a3a71dcb4..edb3fa4720 100644
--- a/xen/arch/x86/traps.c
+++ b/xen/arch/x86/traps.c
@@ -1156,6 +1156,9 @@ void pv_cpuid(struct cpu_user_regs *regs)
 
             c &= pv_featureset[FEATURESET_7c0];
 
+            d |= cpufeat_mask(X86_FEATURE_STIBP);
+            d &= pv_featureset[FEATURESET_7d0];
+
             if ( !is_pvh_domain(currd) )
             {
                 /*
@@ -1169,8 +1172,8 @@ void pv_cpuid(struct cpu_user_regs *regs)
             }
         }
         else
-            b = c = 0;
-        a = d = 0;
+            b = c = d = 0;
+        a = 0;
         break;
 
     case XSTATE_CPUID:
@@ -1268,6 +1271,7 @@ void pv_cpuid(struct cpu_user_regs *regs)
 
     case 0x80000008:
         a = paddr_bits | (vaddr_bits << 8);
+        b |= cpufeat_mask(X86_FEATURE_IBPB);
         b &= pv_featureset[FEATURESET_e8b];
         break;
 
diff --git a/xen/include/asm-x86/cpuid.h b/xen/include/asm-x86/cpuid.h
index 2372474791..ec8bbb5378 100644
--- a/xen/include/asm-x86/cpuid.h
+++ b/xen/include/asm-x86/cpuid.h
@@ -17,6 +17,7 @@
 #define FEATURESET_7c0    6 /* 0x00000007:0.ecx    */
 #define FEATURESET_e7d    7 /* 0x80000007.edx      */
 #define FEATURESET_e8b    8 /* 0x80000008.ebx      */
+#define FEATURESET_7d0    9 /* 0x00000007:0.edx    */
 
 #ifndef __ASSEMBLY__
 #include <xen/types.h>
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.8

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