[Xen-changelog] [xen stable-4.3] x86/HVM: correct the SMEP logic for HVM_CR0_GUEST_RESERVED_BITS

[patchbot@xxxxxxx]

commit 8da3f25d0564886709e58ad1d44971f0b833fe5b
Author:     Feng Wu <feng.wu@xxxxxxxxx>
AuthorDate: Mon May 12 17:26:06 2014 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Mon May 12 17:26:06 2014 +0200

    x86/HVM: correct the SMEP logic for HVM_CR0_GUEST_RESERVED_BITS
    
    When checking the SMEP feature for HVM guests, we should check the
    VCPU instead of the host CPU.
    
    Signed-off-by: Feng Wu <feng.wu@xxxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    master commit: 31ee951a3bee6e7cc21f94f900fe989e3701a79a
    master date: 2014-04-28 12:47:24 +0200
---
 xen/include/asm-x86/hvm/hvm.h |   15 ++++++++++++++-
 1 files changed, 14 insertions(+), 1 deletions(-)

diff --git a/xen/include/asm-x86/hvm/hvm.h b/xen/include/asm-x86/hvm/hvm.h
index 144ba6a..2cd2f8c 100644
--- a/xen/include/asm-x86/hvm/hvm.h
+++ b/xen/include/asm-x86/hvm/hvm.h
@@ -343,6 +343,19 @@ static inline int hvm_event_pending(struct vcpu *v)
     return hvm_funcs.event_pending(v);
 }
 
+static inline bool_t hvm_vcpu_has_smep(void)
+{
+    unsigned int eax, ebx, ecx = 0, dummy;
+
+    hvm_cpuid(0, &eax, &dummy, &dummy, &dummy);
+
+    if ( eax < 7 )
+        return 0;
+
+    hvm_cpuid(7, &dummy, &ebx, &ecx, &dummy);
+    return !!(ebx & cpufeat_mask(X86_FEATURE_SMEP));
+}
+
 /* These reserved bits in lower 32 remain 0 after any load of CR0 */
 #define HVM_CR0_GUEST_RESERVED_BITS             \
     (~((unsigned long)                          \
@@ -362,7 +375,7 @@ static inline int hvm_event_pending(struct vcpu *v)
         X86_CR4_DE  | X86_CR4_PSE | X86_CR4_PAE |       \
         X86_CR4_MCE | X86_CR4_PGE | X86_CR4_PCE |       \
         X86_CR4_OSFXSR | X86_CR4_OSXMMEXCPT |           \
-        (cpu_has_smep ? X86_CR4_SMEP : 0) |             \
+        (hvm_vcpu_has_smep() ? X86_CR4_SMEP : 0) |      \
         (cpu_has_fsgsbase ? X86_CR4_FSGSBASE : 0) |     \
         ((nestedhvm_enabled((_v)->domain) && cpu_has_vmx)\
                       ? X86_CR4_VMXE : 0)  |             \
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.3

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