[Xen-changelog] [xen master] x86: correct remaining extended CPUID level checks

[patchbot@xxxxxxx]

commit a6abcd8f758d968f6eb4d93ab37db4388eb9df7e
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Wed May 11 09:47:21 2016 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Wed May 11 09:47:21 2016 +0200

    x86: correct remaining extended CPUID level checks
    
    We should consistently check the upper 16 bits to be equal 0x8000 and
    only then the full value to be >= the desired level.
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Release-acked-by: Wei Liu <wei.liu2@xxxxxxxxxx>
---
 xen/arch/x86/boot/head.S    | 3 +++
 xen/arch/x86/cpu/common.c   | 9 ++++++---
 xen/arch/x86/efi/efi-boot.h | 4 +++-
 xen/arch/x86/hvm/hvm.c      | 2 +-
 xen/arch/x86/hvm/mtrr.c     | 2 +-
 5 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/xen/arch/x86/boot/head.S b/xen/arch/x86/boot/head.S
index f3501fd..0999997 100644
--- a/xen/arch/x86/boot/head.S
+++ b/xen/arch/x86/boot/head.S
@@ -133,7 +133,10 @@ __start:
         /* Interrogate CPU extended features via CPUID. */
         mov     $0x80000000,%eax
         cpuid
+        shld    $16,%eax,%ecx
         xor     %edx,%edx
+        cmp     $0x8000,%cx         # any function @ 0x8000xxxx?
+        jne     1f
         cmp     $0x80000000,%eax    # any function > 0x80000000?
         jbe     1f
         mov     $0x80000001,%eax
diff --git a/xen/arch/x86/cpu/common.c b/xen/arch/x86/cpu/common.c
index 4b56061..760543b 100644
--- a/xen/arch/x86/cpu/common.c
+++ b/xen/arch/x86/cpu/common.c
@@ -297,9 +297,12 @@ static void generic_identify(struct cpuinfo_x86 *c)
 
        /* AMD-defined flags: level 0x80000001 */
        c->extended_cpuid_level = cpuid_eax(0x80000000);
-       cpuid(0x80000001, &tmp, &tmp,
-             &c->x86_capability[cpufeat_word(X86_FEATURE_LAHF_LM)],
-             &c->x86_capability[cpufeat_word(X86_FEATURE_SYSCALL)]);
+       if ((c->extended_cpuid_level >> 16) != 0x8000)
+               c->extended_cpuid_level = 0;
+       if (c->extended_cpuid_level > 0x80000000)
+               cpuid(0x80000001, &tmp, &tmp,
+                     &c->x86_capability[cpufeat_word(X86_FEATURE_LAHF_LM)],
+                     &c->x86_capability[cpufeat_word(X86_FEATURE_SYSCALL)]);
        if (c == &boot_cpu_data)
                bootsym(cpuid_ext_features) =
                        c->x86_capability[cpufeat_word(X86_FEATURE_NX)];
diff --git a/xen/arch/x86/efi/efi-boot.h b/xen/arch/x86/efi/efi-boot.h
index 6dbb14d..1fa9e47 100644
--- a/xen/arch/x86/efi/efi-boot.h
+++ b/xen/arch/x86/efi/efi-boot.h
@@ -605,7 +605,9 @@ static void __init efi_arch_handle_module(struct file 
*file, const CHAR16 *name,
 
 static void __init efi_arch_cpu(void)
 {
-    if ( cpuid_eax(0x80000000) > 0x80000000 )
+    uint32_t eax = cpuid_eax(0x80000000);
+
+    if ( (eax >> 16) == 0x8000 && eax > 0x80000000 )
     {
         cpuid_ext_features = cpuid_edx(0x80000001);
         boot_cpu_data.x86_capability[cpufeat_word(X86_FEATURE_SYSCALL)]
diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 917db56..7492030 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -884,7 +884,7 @@ const char *hvm_efer_valid(const struct vcpu *v, uint64_t 
value,
 
         ASSERT(v->domain == current->domain);
         hvm_cpuid(0x80000000, &level, NULL, NULL, NULL);
-        if ( level >= 0x80000001 )
+        if ( (level >> 16) == 0x8000 && level > 0x80000000 )
         {
             unsigned int dummy;
 
diff --git a/xen/arch/x86/hvm/mtrr.c b/xen/arch/x86/hvm/mtrr.c
index 7ab7f63..f7831ff 100644
--- a/xen/arch/x86/hvm/mtrr.c
+++ b/xen/arch/x86/hvm/mtrr.c
@@ -455,7 +455,7 @@ bool_t mtrr_var_range_msr_set(
     {
         phys_addr = 36;
         hvm_cpuid(0x80000000, &eax, NULL, NULL, NULL);
-        if ( eax >= 0x80000008 )
+        if ( (eax >> 16) == 0x8000 && eax >= 0x80000008 )
         {
             hvm_cpuid(0x80000008, &eax, NULL, NULL, NULL);
             phys_addr = (uint8_t)eax;
--
generated by git-patchbot for /home/xen/git/xen.git#master

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