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authorK. Y. Srinivasan <kys@microsoft.com>2013-02-03 17:22:38 -0800
committerH. Peter Anvin <hpa@linux.intel.com>2013-02-12 16:27:03 -0800
commitdb34bbb767bdfa1ebed7214b876fe01c5b7ee457 (patch)
tree6cbccf53064b6c56b0a74b551a34e81238008568 /arch/x86/kernel/cpu/mshyperv.c
parent32068f6527b8f1822a30671dedaf59c567325026 (diff)
downloadblackbird-op-linux-db34bbb767bdfa1ebed7214b876fe01c5b7ee457.tar.gz
blackbird-op-linux-db34bbb767bdfa1ebed7214b876fe01c5b7ee457.zip
X86: Add a check to catch Xen emulation of Hyper-V
Xen emulates Hyper-V to host enlightened Windows. Looks like this emulation may be turned on by default even for Linux guests. Check and fail Hyper-V detection if we are on Xen. [ hpa: the problem here is that Xen doesn't emulate Hyper-V well enough, and if the Xen support isn't compiled in, we end up stubling over the Hyper-V emulation and try to activate it -- and it fails. ] Signed-off-by: K. Y. Srinivasan <kys@microsoft.com> Link: http://lkml.kernel.org/r/1359940959-32168-2-git-send-email-kys@microsoft.com Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Diffstat (limited to 'arch/x86/kernel/cpu/mshyperv.c')
-rw-r--r--arch/x86/kernel/cpu/mshyperv.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index 646d192b18a2..4dab317f79b9 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -30,6 +30,13 @@ static bool __init ms_hyperv_platform(void)
if (!boot_cpu_has(X86_FEATURE_HYPERVISOR))
return false;
+ /*
+ * Xen emulates Hyper-V to support enlightened Windows.
+ * Check to see first if we are on a Xen Hypervisor.
+ */
+ if (xen_cpuid_base())
+ return false;
+
cpuid(HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS,
&eax, &hyp_signature[0], &hyp_signature[1], &hyp_signature[2]);
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