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Commit db34bbb767bdfa1ebed7214b876fe01c5b7ee457

Authored by K. Y. Srinivasan
Committed by H. Peter Anvin
1 parent 32068f6527
Exists in smarc-l5.0.0_1.0.0-ga and in 5 other branches imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga

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>

Showing 1 changed file with 7 additions and 0 deletions Side-by-side Diff

arch/x86/kernel/cpu/mshyperv.c
Diff comments   View file @ db34bbb
... ... @@ -30,6 +30,13 @@
30 30 if (!boot_cpu_has(X86_FEATURE_HYPERVISOR))
31 31 return false;
32 32  
  33 + /*
  34 + * Xen emulates Hyper-V to support enlightened Windows.
  35 + * Check to see first if we are on a Xen Hypervisor.
  36 + */
  37 + if (xen_cpuid_base())
  38 + return false;
  39 +
33 40 cpuid(HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS,
34 41 &eax, &hyp_signature[0], &hyp_signature[1], &hyp_signature[2]);
35 42