On Sun, Feb 03, 2013 at 05:22:38PM -0800, K. Y. Srinivasan wrote: > 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. > > Signed-off-by: K. Y. Srinivasan <k...@microsoft.com>
I'm very curious what's the specific bug that is fixed here? I went over the original discussion in https://patchwork.kernel.org/patch/2064331/ and that's still not clear to me. Is there a configuration that is broken without this patch but starts working with this patch? It seems that one might want to use hyper-v emulation e.g. to test hyper-v code without using windows, so the functionality that this patch disables is not completely useless, so there should be a good reason for disabling it. Could you enlighten me please? :) > --- > arch/x86/kernel/cpu/mshyperv.c | 7 +++++++ > 1 files changed, 7 insertions(+), 0 deletions(-) > > diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c > index 646d192..4dab317 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]); > > -- > 1.7.4.1 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
