On Thu, Apr 18, 2013 at 08:44:46AM -0700, K. Y. Srinivasan wrote:
> Install the Hyper-V specific interrupt handler only when needed. This would
> permit us to get rid of the Xen check. Note that when the vmbus drivers invokes
> the call to register its handler, we are sure to be running on Hyper-V.
>
> Signed-off-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx>
Looks good to me, this will address the concern. FWIW
Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
Any chance we can fast-path this patch into 3.9 so that we don't release
a kernel with hyper-v on Xen completely disabled?
> ---
> arch/x86/kernel/cpu/mshyperv.c | 18 +++++-------------
> 1 files changed, 5 insertions(+), 13 deletions(-)
>
> diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
> index a7d26d8..8f4be53 100644
> --- a/arch/x86/kernel/cpu/mshyperv.c
> +++ b/arch/x86/kernel/cpu/mshyperv.c
> @@ -35,13 +35,6 @@ 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]);
>
> @@ -82,12 +75,6 @@ static void __init ms_hyperv_init_platform(void)
>
> if (ms_hyperv.features & HV_X64_MSR_TIME_REF_COUNT_AVAILABLE)
> clocksource_register_hz(&hyperv_cs, NSEC_PER_SEC/100);
> -#if IS_ENABLED(CONFIG_HYPERV)
> - /*
> - * Setup the IDT for hypervisor callback.
> - */
> - alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR, hyperv_callback_vector);
> -#endif
> }
>
> const __refconst struct hypervisor_x86 x86_hyper_ms_hyperv = {
> @@ -103,6 +90,11 @@ static irq_handler_t vmbus_isr;
>
> void hv_register_vmbus_handler(int irq, irq_handler_t handler)
> {
> + /*
> + * Setup the IDT for hypervisor callback.
> + */
> + alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR, hyperv_callback_vector);
> +
> vmbus_irq = irq;
> vmbus_isr = handler;
> }
> --
> 1.7.4.1
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