>>> On 24.01.13 at 17:07, KY Srinivasan <k...@microsoft.com> wrote:
> >> -----Original Message----- >> From: Jan Beulich [mailto:jbeul...@suse.com] >> Sent: Thursday, January 24, 2013 3:48 AM >> To: KY Srinivasan >> Cc: o...@aepfle.de; b...@alien8.de; a...@canonical.com; x...@kernel.org; >> t...@linutronix.de; de...@linuxdriverproject.org; > gre...@linuxfoundation.org; >> jasow...@redhat.com; linux-kernel@vger.kernel.org; h...@zytor.com >> Subject: Re: [PATCH RESEND 1/1] X86: Handle Hyper-V vmbus interrupts as >> special hypervisor interrupts >> >> >>> On 24.01.13 at 02:17, "K. Y. Srinivasan" <k...@microsoft.com> wrote: >> > @@ -69,6 +74,11 @@ static void __init ms_hyperv_init_platform(void) >> > ms_hyperv.features, ms_hyperv.hints); >> > >> > clocksource_register_hz(&hyperv_cs, NSEC_PER_SEC/100); >> > + >> > + /* >> > + * Setup the IDT for hypervisor callback. >> > + */ >> > + alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR, >> hyperv_callback_vector); >> >> Isn't doing this unconditionally here as problematic as the call to >> clocksource_register_hz() turned out to be when Xen's Hyper-V >> shim reacts to the CPUID inquiry above? > > I was not sure what to make this conditional on at run-time. To the extent > that Xen emulation of Hyper-V is complete, this will be a problem. Does Xen > return all the "feature bits" of Hyper-V. I could discriminate on a feature > that > Xen does not plan to emulate. I've no idea what plans there might be, but that's the code there is currently: int cpuid_viridian_leaves(unsigned int leaf, unsigned int *eax, unsigned int *ebx, unsigned int *ecx, unsigned int *edx) { struct domain *d = current->domain; if ( !is_viridian_domain(d) ) return 0; leaf -= 0x40000000; if ( leaf > 6 ) return 0; *eax = *ebx = *ecx = *edx = 0; switch ( leaf ) { case 0: *eax = 0x40000006; /* Maximum leaf */ *ebx = 0x7263694d; /* Magic numbers */ *ecx = 0x666F736F; *edx = 0x76482074; break; case 1: *eax = 0x31237648; /* Version number */ break; case 2: /* Hypervisor information, but only if the guest has set its own version number. */ if ( d->arch.hvm_domain.viridian.guest_os_id.raw == 0 ) break; *eax = 1; /* Build number */ *ebx = (xen_major_version() << 16) | xen_minor_version(); *ecx = 0; /* SP */ *edx = 0; /* Service branch and number */ break; case 3: /* Which hypervisor MSRs are available to the guest */ *eax = (CPUID3A_MSR_APIC_ACCESS | CPUID3A_MSR_HYPERCALL | CPUID3A_MSR_VP_INDEX); break; case 4: /* Recommended hypercall usage. */ if ( (d->arch.hvm_domain.viridian.guest_os_id.raw == 0) || (d->arch.hvm_domain.viridian.guest_os_id.fields.os < 4) ) break; *eax = (CPUID4A_MSR_BASED_APIC | CPUID4A_RELAX_TIMER_INT); *ebx = 2047; /* long spin count */ break; } return 1; } Question is - considering you stated that this is supported starting in Win8, doesn't Hyper-V itself announce that capability in some explicit way? Jan -- 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/
