> -----Original Message----- > From: Jan Beulich [mailto:JBeulich@xxxxxxxx] > Sent: Thursday, January 24, 2013 11:16 AM > To: KY Srinivasan > Cc: olaf@xxxxxxxxx; bp@xxxxxxxxx; apw@xxxxxxxxxxxxx; x86@xxxxxxxxxx; > tglx@xxxxxxxxxxxxx; devel@xxxxxxxxxxxxxxxxxxxxxx; gregkh@xxxxxxxxxxxxxxxxxxx; > jasowang@xxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; hpa@xxxxxxxxx > Subject: RE: [PATCH RESEND 1/1] X86: Handle Hyper-V vmbus interrupts as > special hypervisor interrupts > > >>> On 24.01.13 at 17:07, KY Srinivasan <kys@xxxxxxxxxxxxx> wrote: > > > > >> -----Original Message----- > >> From: Jan Beulich [mailto:JBeulich@xxxxxxxx] > >> Sent: Thursday, January 24, 2013 3:48 AM > >> To: KY Srinivasan > >> Cc: olaf@xxxxxxxxx; bp@xxxxxxxxx; apw@xxxxxxxxxxxxx; x86@xxxxxxxxxx; > >> tglx@xxxxxxxxxxxxx; devel@xxxxxxxxxxxxxxxxxxxxxx; > > gregkh@xxxxxxxxxxxxxxxxxxx; > >> jasowang@xxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; hpa@xxxxxxxxx > >> 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" <kys@xxxxxxxxxxxxx> 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? Thanks Jan. Unfortunately I don't think tis interrupt delivery model is specified via a "feature" bit (I will check with the Windows guys). Perhaps, we can have a Hyper-V specific compilation switch to address the Xen emulation issue. Regards, K. Y > > Jan > > _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/devel
