I also have to point out the obvious problem with Xen masquerading as HyperV without implementing the same feature set... KY Srinivasan <kys@xxxxxxxxxxxxx> wrote: > > >> -----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 >> >> -- Sent from my mobile phone. Please excuse brevity and lack of formatting. _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/devel
