Displaying 9 results from an estimated 9 matches for "davidhep".
2014 Sep 18
3
Standardizing an MSR or other hypercall to get an RNG seed?
I'm not sure what you mean by "this mechanism?" Are you suggesting that each hypervisor put "CrossHVPara\0" somewhere in the 0x40000000 - 0x400fffff CPUID range, and an OS has to do a full scan of this CPUID range on boot to find it? That seems pretty inefficient. An OS will take 1000's of hypervisor intercepts on every boot just to search this CPUID range.
I
2014 Sep 18
3
Standardizing an MSR or other hypercall to get an RNG seed?
I'm not sure what you mean by "this mechanism?" Are you suggesting that each hypervisor put "CrossHVPara\0" somewhere in the 0x40000000 - 0x400fffff CPUID range, and an OS has to do a full scan of this CPUID range on boot to find it? That seems pretty inefficient. An OS will take 1000's of hypervisor intercepts on every boot just to search this CPUID range.
I
2014 Sep 18
0
Standardizing an MSR or other hypercall to get an RNG seed?
On Thu, Sep 18, 2014 at 2:46 PM, David Hepkin <davidhep at microsoft.com> wrote:
> I'm not sure what you mean by "this mechanism?" Are you suggesting that each hypervisor put "CrossHVPara\0" somewhere in the 0x40000000 - 0x400fffff CPUID range, and an OS has to do a full scan of this CPUID range on boot to find it? That s...
2014 Sep 19
2
Standardizing an MSR or other hypercall to get an RNG seed?
On Thu, Sep 18, 2014 at 03:00:05PM -0700, Andy Lutomirski wrote:
> On Thu, Sep 18, 2014 at 2:46 PM, David Hepkin <davidhep at microsoft.com> wrote:
> > I suggest we come to consensus on a specific CPUID leaf where an OS needs to look to determine if a hypervisor supports this capability. We could define a new CPUID leaf range at a well-defined location, or we could just use one of the existing CPUID leaf rang...
2014 Sep 19
2
Standardizing an MSR or other hypercall to get an RNG seed?
On Thu, Sep 18, 2014 at 03:00:05PM -0700, Andy Lutomirski wrote:
> On Thu, Sep 18, 2014 at 2:46 PM, David Hepkin <davidhep at microsoft.com> wrote:
> > I suggest we come to consensus on a specific CPUID leaf where an OS needs to look to determine if a hypervisor supports this capability. We could define a new CPUID leaf range at a well-defined location, or we could just use one of the existing CPUID leaf rang...
2014 Sep 18
5
Standardizing an MSR or other hypercall to get an RNG seed?
On Thu, Sep 18, 2014 at 11:58 AM, Paolo Bonzini <pbonzini at redhat.com> wrote:
>
>> > Actually, that MSR address range has been reserved for that purpose, along
>> > with:
>> > - CPUID.EAX=1 -> ECX bit 31 (always returns 0 on bare metal)
>> > - CPUID.EAX=4000_00xxH leaves (i.e. HYPERVISOR CPUID)
>>
>> I don't know whether this is
2014 Sep 18
5
Standardizing an MSR or other hypercall to get an RNG seed?
On Thu, Sep 18, 2014 at 11:58 AM, Paolo Bonzini <pbonzini at redhat.com> wrote:
>
>> > Actually, that MSR address range has been reserved for that purpose, along
>> > with:
>> > - CPUID.EAX=1 -> ECX bit 31 (always returns 0 on bare metal)
>> > - CPUID.EAX=4000_00xxH leaves (i.e. HYPERVISOR CPUID)
>>
>> I don't know whether this is
2014 Sep 18
1
Standardizing an MSR or other hypercall to get an RNG seed?
The chief advantage I see to using a hypercall based mechanism is that it would work across more architectures. MSR's and CPUID's are specific to X86. If we ever wanted this same mechanism to be available on an architecture that doesn't support MSR's, a hypercall based approach would allow for a more consistent mechanism across the architectures.
I agree, though, that
2014 Sep 18
1
Standardizing an MSR or other hypercall to get an RNG seed?
The chief advantage I see to using a hypercall based mechanism is that it would work across more architectures. MSR's and CPUID's are specific to X86. If we ever wanted this same mechanism to be available on an architecture that doesn't support MSR's, a hypercall based approach would allow for a more consistent mechanism across the architectures.
I agree, though, that