[PATCH 0/15] Hypervisor-mode KVM on POWER7 and PPC970

[Alexander Graf]

On 18.06.2011, at 10:27, Paul Mackerras wrote:

> The following series of patches enable KVM to exploit the hardware
> hypervisor mode on 64-bit Power ISA Book3S machines.  At present,
> POWER7 and PPC970 processors are supported.  (Note that the PPC970
> processors in Apple G5 machines don't have a usable hypervisor mode
> and are not supported by these patches.)
> 
> Running the KVM host in hypervisor mode means that the guest can use
> both supervisor mode and user mode.  That means that the guest can
> execute supervisor-privilege instructions and access supervisor-
> privilege registers.  In addition the hardware directs most exceptions
> to the guest.  Thus we don't need to emulate any instructions in the
> host.  Generally, the only times we need to exit the guest are when it
> does a hypercall or when an external interrupt or host timer
> (decrementer) interrupt occurs.
> 
> The focus of this KVM implementation is to run guests that use the
> PAPR (Power Architecture Platform Requirements) paravirtualization
> interface, which is the interface supplied by PowerVM on IBM pSeries
> machines.  Currently the "pseries" machine type in qemu is only
> supported by book3s_hv KVM, and book3s_hv KVM only supports the
> "pseries" machine type.  That will hopefully change in future.
> 
> These patches are against Alex Graf's kvm-ppc-next branch.

Could you please also add some mechanism that sets the guest machine type? We currently support 2:

  * bare metal
  * PAPR

BOOK3S_PR can't do PAPR (yet), BOOK3S_HV can't do bare metal (ever). User space needs to know about these limitations, so it can set the type accordingly and fail to start if kernel space can't provide it.

Since we might end up supporting PAPR even with _pr, it can't just be as simple as a CAP bitmap, since we really need to set the type.


Alex