On Mon, Jul 15, 2013 at 02:26:38PM +0200, Alexander Graf wrote:
>
> On 15.07.2013, at 14:24, Gleb Natapov wrote:
>
> > On Mon, Jul 15, 2013 at 02:21:51PM +0200, Alexander Graf wrote:
> >>
> >> On 15.07.2013, at 14:15, Gleb Natapov wrote:
> >>
> >>> On Mon, Jul 15, 2013 at 01:44:46PM +0200, Alexander Graf wrote:
> >>>>
> >>>> On 15.07.2013, at 13:30, Gleb Natapov wrote:
> >>>>
> >>>>> On Mon, Jul 15, 2013 at 04:41:17PM +0530, Bharat Bhushan wrote:
> >>>>>> KVM_HC_VM_RESET: Requests that the virtual machine be reset.
> >>>>>> KVM_HC_VM_SHUTDOWN: Requests that the virtual machine be
> >>>>>> powered-off/halted.
> >>>>>>
> >>>>>> These hcalls are handled by guest userspace.
> >>>>>>
> >>>>>> Signed-off-by: Bharat Bhushan <bharat.bhus...@freescale.com>
> >>>>>> ---
> >>>>>> Documentation/virtual/kvm/hypercalls.txt | 16 ++++++++++++++++
> >>>>>> include/uapi/linux/kvm_para.h | 3 ++-
> >>>>>> 2 files changed, 18 insertions(+), 1 deletions(-)
> >>>>>>
> >>>>>> diff --git a/Documentation/virtual/kvm/hypercalls.txt
> >>>>>> b/Documentation/virtual/kvm/hypercalls.txt
> >>>>>> index ea113b5..58acdc1 100644
> >>>>>> --- a/Documentation/virtual/kvm/hypercalls.txt
> >>>>>> +++ b/Documentation/virtual/kvm/hypercalls.txt
> >>>>>> @@ -64,3 +64,19 @@ Purpose: To enable communication between the
> >>>>>> hypervisor and guest there is a
> >>>>>> shared page that contains parts of supervisor visible register state.
> >>>>>> The guest can map this shared page to access its supervisor register
> >>>>>> through
> >>>>>> memory using this hypercall.
> >>>>>> +
> >>>>>> +5. KVM_HC_VM_RESET
> >>>>>> +------------------------
> >>>>>> +Architecture: PPC
> >>>>>> +Status: active
> >>>>>> +Purpose: Requests that the virtual machine be reset. The hcall
> >>>>>> takes no
> >>>>>> +arguments. If successful the hcall does not return. If an error
> >>>>>> occurs it
> >>>>>> +returns EV_INTERNAL.
> >>>>>> +
> >>>>>> +6. KVM_HC_VM_SHUTDOWN
> >>>>>> +------------------------
> >>>>>> +Architecture: PPC
> >>>>>> +Status: active
> >>>>>> +Purpose: Requests that the virtual machine be powered-off/halted.
> >>>>>> +The hcall takes no arguments. If successful the hcall does not return.
> >>>>>> +If an error occurs it returns EV_INTERNAL.
> >>>>>> diff --git a/include/uapi/linux/kvm_para.h
> >>>>>> b/include/uapi/linux/kvm_para.h
> >>>>>> index cea2c5c..218882d 100644
> >>>>>> --- a/include/uapi/linux/kvm_para.h
> >>>>>> +++ b/include/uapi/linux/kvm_para.h
> >>>>>> @@ -19,7 +19,8 @@
> >>>>>> #define KVM_HC_MMU_OP 2
> >>>>>> #define KVM_HC_FEATURES 3
> >>>>>> #define KVM_HC_PPC_MAP_MAGIC_PAGE 4
> >>>>>> -
> >>>>>> +#define KVM_HC_VM_RESET 5
> >>>>>> +#define KVM_HC_VM_SHUTDOWN 6
> >>>>> There is no much sense to share hypercalls between architectures. There
> >>>>> is zero probability x86 will implement those for instance (not sure
> >>>>> why PPC will want them either instead of emulating devices that do
> >>>>> shutdown/reset
> >>>>
> >>>> Implementing devices gets pretty tricky. Usually all of your devices sit
> >>>> on the SoC with a strictly defined layout. We can randomly shove some
> >>>> device in there, but there's a good chance we're overlapping with
> >>>> another device.
> >>>>
> >>> I thought we have device trees to sort these things out.
> >>
> >> For Linux guests, yes :). For proprietary random other guests, no.
> >>
> > But those can't use hcalls too, no?
>
> Why not? There are customers out there who are more than happy to add
> functionality, but not change functionality.
>
Ah, so you are talking about proprietary guests that are actively
developed and it is easier to use separate address space than make them
parse device tree or agree upon common device location, oh well.
--
Gleb.
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