On 02.07.2013, at 00:59, Yoder Stuart-B08248 wrote: > > >> -----Original Message----- >> From: kvm-ppc-owner@xxxxxxxxxxxxxxx [mailto:kvm-ppc-owner@xxxxxxxxxxxxxxx] On Behalf Of Alexander Graf >> Sent: Monday, July 01, 2013 5:14 PM >> To: Yoder Stuart-B08248 >> Cc: Bhushan Bharat-R65777; Wood Scott-B07421; kvm@xxxxxxxxxxxxxxx list; kvm-ppc@xxxxxxxxxxxxxxx >> Subject: Re: RFC: proposal for VM reset & shutdown hcall >> >> >> On 01.07.2013, at 23:59, Yoder Stuart-B08248 wrote: >> >>> For the e500 PV platform we need a VM reset and shutdown mechanisms. >> >> CC'ing kvm-ppc@vger. >> >>> >>> ------------------------------------------------------------------------ >>> Hypercall: KVM_HC_VM_RESET >>> Description: Requests that the virtual machine be reset. The >>> hcall takes no arguments. If successful the hcall does not >>> return. >>> >>> Arguments: >>> r11 hcall-token KVM_HC_VM_RESET >>> >>> Return values >>> r3 status Status of the hcall. If the hcall succeeds >>> it does not return. If an error occurs >>> EV_INTERNAL is returned. >>> ------------------------------------------------------------------------ >>> Hypercall: KVM_HC_VM_SHUTDOWN >>> Description: Requests that the virtual machine be powered-off/halted. >>> The hcall takes no arguments. If successful the hcall does not >>> return. >>> >>> Arguments: >>> r11 hcall-token KVM_HC_VM_SHUTDOWN >>> >>> Return values >>> r3 status Status of the hcall. If the hcall succeeds >>> it does not return. If an error occurs >>> EV_INTERNAL is returned. >>> ------------------------------------------------------------------------ >>> >>> Implementation notes: >>> >>> -expect hcall token to be defined with KVM_HCALL_TOKEN: >>> KVM_HC_VM_RESET >>> KVM_HC_VM_SHUTDOWN >>> >>> -the KVM_HC_FEATURES hcall should be expanded with new feature bits >>> to advertise both new hcalls to the VM: e.g. #define KVM_FEATURE_VM_RESET >> >> Do we really need this? Can't we just leave this up to device tree to tell the guest that this feature >> exists? After all, it's a pure user space matter whether it wants to support reboot & shutdown or not. > > I guess there are two questions I have: > > -does KVM need to advertise to user space that the hcalls exist through > using the KVM_PPC_GET_PVINFO ioctl? IMHO it should only expose a CAP indicating that it forwards unknown hcalls to user space. > -should QEMU advertise this to the guest via a device tree property > or via the KVM_HC_FEATURES hcall. What should KVM_HC_FEATURES be used for? At least today user space doesn't have influence on the KVM_HC_FEATURES hcall. I think that one simply predates the ePAPR way of enumerating hypercall availability through device tree. Alex -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
