On Thu, Jul 23, 2020 at 03:50:53PM +0530, Ravi Bangoria wrote:
kvm code assumes single DAWR everywhere. Add code to support 2nd DAWR. DAWR is a hypervisor resource and thus H_SET_MODE hcall is used to set/ unset it. Introduce new case H_SET_MODE_RESOURCE_SET_DAWR1 for 2nd DAWR.
Is this the same interface as will be defined in PAPR and available under PowerVM, or is it a new/different interface for KVM?
Also, kvm will support 2nd DAWR only if CPU_FTR_DAWR1 is set.
In general QEMU wants to be able to control all aspects of the virtual machine presented to the guest, meaning that just because a host has a particular hardware capability does not mean we should automatically present that capability to the guest.
In this case, QEMU will want a way to control whether the guest sees the availability of the second DAWR/X registers or not, i.e. whether a H_SET_MODE to set DAWR[X]1 will succeed or fail.