Messages in this thread | | | Date | Wed, 2 Sep 2020 12:01:24 +1000 | From | Paul Mackerras <> | Subject | Re: [PATCH 2/7] powerpc/watchpoint/kvm: Add infrastructure to support 2nd DAWR |
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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.
Paul.
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