Re: [PATCH v5 18/18] kvm: arm64: Allow tuning the physical address size for VM

[Suzuki K Poulose]

On 09/25/2018 11:00 AM, Auger Eric wrote:
> Hi Suzuki,
> On 9/17/18 12:41 PM, Suzuki K Poulose wrote:
> > Allow specifying the physical address size limit for a new
> > VM via the kvm_type argument for the KVM_CREATE_VM ioctl. This
> > allows us to finalise the stage2 page table as early as possible
> > and hence perform the right checks on the memory slots
> > without complication. The size is ecnoded as Log2(PA_Size) in
> encoded

...

> > diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
> > index c664064f76fb..f860251ff27c 100644
> > --- a/Documentation/virtual/kvm/api.txt
> > +++ b/Documentation/virtual/kvm/api.txt
> > @@ -122,6 +122,14 @@ the default trap & emulate implementation (which changes the virtual
> >   memory layout to fit in user mode), check KVM_CAP_MIPS_VZ and use the
> >   flag KVM_VM_MIPS_VZ.
> >   
> > +To configure the physical address space size for a VM (IPA size) on arm64,
> > +check KVM_CAP_ARM_VM_PHYS_SHIFT (which returns the maximum limit for the
> > +IPA shift) and use KVM_VM_TYPE_ARM_PHYS_SHIFT(PHYS_SHIFT). Bits[7-0] of the
> > +machine type has been reserved for specifying the PHYS_SHIFT.
> are reserved to pass the PHYS_SHIFT?
> > +The supported range is [32...IPA_LIMIT], where IPA_LIMIT could be
> s/could be/is



> > diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> > index 07548de5c988..2a6b29c446db 100644
> > --- a/include/uapi/linux/kvm.h
> > +++ b/include/uapi/linux/kvm.h
> > @@ -750,6 +750,15 @@ struct kvm_ppc_resize_hpt {
> >   
> >   #define KVM_S390_SIE_PAGE_OFFSET 1
> >   
> > +/*
> > + * On arm64, machine type can be used to request the physical
> > + * address size for the VM. Bits[7-0] has been reserved for the PA
> s/has been reserved/are?

Thanks for spotting, fixed all the above.

Suzuki