Re: [PATCH 5/5] KVM: arm64: Define KVM_PHYS_SHIFT_MIN

[Marc Zyngier]

On 2021-08-10 16:19, Anshuman Khandual wrote:
> On 8/10/21 6:59 PM, Marc Zyngier wrote:
> > On 2021-08-10 08:02, Anshuman Khandual wrote:
> > > Drop the hard coded value for the minimum IPA range i.e 32 bit. 
> > > Instead
> > > define a macro KVM_PHYS_SHIFT_MIN which improves the code 
> > > readability.
> > >
> > > Cc: Marc Zyngier <maz@xxxxxxxxxx>
> > > Cc: James Morse <james.morse@xxxxxxx>
> > > Cc: Alexandru Elisei <alexandru.elisei@xxxxxxx>
> > > Cc: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
> > > Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
> > > Cc: Will Deacon <will@xxxxxxxxxx>
> > > Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> > > Cc: kvmarm@xxxxxxxxxxxxxxxxxxxxx
> > > Cc: linux-kernel@xxxxxxxxxxxxxxx
> > > Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx>
> > > ---
> > >  arch/arm64/include/asm/kvm_mmu.h | 3 ++-
> > >  arch/arm64/kvm/reset.c           | 2 +-
> > >  2 files changed, 3 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/arch/arm64/include/asm/kvm_mmu.h 
> > > b/arch/arm64/include/asm/kvm_mmu.h
> > > index b52c5c4b9a3d..716f999818d9 100644
> > > --- a/arch/arm64/include/asm/kvm_mmu.h
> > > +++ b/arch/arm64/include/asm/kvm_mmu.h
> > > @@ -141,7 +141,8 @@ static __always_inline unsigned long
> > > __kern_hyp_va(unsigned long v)
> > >   * We currently support using a VM-specified IPA size. For backward
> > >   * compatibility, the default IPA size is fixed to 40bits.
> > >   */
> > > -#define KVM_PHYS_SHIFT    (40)
> > > +#define KVM_PHYS_SHIFT        (40)
> > > +#define KVM_PHYS_SHIFT_MIN    (32)
> > >
> > >  #define kvm_phys_shift(kvm)        VTCR_EL2_IPA(kvm->arch.vtcr)
> > >  #define kvm_phys_size(kvm)        (_AC(1, ULL) << 
> > > kvm_phys_shift(kvm))
> > > diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
> > > index cba7872d69a8..8dc8b4b9de37 100644
> > > --- a/arch/arm64/kvm/reset.c
> > > +++ b/arch/arm64/kvm/reset.c
> > > @@ -369,7 +369,7 @@ int kvm_arm_setup_stage2(struct kvm *kvm, 
> > > unsigned
> > > long type)
> > >      phys_shift = KVM_VM_TYPE_ARM_IPA_SIZE(type);
> > >      if (phys_shift) {
> > >          if (phys_shift > kvm_ipa_limit ||
> > > -            phys_shift < 32)
> > > +            phys_shift < KVM_PHYS_SHIFT_MIN)
> > >              return -EINVAL;
> > >      } else {
> > >          phys_shift = KVM_PHYS_SHIFT;
> >
> > This is not a KVM property, but an architectural one. If you
>
> Architectural property which suggest the minimum physical address shift
> supported on a platform, as indicated via ID_AA64MMFR0.PARANGE = 0x0 ?

That's the one.

        M.
--
Jazz is not dead. It just smells funny...