On Thu, Feb 08, 2024 at 01:00:59PM +0000, Catalin Marinas wrote:
> On Thu, Feb 08, 2024 at 02:16:49AM +0530, ankita@xxxxxxxxxx wrote:
> > diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
> > index c651df904fe3..2a893724ee9b 100644
> > --- a/arch/arm64/kvm/hyp/pgtable.c
> > +++ b/arch/arm64/kvm/hyp/pgtable.c
> > @@ -717,15 +717,28 @@ void kvm_tlb_flush_vmid_range(struct kvm_s2_mmu *mmu,
> > static int stage2_set_prot_attr(struct kvm_pgtable *pgt, enum kvm_pgtable_prot prot,
> > kvm_pte_t *ptep)
> > {
> > - bool device = prot & KVM_PGTABLE_PROT_DEVICE;
> > - kvm_pte_t attr = device ? KVM_S2_MEMATTR(pgt, DEVICE_nGnRE) :
> > - KVM_S2_MEMATTR(pgt, NORMAL);
> > + kvm_pte_t attr;
> > u32 sh = KVM_PTE_LEAF_ATTR_LO_S2_SH_IS;
> >
> > + switch (prot & (KVM_PGTABLE_PROT_DEVICE |
> > + KVM_PGTABLE_PROT_NORMAL_NC)) {
> > + case 0:
> > + attr = KVM_S2_MEMATTR(pgt, NORMAL);
> > + break;
> > + case KVM_PGTABLE_PROT_DEVICE:
> > + if (prot & KVM_PGTABLE_PROT_X)
> > + return -EINVAL;
> > + attr = KVM_S2_MEMATTR(pgt, DEVICE_nGnRE);
> > + break;
> > + case KVM_PGTABLE_PROT_NORMAL_NC:
> > + attr = KVM_S2_MEMATTR(pgt, NORMAL_NC);
> > + break;
>
> Does it make sense to allow executable here as well? I don't think it's
> harmful but not sure there's a use-case for it either.
Ah, we should just return EINVAL for that too.
I get that the memory attribute itself is not problematic, but since
we're only using this thing for MMIO it'd be a rather massive
bug in KVM... We reject attempts to do this earlier in user_mem_abort().
If, for some reason, we wanted to do Normal-NC actual memory then we
would need to make sure that KVM does the appropriate cache maintenance
at map / unmap.
--
Thanks,
Oliver
