On 10/08/2022 20:30, Peter Collingbourne wrote: > Previously we allowed creating a memslot containing a private mapping that > was not VM_MTE_ALLOWED, but would later reject KVM_RUN with -EFAULT. Now > we reject the memory region at memslot creation time. > > Since this is a minor tweak to the ABI (a VMM that created one of > these memslots would fail later anyway), no VMM to my knowledge has > MTE support yet, and the hardware with the necessary features is not > generally available, we can probably make this ABI change at this point. > > Signed-off-by: Peter Collingbourne <[email protected]>
Reviewed-by: Steven Price <[email protected]> > --- > arch/arm64/kvm/mmu.c | 25 ++++++++++++++++--------- > 1 file changed, 16 insertions(+), 9 deletions(-) > > diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c > index 750a69a97994..d54be80e31dd 100644 > --- a/arch/arm64/kvm/mmu.c > +++ b/arch/arm64/kvm/mmu.c > @@ -1073,6 +1073,19 @@ static void sanitise_mte_tags(struct kvm *kvm, > kvm_pfn_t pfn, > } > } > > +static bool kvm_vma_mte_allowed(struct vm_area_struct *vma) > +{ > + /* > + * VM_SHARED mappings are not allowed with MTE to avoid races > + * when updating the PG_mte_tagged page flag, see > + * sanitise_mte_tags for more details. > + */ > + if (vma->vm_flags & VM_SHARED) > + return false; > + > + return vma->vm_flags & VM_MTE_ALLOWED; > +} > + > static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, > struct kvm_memory_slot *memslot, unsigned long hva, > unsigned long fault_status) > @@ -1249,9 +1262,8 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, > phys_addr_t fault_ipa, > } > > if (fault_status != FSC_PERM && !device && kvm_has_mte(kvm)) { > - /* Check the VMM hasn't introduced a new VM_SHARED VMA */ > - if ((vma->vm_flags & VM_MTE_ALLOWED) && > - !(vma->vm_flags & VM_SHARED)) { > + /* Check the VMM hasn't introduced a new disallowed VMA */ > + if (kvm_vma_mte_allowed(vma)) { > sanitise_mte_tags(kvm, pfn, vma_pagesize); > } else { > ret = -EFAULT; > @@ -1695,12 +1707,7 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm, > if (!vma) > break; > > - /* > - * VM_SHARED mappings are not allowed with MTE to avoid races > - * when updating the PG_mte_tagged page flag, see > - * sanitise_mte_tags for more details. > - */ > - if (kvm_has_mte(kvm) && vma->vm_flags & VM_SHARED) { > + if (kvm_has_mte(kvm) && !kvm_vma_mte_allowed(vma)) { > ret = -EINVAL; > break; > } _______________________________________________ kvmarm mailing list [email protected] https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
