Re: [PATCH v3] KVM: arm64: Fix protected VM fault on system with pages larger than 4K

[Suzuki K Poulose <suzuki.poulose@arm.com>]

On 15/09/2026 10:16, Vincent Donnefort wrote:
> Just like commit 08f97454b7fa ("KVM: arm64: Fix protected mode handling
> of pages larger than 4kB") fixed the boot of non-protected VMs on system
> larger than 4K pages, align the fault IPA down to the page-size for
> protected VMs.
> 
> To paraphrase Marc, pkvm_pgtable_stage2_map() assumes the address passed
> as a parameter is aligned to the size of the intended mapping, while
> HPFAR_EL2 gives the IPA minus the bottom 12 bits, regardless of the
> system page size configuration.
> 
> Add a check at the start of pkvm_pgtable_stage2_map() as we do not
> support !PAGE_ALIGNED arguments and ensure callers pass a page-aligned
> IPA.
> 
> Fixes: ea03466e806f ("KVM: arm64: Handle aborts from protected VMs")
> Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
> ---
>   arch/arm64/kvm/mmu.c  | 12 +++++++-----
>   arch/arm64/kvm/pkvm.c |  3 +++
>   2 files changed, 10 insertions(+), 5 deletions(-)
> 
> Changelog:
> 
> v3:
>    - Fix nested case in gmem_abort() (Sashiko)
> 
> v2: https://lore.kernel.org/all/20260914075839.4019904-1-vdonnefort@google.com/
> 
>    - Use gfn_to_gpa(gfn)
>    - Drop "phys" from the PAGE_ALIGNED check, it isn't a requirement.
>    - Fix gmem_abort() as well (Sashiko)
> 
> v1: https://lore.kernel.org/all/20260913173516.3122436-1-vdonnefort@google.com/
> 
> diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
> index 9ba86450fe4a..e199dd339583 100644
> --- a/arch/arm64/kvm/mmu.c
> +++ b/arch/arm64/kvm/mmu.c
> @@ -1610,6 +1610,7 @@ static int gmem_abort(const struct kvm_s2_fault_desc *s2fd)
>   	bool write_fault, exec_fault;
>   	bool perm_fault = kvm_vcpu_trap_is_permission_fault(s2fd->vcpu);
>   	enum kvm_pgtable_walk_flags flags = KVM_PGTABLE_WALK_SHARED;
> +	phys_addr_t ipa = ALIGN_DOWN(s2fd->fault_ipa, PAGE_SIZE);
>   	enum kvm_pgtable_prot prot = KVM_PGTABLE_PROT_R;
>   	struct kvm_pgtable *pgt = s2fd->vcpu->arch.hw_mmu->pgt;
>   	unsigned long mmu_seq;
> @@ -1672,12 +1673,12 @@ static int gmem_abort(const struct kvm_s2_fault_desc *s2fd)
>   		 * PTE, which will be preserved.
>   		 */
>   		prot &= ~KVM_NV_GUEST_MAP_SZ;
> -		ret = KVM_PGT_FN(kvm_pgtable_stage2_relax_perms)(pgt, s2fd->fault_ipa,
> +		ret = KVM_PGT_FN(kvm_pgtable_stage2_relax_perms)(pgt, ipa,
>   								 prot, flags);
>   	} else {
> -		ret = KVM_PGT_FN(kvm_pgtable_stage2_map)(pgt, s2fd->fault_ipa, PAGE_SIZE,
> -							 __pfn_to_phys(pfn), prot,
> -							 memcache, flags);
> +		ret = KVM_PGT_FN(kvm_pgtable_stage2_map)(pgt, ipa, PAGE_SIZE,
> +							 __pfn_to_phys(pfn),
> +							 prot, memcache, flags);
>   	}
>   
>   out_unlock:
> @@ -1710,6 +1711,7 @@ static int pkvm_mem_abort(const struct kvm_s2_fault_desc *s2fd)
>   	unsigned int flags = FOLL_HWPOISON | FOLL_LONGTERM | FOLL_WRITE;
>   	struct kvm_vcpu *vcpu = s2fd->vcpu;
>   	struct kvm_pgtable *pgt = vcpu->arch.hw_mmu->pgt;
> +	gfn_t gfn = gpa_to_gfn(s2fd->fault_ipa);

minor nit: Is there any reason why this is not consistent with the 
gmem_abort() ? i.e., using gfn instead of "ipa" ?

The patch as such looks correct to me. So, either way :

Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>


>   	struct mm_struct *mm = current->mm;
>   	struct kvm *kvm = vcpu->kvm;
>   	void *hyp_memcache;
> @@ -1756,7 +1758,7 @@ static int pkvm_mem_abort(const struct kvm_s2_fault_desc *s2fd)
>   	}
>   
>   	write_lock(&kvm->mmu_lock);
> -	ret = pkvm_pgtable_stage2_map(pgt, s2fd->fault_ipa, PAGE_SIZE,
> +	ret = pkvm_pgtable_stage2_map(pgt, gfn_to_gpa(gfn), PAGE_SIZE,
>   				      page_to_phys(page), KVM_PGTABLE_PROT_RWX,
>   				      hyp_memcache, 0);
>   	write_unlock(&kvm->mmu_lock);
> diff --git a/arch/arm64/kvm/pkvm.c b/arch/arm64/kvm/pkvm.c
> index 8e4c6e4bec12..b7340c430ed6 100644
> --- a/arch/arm64/kvm/pkvm.c
> +++ b/arch/arm64/kvm/pkvm.c
> @@ -414,6 +414,9 @@ int pkvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size,
>   	u64 end = addr + size;
>   	int ret;
>   
> +	if (!PAGE_ALIGNED(addr | size))
> +		return -EINVAL;
> +
>   	lockdep_assert_held_write(&kvm->mmu_lock);
>   	mapping = pkvm_mapping_iter_first(&pgt->pkvm_mappings, addr, end - 1);
>   
> 
> base-commit: df2908090cda368b01ff43709f51890076c56157