[PATCH v4 04/14] KVM: arm64: Propagate and use esr in s2fd when handling guest aborts

[Fuad Tabba]

On Wed, 23 Sept 2026 at 16:16, Lorenzo Stoakes (ARM) <ljs at kernel.org> wrote:
>
> kvm_handle_guest_abort() establishes a kvm_s2_fault_desc data structure,
> s2fd, to store and propagate state to either pkvm_mem_abort(), gmem_abort()
> or user_mem_abort() handlers.
>
> Each of these, however, examines the Exception Syndrome Register (ESR) via
> s2fd->vcpu.
>
> Introduce an s2fd->esr field to abstract this and propagate it to callers.
>
> The value of this (beyond refactoring) is to be able to later generate
> faults with a synthetic esr, specifically to implement stage 2 page table
> pre-faulting.
>
> Abort handlers which use kvm_s2_fault_desc - gmem_abort() and
> user_mem_abort() - now only reference s2fd->esr and do not look it up in
> any other way, which makes it safe to pass a synthetic s2fd->esr value to
> these functions.
>
> No functional change intended.
>
> Reviewed-by: Oliver Upton <oupton at kernel.org>
> Signed-off-by: Lorenzo Stoakes (ARM) <ljs at kernel.org>

Reviewed-by: Fuad Tabba <fuad.tabba at linux.dev>

Cheers,
/fuad

> ---
>  arch/arm64/kvm/mmu.c | 12 +++++++-----
>  1 file changed, 7 insertions(+), 5 deletions(-)
>
> diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
> index 5e10a4cd31ea..cb677ab76484 100644
> --- a/arch/arm64/kvm/mmu.c
> +++ b/arch/arm64/kvm/mmu.c
> @@ -1655,21 +1655,22 @@ struct kvm_s2_fault_desc {
>         struct kvm_s2_trans     *nested;
>         struct kvm_memory_slot  *memslot;
>         unsigned long           hva;
> +       unsigned long           esr;
>  };
>
>  static bool kvm_s2_fault_is_perm(const struct kvm_s2_fault_desc *s2fd)
>  {
> -       return esr_fsc_is_permission_fault(kvm_vcpu_get_esr(s2fd->vcpu));
> +       return esr_fsc_is_permission_fault(s2fd->esr);
>  }
>
>  static bool kvm_s2_fault_is_exec(const struct kvm_s2_fault_desc *s2fd)
>  {
> -       return esr_abt_is_exec_fault(kvm_vcpu_get_esr(s2fd->vcpu));
> +       return esr_abt_is_exec_fault(s2fd->esr);
>  }
>
>  static bool kvm_s2_fault_is_write(const struct kvm_s2_fault_desc *s2fd)
>  {
> -       return esr_abt_is_write_fault(kvm_vcpu_get_esr(s2fd->vcpu));
> +       return esr_abt_is_write_fault(s2fd->esr);
>  }
>
>  static u64 kvm_s2_perm_fault_granule(const struct kvm_s2_fault_desc *s2fd)
> @@ -1678,7 +1679,7 @@ static u64 kvm_s2_perm_fault_granule(const struct kvm_s2_fault_desc *s2fd)
>
>         if (!kvm_s2_fault_is_perm(s2fd))
>                 return 0;
> -       level = kvm_vcpu_get_esr(s2fd->vcpu) & ESR_ELx_FSC_LEVEL;
> +       level = s2fd->esr & ESR_ELx_FSC_LEVEL;
>         return BIT(ARM64_HW_PGTABLE_LEVEL_SHIFT(level));
>  }
>
> @@ -2067,7 +2068,7 @@ static int kvm_s2_fault_compute_prot(const struct kvm_s2_fault_desc *s2fd,
>          * and trigger the exception here. Since the memslot is valid, inject
>          * the fault back to the guest.
>          */
> -       if (esr_fsc_is_excl_atomic_fault(kvm_vcpu_get_esr(s2fd->vcpu))) {
> +       if (esr_fsc_is_excl_atomic_fault(s2fd->esr)) {
>                 kvm_inject_dabt_excl_atomic(s2fd->vcpu, kvm_vcpu_get_hfar(s2fd->vcpu));
>                 return 1;
>         }
> @@ -2518,6 +2519,7 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu)
>                 .nested         = nested,
>                 .memslot        = memslot,
>                 .hva            = hva,
> +               .esr            = esr,
>         };
>
>         if (kvm_vm_is_protected(vcpu->kvm)) {
>
> --
> 2.55.0
>