On Fri, 24 Jul 2020 15:35:04 +0100,
Will Deacon <will@xxxxxxxxxx> wrote:
>
> In preparation for handling stage-2 faults on stage-1 page-table walks
> earlier, move the 'invalid syndrome' logic out of io_mem_abort() and
> into its own function, which can be called from kvm_handle_guest_abort()
> directly.
>
> Cc: Marc Zyngier <maz@xxxxxxxxxx>
> Cc: Quentin Perret <qperret@xxxxxxxxxx>
> Signed-off-by: Will Deacon <will@xxxxxxxxxx>
> ---
> arch/arm64/kvm/mmio.c | 22 ----------------------
> arch/arm64/kvm/mmu.c | 32 ++++++++++++++++++++++++++++++++
> 2 files changed, 32 insertions(+), 22 deletions(-)
>
> diff --git a/arch/arm64/kvm/mmio.c b/arch/arm64/kvm/mmio.c
> index b54ea5aa6c06..45a630e480e1 100644
> --- a/arch/arm64/kvm/mmio.c
> +++ b/arch/arm64/kvm/mmio.c
> @@ -136,28 +136,6 @@ int io_mem_abort(struct kvm_vcpu *vcpu, struct kvm_run *run,
> int len;
> u8 data_buf[8];
>
> - /*
> - * No valid syndrome? Ask userspace for help if it has
> - * volunteered to do so, and bail out otherwise.
> - */
> - if (!kvm_vcpu_dabt_isvalid(vcpu)) {
> - if (vcpu->kvm->arch.return_nisv_io_abort_to_user) {
> - run->exit_reason = KVM_EXIT_ARM_NISV;
> - run->arm_nisv.esr_iss = kvm_vcpu_dabt_iss_nisv_sanitized(vcpu);
> - run->arm_nisv.fault_ipa = fault_ipa;
> - return 0;
> - }
> -
> - kvm_pr_unimpl("Data abort outside memslots with no valid syndrome info\n");
> - return -ENOSYS;
> - }
> -
> - /* Page table accesses IO mem: tell guest to fix its TTBR */
> - if (kvm_vcpu_dabt_iss1tw(vcpu)) {
> - kvm_inject_dabt(vcpu, kvm_vcpu_get_hfar(vcpu));
> - return 1;
> - }
> -
> /*
> * Prepare MMIO operation. First decode the syndrome data we get
> * from the CPU. Then try if some in-kernel emulation feels
> diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
> index 73e62d360a36..adb933ecd177 100644
> --- a/arch/arm64/kvm/mmu.c
> +++ b/arch/arm64/kvm/mmu.c
> @@ -2046,6 +2046,20 @@ static void handle_access_fault(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa)
> kvm_set_pfn_accessed(pfn);
> }
>
> +static int handle_error_invalid_dabt(struct kvm_vcpu *vcpu, struct kvm_run *run,
Nit: why the "_error_"? There isn't any error here, only an awkward
part of the architecture. I'd rather see something like
handle_nisv_dabt(), which matches what this function actually does.
> + phys_addr_t fault_ipa)
> +{
> + if (!vcpu->kvm->arch.return_nisv_io_abort_to_user) {
> + kvm_pr_unimpl("Data abort outside memslots with no valid syndrome info\n");
> + return -ENOSYS;
> + }
> +
> + run->exit_reason = KVM_EXIT_ARM_NISV;
> + run->arm_nisv.esr_iss = kvm_vcpu_dabt_iss_nisv_sanitized(vcpu);
> + run->arm_nisv.fault_ipa = fault_ipa;
> + return 0;
> +}
> +
> /**
> * kvm_handle_guest_abort - handles all 2nd stage aborts
> * @vcpu: the VCPU pointer
> @@ -2133,6 +2147,21 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu, struct kvm_run *run)
> * of the page size.
> */
> fault_ipa |= kvm_vcpu_get_hfar(vcpu) & ((1 << 12) - 1);
> +
> + /*
> + * No valid syndrome? Ask userspace for help if it has
> + * volunteered to do so, and bail out otherwise.
> + */
> + if (!kvm_vcpu_dabt_isvalid(vcpu)) {
> + ret = handle_error_invalid_dabt(vcpu, run, fault_ipa);
> + goto out_unlock;
> + }
> +
> + if (kvm_vcpu_dabt_iss1tw(vcpu)) {
> + ret = -ENXIO;
> + goto out;
> + }
> +
> ret = io_mem_abort(vcpu, run, fault_ipa);
> goto out_unlock;
> }
> @@ -2153,6 +2182,9 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu, struct kvm_run *run)
> if (ret == -ENOEXEC) {
> kvm_inject_pabt(vcpu, kvm_vcpu_get_hfar(vcpu));
> ret = 1;
> + } else if (ret == -ENXIO) {
> + kvm_inject_dabt(vcpu, kvm_vcpu_get_hfar(vcpu));
> + ret = 1;
> }
> out_unlock:
> srcu_read_unlock(&vcpu->kvm->srcu, idx);
> --
> 2.28.0.rc0.142.g3c755180ce-goog
>
>
Otherwise looks OK.
M.
--
Without deviation from the norm, progress is not possible.
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