Hi,
On Mon, Jun 21, 2021 at 12:18 PM Steven Price <steven.price@xxxxxxx> wrote:
>
> It's now safe for the VMM to enable MTE in a guest, so expose the
> capability to user space.
>
> Reviewed-by: Catalin Marinas <catalin.marinas@xxxxxxx>
> Signed-off-by: Steven Price <steven.price@xxxxxxx>
> ---
> arch/arm64/kvm/arm.c | 9 +++++++++
> arch/arm64/kvm/reset.c | 4 ++++
> arch/arm64/kvm/sys_regs.c | 3 +++
> 3 files changed, 16 insertions(+)
>
> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> index e720148232a0..28ce26a68f09 100644
> --- a/arch/arm64/kvm/arm.c
> +++ b/arch/arm64/kvm/arm.c
> @@ -93,6 +93,12 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm,
> r = 0;
> kvm->arch.return_nisv_io_abort_to_user = true;
> break;
> + case KVM_CAP_ARM_MTE:
> + if (!system_supports_mte() || kvm->created_vcpus)
> + return -EINVAL;
> + r = 0;
> + kvm->arch.mte_enabled = true;
> + break;
> default:
> r = -EINVAL;
> break;
> @@ -237,6 +243,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
> */
> r = 1;
> break;
> + case KVM_CAP_ARM_MTE:
> + r = system_supports_mte();
> + break;
> case KVM_CAP_STEAL_TIME:
> r = kvm_arm_pvtime_supported();
> break;
> diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
> index d37ebee085cf..9e6922b9503a 100644
> --- a/arch/arm64/kvm/reset.c
> +++ b/arch/arm64/kvm/reset.c
> @@ -244,6 +244,10 @@ int kvm_reset_vcpu(struct kvm_vcpu *vcpu)
> switch (vcpu->arch.target) {
> default:
> if (test_bit(KVM_ARM_VCPU_EL1_32BIT, vcpu->arch.features)) {
> + if (vcpu->kvm->arch.mte_enabled) {
> + ret = -EINVAL;
> + goto out;
> + }
> pstate = VCPU_RESET_PSTATE_SVC;
> } else {
> pstate = VCPU_RESET_PSTATE_EL1;
nit: I was wondering whether this check would be better suited in
kvm_vcpu_set_target, rather than here (kvm_reset_vcpu). kvm_reset_vcpu
is called by kvm_vcpu_set_target, but kvm_vcpu_set_target is where
checking for supported features happens. It might be better to group
all such checks together. I don't think that there is any risk of this
feature being toggled by the other call path to kvm_reset_vcpu (via
check_vcpu_requests).
Cheers,
/fuad
> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> index 5c75b24eae21..f6f126eb6ac1 100644
> --- a/arch/arm64/kvm/sys_regs.c
> +++ b/arch/arm64/kvm/sys_regs.c
> @@ -1312,6 +1312,9 @@ static bool access_ccsidr(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
> static unsigned int mte_visibility(const struct kvm_vcpu *vcpu,
> const struct sys_reg_desc *rd)
> {
> + if (kvm_has_mte(vcpu->kvm))
> + return 0;
> +
> return REG_HIDDEN;
> }
>
> --
> 2.20.1
>
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