KVM: arm64: Expose KVM_ARM_CAP_MTE

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@arm.com>
Signed-off-by: Steven Price <steven.price@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210621111716.37157-5-steven.price@arm.com

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index e720148..28ce26a 100644 (file)
--- 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 d37ebee..cba7872 100644 (file)
--- a/arch/arm64/kvm/reset.c
+++ b/arch/arm64/kvm/reset.c
@@ -176,6 +176,10 @@ static bool vcpu_allowed_register_width(struct kvm_vcpu *vcpu)
        if (!cpus_have_const_cap(ARM64_HAS_32BIT_EL1) && is32bit)
                return false;
 
+       /* MTE is incompatible with AArch32 */
+       if (kvm_has_mte(vcpu->kvm) && is32bit)
+               return false;
+
        /* Check that the vcpus are either all 32bit or all 64bit */
        kvm_for_each_vcpu(i, tmp, vcpu->kvm) {
                if (vcpu_has_feature(tmp, KVM_ARM_VCPU_EL1_32BIT) != is32bit)

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 5c75b24..f6f126e 100644 (file)
--- 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;
 }