[PATCH v15 5/7] KVM: arm64: Expose KVM_ARM_CAP_MTE

Steven Price
2021-06-14T09:06:04Z

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>
---
arch/arm64/kvm/arm.c | 9 +++++++++
arch/arm64/kvm/reset.c | 3 ++-
arch/arm64/kvm/sys_regs.c | 3 +++
3 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 1cb39c0803a4..e89a5e275e25 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 956cdc240148..50635eacfa43 100644
--- a/arch/arm64/kvm/reset.c
+++ b/arch/arm64/kvm/reset.c
@@ -220,7 +220,8 @@ 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 (!cpus_have_const_cap(ARM64_HAS_32BIT_EL1)) {
+ if (!cpus_have_const_cap(ARM64_HAS_32BIT_EL1) ||
+ vcpu->kvm->arch.mte_enabled) {
ret = -EINVAL;
goto out;
}
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 440315a556c2..d4e1c1b1a08d 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;