From 673638f434ee4a00319e254ade338c57618d6f7e Mon Sep 17 00:00:00 2001
From: Steven Price <steven.price@arm.com>
Date: Mon, 21 Jun 2021 12:17:14 +0100
Subject: [PATCH] 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
---
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 e720148232a06..28ce26a68f09c 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 d37ebee085cfe..cba7872d69a85 100644
--- 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 5c75b24eae219..f6f126eb6ac13 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;
}
--
2.30.2