[PATCH RFC 36/37] KVM: arm64: Disable MTE is tag storage is enabled

Alexandru Elisei
2023-08-23T13:18:05Z

KVM allows MTE enabled VMs to be created when the backing memory is does
not have MTE enabled. Without changes to how KVM allocates memory for a
VM, it is impossible to discern when the corresponding tag storage needs to
be reserved.

For now, disable MTE in KVM if tag storage is enabled.

Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
---
arch/arm64/kvm/arm.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 72dc53a75d1c..1f39c2d5223d 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -38,6 +38,7 @@
#include <asm/kvm_mmu.h>
#include <asm/kvm_pkvm.h>
#include <asm/kvm_emulate.h>
+#include <asm/memory_metadata.h>
#include <asm/sections.h>

#include <kvm/arm_hypercalls.h>
@@ -85,7 +86,8 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm,
break;
case KVM_CAP_ARM_MTE:
mutex_lock(&kvm->lock);
- if (!system_supports_mte() || kvm->created_vcpus) {
+ if (!system_supports_mte() || metadata_storage_enabled() ||
+ kvm->created_vcpus) {
r = -EINVAL;
} else {
r = 0;
@@ -277,7 +279,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
r = 1;
break;
case KVM_CAP_ARM_MTE:
- r = system_supports_mte();
+ r = system_supports_mte() && !metadata_storage_enabled();
break;
case KVM_CAP_STEAL_TIME:
r = kvm_arm_pvtime_supported();
--
2.41.0