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

Message ID 20230823131350.114942-37-alexandru.elisei@arm.com (mailing list archive)
State New
Headers show
Series [RFC,01/37] mm: page_alloc: Rename gfp_to_alloc_flags_cma -> gfp_to_alloc_flags_fast | expand

Commit Message

Alexandru Elisei Aug. 23, 2023, 1:13 p.m. UTC 
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(-)
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Patch

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();