Extend the 'mte' property for the virt machine to cover KVM as
well. For KVM, we don't allocate tag memory, but instead enable
the capability.
If MTE has been enabled, we need to disable migration, as we do not
yet have a way to migrate the tags as well. Therefore, MTE will stay
off with KVM unless requested explicitly.
This patch is rework of commit b320e21c48ce64853904bea6631c0158cc2ef227
which broke TCG since it made the TCG -cpu max
report the presence of MTE to the guest even if the board hadn't
enabled MTE by wiring up the tag RAM. This meant that if the guest
then tried to use MTE QEMU would segfault accessing the
non-existent tag RAM.
Signed-off-by: Cornelia Huck <coh...@redhat.com>
Signed-off-by: Ganapatrao Kulkarni <gankulka...@os.amperecomputing.com>
---
Changes since V2:
Updated with review comments.
Changes since V1:
Added code to enable MTE before reading register
id_aa64pfr1 (unmasked MTE bits).
This patch is boot tested on ARM64 with KVM and on X86 with TCG for
mte=on
and default case(i.e, no mte).
hw/arm/virt.c | 72
++++++++++++++++++++++++++------------------
target/arm/cpu.c | 11 +++++--
target/arm/cpu.h | 2 ++
target/arm/kvm.c | 57 +++++++++++++++++++++++++++++++++++
target/arm/kvm_arm.h | 19 ++++++++++++
5 files changed, 129 insertions(+), 32 deletions(-)
diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index 7934b23651..a33af7d996 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -2211,7 +2211,7 @@ static void machvirt_init(MachineState *machine)
exit(1);
}
- if (vms->mte && (kvm_enabled() || hvf_enabled())) {
+ if (vms->mte && hvf_enabled()) {
error_report("mach-virt: %s does not support providing "
"MTE to the guest CPU",
current_accel_name());
@@ -2281,39 +2281,51 @@ static void machvirt_init(MachineState
*machine)
}
if (vms->mte) {
- /* Create the memory region only once, but link to all
cpus. */
- if (!tag_sysmem) {
- /*
- * The property exists only if MemTag is supported.
- * If it is, we must allocate the ram to back that up.
- */
- if (!object_property_find(cpuobj, "tag-memory")) {
- error_report("MTE requested, but not supported "
- "by the guest CPU");
- exit(1);
+ if (tcg_enabled()) {
+ /* Create the memory region only once, but link to
all cpus. */
+ if (!tag_sysmem) {
+ /*
+ * The property exists only if MemTag is
supported.
+ * If it is, we must allocate the ram to back
that up.
+ */
+ if (!object_property_find(cpuobj, "tag-memory")) {
+ error_report("MTE requested, but not
supported "
+ "by the guest CPU");
+ exit(1);
+ }
+
+ tag_sysmem = g_new(MemoryRegion, 1);
+ memory_region_init(tag_sysmem, OBJECT(machine),
+ "tag-memory", UINT64_MAX / 32);
+
+ if (vms->secure) {
+ secure_tag_sysmem = g_new(MemoryRegion, 1);
+ memory_region_init(secure_tag_sysmem,
OBJECT(machine),
+ "secure-tag-memory",
+ UINT64_MAX / 32);
+
+ /* As with ram, secure-tag takes precedence
over tag. */
+ memory_region_add_subregion_overlap(secure_tag_sysmem,
+ 0, tag_sysmem, -1);
+ }
}
- tag_sysmem = g_new(MemoryRegion, 1);
- memory_region_init(tag_sysmem, OBJECT(machine),
- "tag-memory", UINT64_MAX / 32);
-
+ object_property_set_link(cpuobj, "tag-memory",
+ OBJECT(tag_sysmem),
&error_abort);
if (vms->secure) {
- secure_tag_sysmem = g_new(MemoryRegion, 1);
- memory_region_init(secure_tag_sysmem,
OBJECT(machine),
- "secure-tag-memory",
UINT64_MAX / 32);
-
- /* As with ram, secure-tag takes precedence
over tag. */
- memory_region_add_subregion_overlap(secure_tag_sysmem, 0,
- tag_sysmem, -1);
+ object_property_set_link(cpuobj,
"secure-tag-memory",
+ OBJECT(secure_tag_sysmem),
+ &error_abort);
}
- }
-
- object_property_set_link(cpuobj, "tag-memory",
OBJECT(tag_sysmem),
- &error_abort);
- if (vms->secure) {
- object_property_set_link(cpuobj, "secure-tag-memory",
- OBJECT(secure_tag_sysmem),
- &error_abort);
+ } else if (kvm_enabled()) {
+ if (!kvm_arm_mte_supported()) {
+ error_report("MTE requested, but not supported
by KVM");
+ exit(1);
+ }
+ kvm_arm_enable_mte(cpuobj, &error_abort);
+ } else {
+ error_report("MTE requested, but not supported ");
+ exit(1);
}
}
diff --git a/target/arm/cpu.c b/target/arm/cpu.c
index 19191c2391..8a2fc471ce 100644
--- a/target/arm/cpu.c
+++ b/target/arm/cpu.c
@@ -2390,14 +2390,21 @@ static void arm_cpu_realizefn(DeviceState
*dev, Error **errp)
#ifndef CONFIG_USER_ONLY
/*
- * If we do not have tag-memory provided by the machine,
+ * If we do not have tag-memory provided by the TCG,
* reduce MTE support to instructions enabled at EL0.
* This matches Cortex-A710 BROADCASTMTE input being LOW.
*/
- if (cpu->tag_memory == NULL) {
+ if (tcg_enabled() && cpu->tag_memory == NULL) {
cpu->isar.id_aa64pfr1 =
FIELD_DP64(cpu->isar.id_aa64pfr1, ID_AA64PFR1,
MTE, 1);
}
+
+ /*
+ * Clear MTE bits, if not enabled in KVM mode.
+ */
+ if (kvm_enabled() && !cpu->kvm_mte) {
+ FIELD_DP64(cpu->isar.id_aa64pfr1, ID_AA64PFR1, MTE,
0);
+ }
