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hw/arm/virt: Enable MTE via a machine property

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Control this cpu feature via a machine property, much as we do
with secure=on, since both require specialized support in the
machine setup to be functional.

Default MTE to off, since this feature implies extra overhead.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200713213341.590275-2-richard.henderson@linaro.org
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This commit is contained in:
Richard Henderson 2020-07-20 10:25:36 +01:00 committed by Peter Maydell
parent 873ec69aeb
commit 6f4e1405b9
4 changed files with 49 additions and 15 deletions
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39
hw/arm/virt.c
View File

@ -1837,12 +1837,19 @@ static void machvirt_init(MachineState *machine)
OBJECT(secure_sysmem), &error_abort);
}
/*
* The cpu adds the property if and only if MemTag is supported.
* If it is, we must allocate the ram to back that up.
*/
if (object_property_find(cpuobj, "tag-memory", NULL)) {
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", NULL)) {
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);
@ -2061,6 +2068,20 @@ static void virt_set_ras(Object *obj, bool value, Error **errp)
vms->ras = value;
}
static bool virt_get_mte(Object *obj, Error **errp)
{
VirtMachineState *vms = VIRT_MACHINE(obj);
return vms->mte;
}
static void virt_set_mte(Object *obj, bool value, Error **errp)
{
VirtMachineState *vms = VIRT_MACHINE(obj);
vms->mte = value;
}
static char *virt_get_gic_version(Object *obj, Error **errp)
{
VirtMachineState *vms = VIRT_MACHINE(obj);
@ -2481,6 +2502,14 @@ static void virt_instance_init(Object *obj)
"Set on/off to enable/disable reporting host memory errors "
"to a KVM guest using ACPI and guest external abort exceptions");
/* MTE is disabled by default. */
vms->mte = false;
object_property_add_bool(obj, "mte", virt_get_mte, virt_set_mte);
object_property_set_description(obj, "mte",
"Set on/off to enable/disable emulating a "
"guest CPU which implements the ARM "
"Memory Tagging Extension");
vms->irqmap = a15irqmap;
virt_flash_create(vms);

1
include/hw/arm/virt.h
View File

@ -140,6 +140,7 @@ typedef struct {
bool its;
bool virt;
bool ras;
bool mte;
OnOffAuto acpi;
VirtGICType gic_version;
VirtIOMMUType iommu;

19
target/arm/cpu.c
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@ -1698,6 +1698,17 @@ static void arm_cpu_realizefn(DeviceState *dev, Error **errp)
cpu->id_pfr1 &= ~0xf000;
}
#ifndef CONFIG_USER_ONLY
if (cpu->tag_memory == NULL && cpu_isar_feature(aa64_mte, cpu)) {
/*
* Disable the MTE feature bits if we do not have tag-memory
* provided by the machine.
*/
cpu->isar.id_aa64pfr1 =
FIELD_DP64(cpu->isar.id_aa64pfr1, ID_AA64PFR1, MTE, 0);
}
#endif
/* MPU can be configured out of a PMSA CPU either by setting has-mpu
* to false or by setting pmsav7-dregion to 0.
*/
@ -1787,14 +1798,6 @@ static void arm_cpu_realizefn(DeviceState *dev, Error **errp)
cpu_address_space_init(cs, ARMASIdx_TagS, "cpu-tag-memory",
cpu->secure_tag_memory);
}
} else if (cpu_isar_feature(aa64_mte, cpu)) {
/*
* Since there is no tag memory, we can't meaningfully support MTE
* to its fullest. To avoid problems later, when we would come to
* use the tag memory, downgrade support to insns only.
*/
cpu->isar.id_aa64pfr1 =
FIELD_DP64(cpu->isar.id_aa64pfr1, ID_AA64PFR1, MTE, 1);
}
cpu_address_space_init(cs, ARMASIdx_NS, "cpu-memory", cs->memory);

5
target/arm/cpu64.c
View File

@ -646,8 +646,9 @@ static void aarch64_max_initfn(Object *obj)
t = cpu->isar.id_aa64pfr1;
t = FIELD_DP64(t, ID_AA64PFR1, BT, 1);
/*
* Begin with full support for MTE; will be downgraded to MTE=1
* during realize if the board provides no tag memory.
* Begin with full support for MTE. This will be downgraded to MTE=0
* during realize if the board provides no tag memory, much like
* we do for EL2 with the virtualization=on property.
*/
t = FIELD_DP64(t, ID_AA64PFR1, MTE, 2);
cpu->isar.id_aa64pfr1 = t;