From: Marc Zyngier <maz@xxxxxxxxxx>
KVM now allows to offset the arch timer counter values reported to a
guest, via a per-VM ioctl. This is conceptually similar to the effects
of CNTVOFF_EL2, but applies to both the emulated physical and virtual
counter, and also to all VCPUs.
Add a command line option to allow setting this value when creating a VM.
Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
---
arm64/include/kvm/kvm-config-arch.h | 3 +++
arm64/kvm.c | 17 +++++++++++++++++
2 files changed, 20 insertions(+)
diff --git a/arm64/include/kvm/kvm-config-arch.h b/arm64/include/kvm/kvm-config-arch.h
index a1dac28e6..44c43367b 100644
--- a/arm64/include/kvm/kvm-config-arch.h
+++ b/arm64/include/kvm/kvm-config-arch.h
@@ -14,6 +14,7 @@ struct kvm_config_arch {
u64 kaslr_seed;
enum irqchip_type irqchip;
u64 fw_addr;
+ u64 counter_offset;
unsigned int sve_max_vq;
bool no_pvtime;
};
@@ -59,6 +60,8 @@ int sve_vl_parser(const struct option *opt, const char *arg, int unset);
irqchip_parser, NULL), \
OPT_U64('\0', "firmware-address", &(cfg)->fw_addr, \
"Address where firmware should be loaded"), \
+ OPT_U64('\0', "counter-offset", &(cfg)->counter_offset, \
+ "Specify the counter offset, defaulting to 0"), \
OPT_BOOLEAN('\0', "nested", &(cfg)->nested_virt, \
"Start VCPUs in EL2 (for nested virt)"),
diff --git a/arm64/kvm.c b/arm64/kvm.c
index 23b4dab1f..6e971dd78 100644
--- a/arm64/kvm.c
+++ b/arm64/kvm.c
@@ -119,6 +119,22 @@ static void kvm__arch_enable_mte(struct kvm *kvm)
pr_debug("MTE capability enabled");
}
+static void kvm__arch_set_counter_offset(struct kvm *kvm)
+{
+ struct kvm_arm_counter_offset offset = {
+ .counter_offset = kvm->cfg.arch.counter_offset,
+ };
+
+ if (!kvm->cfg.arch.counter_offset)
+ return;
+
+ if (!kvm__supports_extension(kvm, KVM_CAP_COUNTER_OFFSET))
+ die("No support for global counter offset");
+
+ if (ioctl(kvm->vm_fd, KVM_ARM_SET_COUNTER_OFFSET, &offset))
+ die_perror("KVM_ARM_SET_COUNTER_OFFSET");
+}
+
void kvm__arch_init(struct kvm *kvm)
{
/* Create the virtual GIC. */
@@ -126,6 +142,7 @@ void kvm__arch_init(struct kvm *kvm)
die("Failed to create virtual GIC");
kvm__arch_enable_mte(kvm);
+ kvm__arch_set_counter_offset(kvm);
}
static u64 kvm__arch_get_payload_region_size(struct kvm *kvm)
--
2.25.1
