From: Marc Zyngier 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 Signed-off-by: Andre Przywara --- 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