On 2022-03-01 18:55:51 [+0100], To kvm@xxxxxxxxxxxxxxx wrote:
> From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Date: Sun, 6 Nov 2011 12:26:18 +0100
>
> Non constant TSC is a nightmare on bare metal already, but with
> virtualization it becomes a complete disaster because the workarounds
> are horrible latency wise. That's also a preliminary for running RT in
> a guest on top of a RT host.
>
> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
ping.
> ---
> arch/x86/kvm/x86.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 82a9dcd8c67fe..54d2090d04e7a 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -8826,6 +8826,12 @@ int kvm_arch_init(void *opaque)
> goto out;
> }
>
> + if (IS_ENABLED(CONFIG_PREEMPT_RT) && !boot_cpu_has(X86_FEATURE_CONSTANT_TSC)) {
> + pr_err("RT requires X86_FEATURE_CONSTANT_TSC\n");
> + r = -EOPNOTSUPP;
> + goto out;
> + }
> +
> r = -ENOMEM;
>
> x86_emulator_cache = kvm_alloc_emulator_cache();
> --
> 2.35.1
>
