Re: [PATCH v2 4/4] KVM: Do compatibility checks on hotplugged CPUs

From: Sean Christopherson <seanjc@google.com>
To: Chao Gao <chao.gao@intel.com>
Cc: kvm@vger.kernel.org, pbonzini@redhat.com, kevin.tian@intel.com,
	tglx@linutronix.de, Vitaly Kuznetsov <vkuznets@redhat.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 4/4] KVM: Do compatibility checks on hotplugged CPUs
Date: Wed, 9 Feb 2022 00:36:37 +0000	[thread overview]
Message-ID: <YgMMlaMnjQRqwW6w@google.com> (raw)
In-Reply-To: <20220118064430.3882337-5-chao.gao@intel.com>

On Tue, Jan 18, 2022, Chao Gao wrote:
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 528741601122..83f87fb1fa0a 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -4858,7 +4858,13 @@ static void hardware_enable_nolock(void *junk)
>  
>  static int kvm_online_cpu(unsigned int cpu)
>  {
> -	int ret = 0;
> +	int ret;
> +
> +	ret = kvm_arch_check_processor_compat();
> +	if (ret) {
> +		pr_warn("kvm: CPU%d is incompatible with online CPUs", cpu);

Hmm, I'd say omit the pr_warn() here too and instead add a pr_err() for the
setup_vmcs_config() path in vmx_check_processor_compat().

> +		return ret;
> +	}