linux-kernel - Re: [PATCH v5 2/4] KVM: LAPIC: Inject timer interrupt via posted interrupt

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Message-ID: <587f329a-4920-fcbf-b2b1-9265a1d6d364@redhat.com>
Date:   Fri, 5 Jul 2019 14:37:44 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Wanpeng Li <kernellwp@...il.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Cc:     Radim Krčmář <rkrcmar@...hat.com>,
        Marcelo Tosatti <mtosatti@...hat.com>
Subject: Re: [PATCH v5 2/4] KVM: LAPIC: Inject timer interrupt via posted
 interrupt

On 21/06/19 11:40, Wanpeng Li wrote:
> +bool __read_mostly pi_inject_timer = 0;
> +module_param(pi_inject_timer, bool, S_IRUGO | S_IWUSR);
> +
>  #define KVM_NR_SHARED_MSRS 16
>  
>  struct kvm_shared_msrs_global {
> @@ -7032,6 +7036,7 @@ int kvm_arch_init(void *opaque)
>  		host_xcr0 = xgetbv(XCR_XFEATURE_ENABLED_MASK);
>  
>  	kvm_lapic_init();
> +	pi_inject_timer = housekeeping_enabled(HK_FLAG_TIMER);

This overwrites whatever the user specified, so perhaps:

u8 __read_mostly pi_inject_timer = -1;
module_param(pi_inject_timer, bool, S_IRUGO | S_IWUSR);

...
	if (pi_inject_timer == -1)
		pi_inject_timer = housekeeping_enabled(HK_FLAG_TIMER);

Also, do you want to disable the preemption timer if pi_inject_timer and
enable_apicv are both true?

Paolo