linux-kernel - Re: [PATCH v2 3/4] x86/kvm/hyper-v: direct mode for synthetic timers

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Message-ID: <20181203171220.GA2886@rkaganb.sw.ru>
Date:   Mon, 3 Dec 2018 17:12:24 +0000
From:   Roman Kagan <rkagan@...tuozzo.com>
To:     Vitaly Kuznetsov <vkuznets@...hat.com>
CC:     "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "K. Y. Srinivasan" <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        "x86@...nel.org" <x86@...nel.org>,
        "Michael Kelley (EOSG)" <Michael.H.Kelley@...rosoft.com>
Subject: Re: [PATCH v2 3/4] x86/kvm/hyper-v: direct mode for synthetic timers

On Mon, Nov 26, 2018 at 04:47:31PM +0100, Vitaly Kuznetsov wrote:
> @@ -379,6 +398,14 @@ void kvm_hv_synic_send_eoi(struct kvm_vcpu *vcpu, int vector)
>  	for (i = 0; i < ARRAY_SIZE(synic->sint); i++)
>  		if (synic_get_sint_vector(synic_read_sint(synic, i)) == vector)
>  			kvm_hv_notify_acked_sint(vcpu, i);
> +
> +	for (i = 0; i < ARRAY_SIZE(hv_vcpu->stimer); i++) {
> +		stimer = &hv_vcpu->stimer[i];
> +		if (stimer->msg_pending && stimer->config.enable &&
> +		    stimer->config.direct_mode &&
> +		    stimer->config.apic_vector == vector)
> +			stimer_mark_pending(stimer, false);
> +	}
>  }

While debugging another issue with synic timers, it just occurred to me
that with direct timers no extra processing is necessary on EOI: unlike
traditional synic timers which may have failed to deliver a message and
want to be notified when they can retry, direct timers just set the irq
directly in the apic.

So this hunk shouldn't be needed, should it?

Roman.