linux-kernel - Re: [PATCH 4.19 08/57] KVM: x86: Fix split-irqchip vs interrupt injection window request

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Message-ID: <20201201153337.GA23661@amd>
Date:   Tue, 1 Dec 2020 16:33:37 +0100
From:   Pavel Machek <pavel@...x.de>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        David Woodhouse <dwmw@...zon.co.uk>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Nikos Tsironis <ntsironis@...ikto.com>
Subject: Re: [PATCH 4.19 08/57] KVM: x86: Fix split-irqchip vs interrupt
 injection window request

Hi!

> - in order to tell userspace we will inject its interrupt ("IRQ
>   window open" i.e. kvm_vcpu_ready_for_interrupt_injection), both
>   KVM and the vCPU need to be ready to accept the interrupt.
> 
> ... and this is what the patch implements.
> 
> Reported-by: David Woodhouse <dwmw@...zon.co.uk>
> Analyzed-by: David Woodhouse <dwmw@...zon.co.uk>
> Cc: stable@...r.kernel.org

This makes no difference for -stable, but the patch is confused about
types:

> +++ b/arch/x86/kvm/x86.c
> @@ -3351,21 +3351,23 @@ static int kvm_vcpu_ioctl_set_lapic(stru
>  
>  static int kvm_cpu_accept_dm_intr(struct kvm_vcpu *vcpu)
>  {
> +	/*
> +	 * We can accept userspace's request for interrupt injection
> +	 * as long as we have a place to store the interrupt number.
> +	 * The actual injection will happen when the CPU is able to
> +	 * deliver the interrupt.
> +	 */
> +	if (kvm_cpu_has_extint(vcpu))
> +		return false;

Since function is "static int" it should probably return 0.

Best regards,
								Pavel
--
DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany

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