linux-kernel - Re: [PATCHv4 3/5] kvm: host side for eoi optimization

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20120517072841.GW32036@redhat.com>
Date:	Thu, 17 May 2012 10:28:41 +0300
From:	Gleb Natapov <gleb@...hat.com>
To:	"Michael S. Tsirkin" <mst@...hat.com>
Cc:	Marcelo Tosatti <mtosatti@...hat.com>, x86@...nel.org,
	kvm@...r.kernel.org, Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, Avi Kivity <avi@...hat.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCHv4 3/5] kvm: host side for eoi optimization

On Wed, May 16, 2012 at 10:07:58PM +0300, Michael S. Tsirkin wrote:
> > This code is reached from kvm_cpu_get_interrupt(), but this function will
> > not be called in above scenario.
> 
> I think I see. So this shall fix it also makes code cleaner
> (no -2 hack). Right? kvm_apic_has_interrupt is called correct?
> 
> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> index b4f7013..5a38e34 100644
> --- a/arch/x86/kvm/lapic.c
> +++ b/arch/x86/kvm/lapic.c
> @@ -1273,8 +1273,12 @@ int kvm_apic_has_interrupt(struct kvm_vcpu *vcpu)
>  	highest_irr = apic_find_highest_irr(apic);
>  	if (highest_irr == -1)
>  		return -1;
> -	if (((highest_irr & 0xF0) <= apic_get_reg(apic, APIC_PROCPRI)))
> -		return -2;
> +	/* Detect interrupt nesting and disable EOI optimization */
> +	if ((highest_irr & 0xF0) <= apic_get_reg(apic, APIC_PROCPRI)) {
> +		if (pv_eoi_enabled(vcpu))
> +			pv_eoi_clr_pending(vcpu);
> +		return -1;
> +	}
>  	return highest_irr;
>  }
>  
I do not like it. kvm_apic_has_interrupt() does not suppose to mutate
state.

> @@ -1306,10 +1310,6 @@ int kvm_get_apic_interrupt(struct kvm_vcpu *vcpu)
>  	int vector = kvm_apic_has_interrupt(vcpu);
>  	struct kvm_lapic *apic = vcpu->arch.apic;
>  
> -	/* Detect interrupt nesting and disable EOI optimization */
> -	if (pv_eoi_enabled(vcpu) && vector == -2)
> -		pv_eoi_clr_pending(vcpu);
> -
>  	if (vector < 0)
>  		return -1;
>  

--
			Gleb.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/