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From: "Jan Beulich" <JBeulich@suse.com>
To: Paul Durrant <paul.durrant@citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>, KeirFraser <keir@xen.org>,
	Stefano Stabellini <stefano.stabellini@eu.citrix.com>,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	Ian Jackson <ian.jackson@eu.citrix.com>,
	xen-devel@lists.xenproject.org
Subject: Re: [PATCH v6] x86/hvm/viridian: Enable APIC assist enlightenment
Date: Thu, 24 Mar 2016 07:50:59 -0600	[thread overview]
Message-ID: <56F3FED302000078000E0227@prv-mh.provo.novell.com> (raw)
In-Reply-To: <1458297150-1574-1-git-send-email-paul.durrant@citrix.com>

>>> On 18.03.16 at 11:32, <paul.durrant@citrix.com> wrote:
> @@ -278,6 +281,53 @@ static void teardown_apic_assist(struct vcpu *v)
>      put_page_and_type(page);
>  }
>  
> +void viridian_start_apic_assist(struct vcpu *v, int vector)
> +{
> +    uint32_t *va = v->arch.hvm_vcpu.viridian.apic_assist.va;
> +
> +    if ( !va )
> +        return;
> +
> +    /*
> +     * If there is already an assist pending then something has gone
> +     * wrong and the VM will most likely hang so force a crash now
> +     * to make the problem clear.
> +     */
> +    if ( v->arch.hvm_vcpu.viridian.apic_assist.vector >= 0 )
> +        domain_crash(v->domain);
> +
> +    v->arch.hvm_vcpu.viridian.apic_assist.vector = vector;

Considering the osstest failures I (see also IRC) I now wonder
what happens if the guest gets migrated while a vCPU has this
field holding a valid vector, namely how ...

> @@ -1170,10 +1183,27 @@ int vlapic_has_pending_irq(struct vcpu *v)
>           !nestedhvm_vcpu_in_guestmode(v) )
>          return irr;
>  
> +    /*
> +     * If APIC assist was used then there may have been no EOI so
> +     * we need to clear the requisite bit from the ISR here, before
> +     * comparing with the IRR.
> +     */
> +    vector = viridian_complete_apic_assist(v);
> +    if ( vector != -1 )
> +        vlapic_clear_vector(vector, &vlapic->regs->data[APIC_ISR]);

... this would then be taken care of on the new host.

Jan


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  parent reply	other threads:[~2016-03-24 13:51 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-03-18 10:32 Paul Durrant
2016-03-18 11:05 ` Jan Beulich
2016-03-18 12:30 ` Wei Liu
2016-03-24 13:50 ` Jan Beulich [this message]
2016-03-24 13:56   ` Paul Durrant

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