From: "Jan Beulich" <JBeulich@suse.com>
To: Chao Gao <chao.gao@intel.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>, xen-devel@lists.xen.org
Subject: Re: [PATCH v2] x86/vlapic: Don't reset APIC ID when handling INIT signal
Date: Wed, 19 Apr 2017 08:17:14 -0600 [thread overview]
Message-ID: <58F78D8A0200007800151FE6@prv-mh.provo.novell.com> (raw)
In-Reply-To: <1492584052-92224-1-git-send-email-chao.gao@intel.com>
>>> On 19.04.17 at 08:40, <chao.gao@intel.com> wrote:
> @@ -1257,7 +1257,12 @@ void vlapic_reset(struct vlapic *vlapic)
> }
> vlapic_set_reg(vlapic, APIC_ICR, 0);
> vlapic_set_reg(vlapic, APIC_ICR2, 0);
> - vlapic_set_reg(vlapic, APIC_LDR, 0);
> + /*
> + * LDR is read-only in x2APIC mode. Preserve its value when handling
> + * INIT signal in x2APIC mode.
> + */
> + if ( !vlapic_x2apic_mode(vlapic) )
In order for this to work you need to ...
> + vlapic_set_reg(vlapic, APIC_LDR, 0);
> vlapic_set_reg(vlapic, APIC_TASKPRI, 0);
> vlapic_set_reg(vlapic, APIC_TMICT, 0);
> vlapic_set_reg(vlapic, APIC_TMCCT, 0);
> @@ -1275,6 +1280,22 @@ void vlapic_reset(struct vlapic *vlapic)
> destroy_periodic_time(&vlapic->pt);
> }
>
> +/* Reset the VLAPIC back to its power-on/reset state. */
> +void vlapic_reset(struct vlapic *vlapic)
> +{
> + const struct vcpu *v = vlapic_vcpu(vlapic);
> +
> + if ( !has_vlapic(v->domain) )
> + return;
> +
> + vlapic_set_reg(vlapic, APIC_ID, (v->vcpu_id * 2) << 24);
> + vlapic_set_reg(vlapic, APIC_LDR, 0);
> + vlapic_do_init(vlapic);
> +
> + vlapic->hw.apic_base_msr &= ~(uint64_t)MSR_IA32_APICBASE_EXTD;
... do this before calling vlapic_do_init() afaict (and I see no strong
reason why you would need a cast here)). Likely it is a good idea
then to also ...
> + vlapic->hw.apic_base_msr |= MSR_IA32_APICBASE_ENABLE;
... do this up front.
> @@ -1489,8 +1510,7 @@ int vlapic_init(struct vcpu *v)
>
> vlapic_reset(vlapic);
>
> - vlapic->hw.apic_base_msr = (MSR_IA32_APICBASE_ENABLE |
> - APIC_DEFAULT_PHYS_BASE);
> + vlapic->hw.apic_base_msr |= APIC_DEFAULT_PHYS_BASE;
Perhaps better move this ahead of the call to vlapic_reset() then
too.
Remains the question (not answered by the SDM afaics): What
happens to the base address during reset?
Jan
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next prev parent reply other threads:[~2017-04-19 14:17 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-19 6:40 [PATCH v2] x86/vlapic: Don't reset APIC ID when handling INIT signal Chao Gao
2017-04-19 14:17 ` Jan Beulich [this message]
2017-04-19 7:41 ` Chao Gao
2017-04-19 15:04 ` Jan Beulich
2017-04-19 19:33 ` Chao Gao
2017-04-20 9:55 ` Jan Beulich
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