Re: [Xen-devel] [PATCH v3] x86/vlapic: Don't reset APIC ID when handling INIT signal

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 19.04.17 at 22:22, <chao.gao@xxxxxxxxx> wrote:
> According to SDM "ADVANCED PROGRAMMABLE INTERRUPT CONTROLLER (APIC) ->
> "EXTENDED XAPIC (X2APIC)" -> "x2APIC State Transitions", the APIC mode
> and APIC ID are preserved when handling INIT signal and a reset places
> APIC to xAPIC mode and APIC base address to 0xFEE00000h (this part
> is in "Local APIC" -> "Local APIC Status and Location"). So there are
> two problems in current code:
> 1. Using reset logic (aka vlapic_reset) to handle INIT signal.
> 2. Forgetting resetting APIC mode and base address in vlapic_reset()
> 
> This patch introduces a new function vlapic_do_init() and replaces the
> wrongly used vlapic_reset(). Also reset APIC mode and APIC base address
> in vlapic_reset().
> 
> Note that: LDR is read only in x2APIC mode. Resetting it to zero in x2APIC
> mode is unreasonable. This patch also doesn't reset LDR when handling INIT
> signal in x2APIC mode.
> 
> Signed-off-by: Chao Gao <chao.gao@xxxxxxxxx>

Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>

> I regard this patch as a bug fix. But I haven't seen issues caused by
> this bug and am not sure of the existance of such issues. Anyhow Cc
> Julien and leave the decision to you (Julien and Jan).

Julien,

I'm slightly in favor of taking it now, but I won't object if you decide
otherwise.

Jan


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