Re: [PATCH] KVM: x86: Do not change ICR on write to APIC_SELF_IPI

[Andrew Cooper]

> On Thu, Feb 24, 2022, Paolo Bonzini wrote:
>> Emulating writes to SELF_IPI with a write to ICR has an unwanted side
>> effect: the value of ICR in vAPIC page gets changed. The lists
>> SELF_IPI as write-only,                                                  ^
>> 					         |- SDM
>>
>> with no associated MMIO offset, so any write should have no visible
>> side effect in the vAPIC page. Reported-by: Chao Gao
>> <chao.gao@xxxxxxxxx> Signed-off-by: Paolo Bonzini
>> <pbonzini@xxxxxxxxxx> ---
>
> Reviewed-by: Sean Christopherson <seanjc@xxxxxxxxxx>

This patch was just attempted to be ported to Xen.

Contrary to the claim, Intel Core (P-cores) really do overwrite ICR when
processing SELF_IPI.

~Andrew