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From: Peter Xu <peterx@redhat.com>
To: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
	Nitesh Narayan Lal <nitesh@redhat.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>
Subject: Re: [PATCH v4 3/6] KVM: X86: Use APIC_DEST_* macros properly in kvm_lapic_irq.dest_mode
Date: Wed, 4 Dec 2019 13:48:44 -0500
Message-ID: <20191204184844.GA19939@xz-x1> (raw)
In-Reply-To: <20191203222036.GL19877@linux.intel.com>

On Tue, Dec 03, 2019 at 02:20:36PM -0800, Sean Christopherson wrote:
> On Tue, Dec 03, 2019 at 05:15:19PM -0500, Peter Xu wrote:
> > On Tue, Dec 03, 2019 at 02:07:52PM -0800, Sean Christopherson wrote:
> > > On Tue, Dec 03, 2019 at 11:59:00AM -0500, Peter Xu wrote:
> > > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> > > > index b79cd6aa4075..f815c97b1b57 100644
> > > > --- a/arch/x86/include/asm/kvm_host.h
> > > > +++ b/arch/x86/include/asm/kvm_host.h
> > > > @@ -1022,6 +1022,11 @@ struct kvm_lapic_irq {
> > > >  	bool msi_redir_hint;
> > > >  };
> > > >  
> > > > +static inline u16 kvm_lapic_irq_dest_mode(bool dest_mode)
> > > > +{
> > > > +	return dest_mode ? APIC_DEST_LOGICAL : APIC_DEST_PHYSICAL;
> > > 
> > > IMO this belongs in ioapic.c as it's specifically provided for converting
> > > an I/O APIC redirection entry into a local APIC destination mode.  Without
> > > the I/O APIC context, %true==APIC_DEST_LOGICAL looks like a completely
> > > arbitrary decision.  And if it's in ioapic.c, it can take the union
> > > of a bool, which avoids the casting and shortens the callers.  E.g.:
> > > 
> > > static u64 ioapic_to_lapic_dest_mode(union kvm_ioapic_redirect_entry *e)
> > > {
> > > 	return e->fields.dest_mode ?  APIC_DEST_LOGICAL : APIC_DEST_PHYSICAL;
> > > }
> > > 
> > > The other option would be to use the same approach as delivery_mode and
> > > open code the shift.
> > 
> > It's also used for MSI address encodings, please see below [1].
> 
> Boooh.  How about naming the param "logical_dest_mode" or something else
> with "logical" in the name so that the correctness of the function itself
> is apparent?

Ok, will do.  Thanks,

-- 
Peter Xu


  reply index

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-03 16:58 [PATCH v4 0/6] KVM: X86: Cleanups on dest_mode and headers Peter Xu
2019-12-03 16:58 ` [PATCH v4 1/6] KVM: X86: Fix kvm_bitmap_or_dest_vcpus() to use irq shorthand Peter Xu
2019-12-03 16:58 ` [PATCH v4 2/6] KVM: X86: Move irrelevant declarations out of ioapic.h Peter Xu
2019-12-03 16:59 ` [PATCH v4 3/6] KVM: X86: Use APIC_DEST_* macros properly in kvm_lapic_irq.dest_mode Peter Xu
2019-12-03 22:07   ` Sean Christopherson
2019-12-03 22:15     ` Peter Xu
2019-12-03 22:20       ` Sean Christopherson
2019-12-04 18:48         ` Peter Xu [this message]
2019-12-03 16:59 ` [PATCH v4 4/6] KVM: X86: Drop KVM_APIC_SHORT_MASK and KVM_APIC_DEST_MASK Peter Xu
2019-12-03 16:59 ` [PATCH v4 5/6] KVM: X86: Fix callers of kvm_apic_match_dest() to use correct macros Peter Xu
2019-12-03 16:59 ` [PATCH v4 6/6] KVM: X86: Conert the last users of "shorthand = 0" to use macros Peter Xu
2019-12-04 16:12   ` Vitaly Kuznetsov
2019-12-04 18:53     ` Peter Xu

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