linux-kernel - Re: [PATCH v2 1/3] KVM: x86: move kvm_vcpu_gfn_to_memslot() out of try_async

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Message-ID: <20200904034714.GA22394@sjchrist-ice>
Date:   Thu, 3 Sep 2020 20:47:16 -0700
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Vitaly Kuznetsov <vkuznets@...hat.com>
Cc:     kvm@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Peter Xu <peterx@...hat.com>, Michael Tsirkin <mst@...hat.com>,
        Julia Suvorova <jsuvorov@...hat.com>,
        Andy Lutomirski <luto@...nel.org>,
        Andrew Jones <drjones@...hat.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/3] KVM: x86: move kvm_vcpu_gfn_to_memslot() out of
 try_async_pf()

On Tue, Sep 01, 2020 at 04:15:07PM +0200, Vitaly Kuznetsov wrote:
> Sean Christopherson <sean.j.christopherson@...el.com> writes:
> 
> > On Fri, Aug 07, 2020 at 04:12:30PM +0200, Vitaly Kuznetsov wrote:
> >> No functional change intended. Slot flags will need to be analyzed
> >> prior to try_async_pf() when KVM_MEM_PCI_HOLE is implemented.
> >
> 
> (Sorry it took me so long to reply. No, I wasn't hoping for Paolo's
> magical "queued, thanks", I just tried to not read my email while on
> vacation).
> 
> > Why?  Wouldn't it be just as easy, and arguably more appropriate, to add
> > KVM_PFN_ERR_PCI_HOLE and update handle_abornmal_pfn() accordinaly?
> >
> 
> Yes, we can do that, but what I don't quite like here is that
> try_async_pf() does much more than 'trying async PF'. In particular, it
> extracts 'pfn' and this is far from being obvious. Maybe we can rename
> try_async_pf() somewhat smartly (e.g. 'try_handle_pf()')? Your
> suggestion will make perfect sense to me then.

Ya, try_async_pf() is a horrible name.  try_handle_pf() isn't bad, but it's
not technically handling the fault.  Maybe try_get_pfn() with an inverted
return?

	if (!try_get_pfn(...))
		return RET_PF_RETRY;