linux-kernel - Re: [PATCH RFC v7 01/64] KVM: Fix memslot boundary condition for large page

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Message-ID: <20230105033700.GB2251521@chaop.bj.intel.com>
Date:   Thu, 5 Jan 2023 11:37:00 +0800
From:   Chao Peng <chao.p.peng@...ux.intel.com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     Michael Roth <michael.roth@....com>, kvm@...r.kernel.org,
        linux-coco@...ts.linux.dev, linux-mm@...ck.org,
        linux-crypto@...r.kernel.org, x86@...nel.org,
        linux-kernel@...r.kernel.org, tglx@...utronix.de, mingo@...hat.com,
        jroedel@...e.de, thomas.lendacky@....com, hpa@...or.com,
        ardb@...nel.org, pbonzini@...hat.com, seanjc@...gle.com,
        vkuznets@...hat.com, wanpengli@...cent.com, jmattson@...gle.com,
        luto@...nel.org, dave.hansen@...ux.intel.com, slp@...hat.com,
        pgonda@...gle.com, peterz@...radead.org,
        srinivas.pandruvada@...ux.intel.com, rientjes@...gle.com,
        dovmurik@...ux.ibm.com, tobin@....com, vbabka@...e.cz,
        kirill@...temov.name, ak@...ux.intel.com, tony.luck@...el.com,
        marcorr@...gle.com, sathyanarayanan.kuppuswamy@...ux.intel.com,
        alpergun@...gle.com, dgilbert@...hat.com, jarkko@...nel.org,
        ashish.kalra@....com, harald@...fian.com,
        Nikunj A Dadhania <nikunj@....com>
Subject: Re: [PATCH RFC v7 01/64] KVM: Fix memslot boundary condition for
 large page

On Thu, Dec 22, 2022 at 01:16:04PM +0100, Borislav Petkov wrote:
> On Wed, Dec 14, 2022 at 01:39:53PM -0600, Michael Roth wrote:
> > From: Nikunj A Dadhania <nikunj@....com>
> > 
> > Aligned end boundary causes a kvm crash, handle the case.
> > 
> > Signed-off-by: Nikunj A Dadhania <nikunj@....com>
> > Signed-off-by: Michael Roth <michael.roth@....com>
> > ---
> >  arch/x86/kvm/mmu/mmu.c | 3 +++
> >  1 file changed, 3 insertions(+)
> > 
> > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> > index b1953ebc012e..b3ffc61c668c 100644
> > --- a/arch/x86/kvm/mmu/mmu.c
> > +++ b/arch/x86/kvm/mmu/mmu.c
> > @@ -7159,6 +7159,9 @@ static void kvm_update_lpage_private_shared_mixed(struct kvm *kvm,
> >  		for (gfn = first + pages; gfn < last; gfn += pages)
> >  			linfo_set_mixed(gfn, slot, level, false);
> >  
> > +		if (gfn == last)
> > +			goto out;
> 
> I'm guessing this was supposed to be "return;" here:

If we finally need this, this should be "continue;", we can't skip the
remaining huge page levels.

Thanks,
Chao
> 
> arch/x86/kvm/mmu/mmu.c: In function ‘kvm_update_lpage_private_shared_mixed’:
> arch/x86/kvm/mmu/mmu.c:7090:25: error: label ‘out’ used but not defined
>  7090 |                         goto out;
>       |                         ^~~~
> 
> /me goes and digs deeper.
> 
> Aha, it was a "return" but you reordered the patches and the one adding
> the out label:
> 
> KVM: x86: Add 'update_mem_attr' x86 op
> 
> went further down and this became the first but it didn't have the label
> anymore.
> 
> Yeah, each patch needs to build successfully for bisection reasons, ofc.
> 
> Thx.
> 
> -- 
> Regards/Gruss,
>     Boris.
> 
> https://people.kernel.org/tglx/notes-about-netiquette