linux-kernel - Re: [RFCv2 09/16] KVM: mm: Introduce VM_KVM

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Date:   Thu, 22 Oct 2020 15:01:42 +0300
From:   "Kirill A. Shutemov" <kirill@...temov.name>
To:     "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>
Cc:     "peterz@...radead.org" <peterz@...radead.org>,
        "jmattson@...gle.com" <jmattson@...gle.com>,
        "Christopherson, Sean J" <sean.j.christopherson@...el.com>,
        "vkuznets@...hat.com" <vkuznets@...hat.com>,
        "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
        "joro@...tes.org" <joro@...tes.org>,
        "luto@...nel.org" <luto@...nel.org>,
        "pbonzini@...hat.com" <pbonzini@...hat.com>,
        "wanpengli@...cent.com" <wanpengli@...cent.com>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kirill.shutemov@...ux.intel.com" <kirill.shutemov@...ux.intel.com>,
        "keescook@...omium.org" <keescook@...omium.org>,
        "rppt@...nel.org" <rppt@...nel.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "x86@...nel.org" <x86@...nel.org>,
        "aarcange@...hat.com" <aarcange@...hat.com>,
        "liran.alon@...cle.com" <liran.alon@...cle.com>,
        "wad@...omium.org" <wad@...omium.org>,
        "rientjes@...gle.com" <rientjes@...gle.com>,
        "Kleen, Andi" <andi.kleen@...el.com>
Subject: Re: [RFCv2 09/16] KVM: mm: Introduce VM_KVM_PROTECTED

On Wed, Oct 21, 2020 at 06:47:32PM +0000, Edgecombe, Rick P wrote:
> On Tue, 2020-10-20 at 09:18 +0300, Kirill A. Shutemov wrote:
> >  include/linux/mm.h  |  8 ++++++++
> >  mm/gup.c            | 20 ++++++++++++++++----
> >  mm/huge_memory.c    | 20 ++++++++++++++++----
> >  mm/memory.c         |  3 +++
> >  mm/mmap.c           |  3 +++
> >  virt/kvm/async_pf.c |  2 +-
> >  virt/kvm/kvm_main.c |  9 +++++----
> >  7 files changed, 52 insertions(+), 13 deletions(-)
> 
> There is another get_user_pages() in
> paging_tmpl.h:FNAME(cmpxchg_gpte). 

Right, I will look into it. I wounder why I don't step onto it.

> Also, did you leave off FOLL_KVM in gfn_to_page_many_atomic() on
> purpose? It looks like its only used for pte prefetch which I guess is
> not required.

FOLL_FAST_ONLY is going to fail anyway. The caller has to handle it
gracefully.

-- 
 Kirill A. Shutemov