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From: Vishal Annapurve <vannapurve@google.com>
To: Xiaoyao Li <xiaoyao.li@intel.com>
Cc: Sean Christopherson <seanjc@google.com>,
	Michael Roth <michael.roth@amd.com>,
	Chao Peng <chao.p.peng@linux.intel.com>,
	"Nikunj A. Dadhania" <nikunj@amd.com>,
	kvm list <kvm@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
	linux-api@vger.kernel.org, linux-doc@vger.kernel.org,
	qemu-devel@nongnu.org, Paolo Bonzini <pbonzini@redhat.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	x86 <x86@kernel.org>, "H . Peter Anvin" <hpa@zytor.com>,
	Hugh Dickins <hughd@google.com>, Jeff Layton <jlayton@kernel.org>,
	"J . Bruce Fields" <bfields@fieldses.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Mike Rapoport <rppt@kernel.org>,
	Steven Price <steven.price@arm.com>,
	"Maciej S . Szmigiero" <mail@maciej.szmigiero.name>,
	Vlastimil Babka <vbabka@suse.cz>,
	Yu Zhang <yu.c.zhang@linux.intel.com>,
	"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
	Andy Lutomirski <luto@kernel.org>,
	Jun Nakajima <jun.nakajima@intel.com>,
	Dave Hansen <dave.hansen@intel.com>,
	Andi Kleen <ak@linux.intel.com>,
	David Hildenbrand <david@redhat.com>,
	aarcange@redhat.com, ddutile@redhat.com, dhildenb@redhat.com,
	Quentin Perret <qperret@google.com>,
	mhocko@suse.com
Subject: Re: [PATCH v6 6/8] KVM: Handle page fault for private memory
Date: Wed, 20 Jul 2022 16:08:10 -0700	[thread overview]
Message-ID: <CAGtprH9knCr++C7jgXYCi1zfYcreip1uun-d+eucjEQy9xymNg@mail.gmail.com> (raw)
In-Reply-To: <5d0b9341-78b5-0959-2517-0fb1fe83a205@intel.com>

> > Hmm, so a new slot->arch.page_attr array shouldn't be necessary, KVM can instead
> > update slot->arch.lpage_info on shared<->private conversions.  Detecting whether
> > a given range is partially mapped could get nasty if KVM defers tracking to the
> > backing store, but if KVM itself does the tracking as was previously suggested[*],
> > then updating lpage_info should be relatively straightfoward, e.g. use
> > xa_for_each_range() to see if a given 2mb/1gb range is completely covered (fully
> > shared) or not covered at all (fully private).
> >
> > [*] https://lore.kernel.org/all/YofeZps9YXgtP3f1@google.com
>
> Yes, slot->arch.page_attr was introduced to help identify whether a page
> is completely shared/private at given level. It seems XARRAY can serve
> the same purpose, though I know nothing about it. Looking forward to
> seeing the patch of using XARRAY.
>
> yes, update slot->arch.lpage_info is good to utilize the existing logic
> and Isaku has applied it to slot->arch.lpage_info for 2MB support patches.

Chao, are you planning to implement these changes to ensure proper
handling of hugepages partially mapped as private/shared in subsequent
versions of this series?
Or is this something left to be handled by the architecture specific code?

Regards,
Vishal

  reply	other threads:[~2022-07-20 23:09 UTC|newest]

Thread overview: 58+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-05-19 15:37 [PATCH v6 0/8] KVM: mm: fd-based approach for supporting KVM guest private memory Chao Peng
2022-05-19 15:37 ` [PATCH v6 1/8] mm: Introduce memfile_notifier Chao Peng
2022-05-19 15:37 ` [PATCH v6 2/8] mm/shmem: Support memfile_notifier Chao Peng
2022-05-19 15:37 ` [PATCH v6 3/8] mm/memfd: Introduce MFD_INACCESSIBLE flag Chao Peng
2022-05-31 19:15   ` Vishal Annapurve
2022-06-01 10:17     ` Chao Peng
2022-06-01 12:11       ` Gupta, Pankaj
2022-06-02 10:07         ` Chao Peng
2022-06-14 20:23           ` Sean Christopherson
2022-06-15  8:53             ` Chao Peng
2022-05-19 15:37 ` [PATCH v6 4/8] KVM: Extend the memslot to support fd-based private memory Chao Peng
2022-05-20 17:57   ` Andy Lutomirski
2022-05-20 18:31     ` Sean Christopherson
2022-05-22  4:03       ` Andy Lutomirski
2022-05-23 13:21       ` Chao Peng
2022-05-23 15:22         ` Sean Christopherson
2022-05-30 13:26           ` Chao Peng
2022-06-10 16:14             ` Sean Christopherson
2022-06-14  6:45               ` Chao Peng
2022-06-23 22:59       ` Michael Roth
2022-06-24  8:54         ` Chao Peng
2022-06-24 13:01           ` Michael Roth
2022-06-17 20:52   ` Sean Christopherson
2022-06-17 21:27     ` Sean Christopherson
2022-06-20 14:09       ` Chao Peng
2022-06-20 14:08     ` Chao Peng
2022-05-19 15:37 ` [PATCH v6 5/8] KVM: Add KVM_EXIT_MEMORY_FAULT exit Chao Peng
2022-05-19 15:37 ` [PATCH v6 6/8] KVM: Handle page fault for private memory Chao Peng
2022-06-17 21:30   ` Sean Christopherson
2022-06-20 14:16     ` Chao Peng
2022-08-19  0:40     ` Kirill A. Shutemov
2022-08-25 23:43       ` Sean Christopherson
2022-06-24  3:58   ` Nikunj A. Dadhania
2022-06-24  9:02     ` Chao Peng
2022-06-30 19:14       ` Vishal Annapurve
2022-06-30 22:21         ` Michael Roth
2022-07-01  1:21           ` Xiaoyao Li
2022-07-07 20:08             ` Sean Christopherson
2022-07-08  3:29               ` Xiaoyao Li
2022-07-20 23:08                 ` Vishal Annapurve [this message]
2022-07-21  9:45                   ` Chao Peng
2022-05-19 15:37 ` [PATCH v6 7/8] KVM: Enable and expose KVM_MEM_PRIVATE Chao Peng
2022-06-23 22:07   ` Michael Roth
2022-06-24  8:43     ` Chao Peng
2022-05-19 15:37 ` [PATCH v6 8/8] memfd_create.2: Describe MFD_INACCESSIBLE flag Chao Peng
2022-06-06 20:09 ` [PATCH v6 0/8] KVM: mm: fd-based approach for supporting KVM guest private memory Vishal Annapurve
2022-06-07  6:57   ` Chao Peng
2022-06-08  0:55     ` Marc Orr
2022-06-08  2:18       ` Chao Peng
2022-06-08 19:37         ` Vishal Annapurve
2022-06-09 20:29           ` Sean Christopherson
2022-06-14  7:28             ` Chao Peng
2022-06-14 17:37               ` Andy Lutomirski
2022-06-14 19:08                 ` Sean Christopherson
2022-06-14 20:59                   ` Andy Lutomirski
2022-06-15  9:17                     ` Chao Peng
2022-06-15 14:29                       ` Sean Christopherson
2022-06-10  0:11         ` Marc Orr

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