From: Chao Peng <chao.p.peng@linux.intel.com>
To: Vishal Annapurve <vannapurve@google.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
linux-api@vger.kernel.org, qemu-devel@nongnu.org,
Paolo Bonzini <pbonzini@redhat.com>,
Jonathan Corbet <corbet@lwn.net>,
Sean Christopherson <seanjc@google.com>,
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@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@intel.com, ak@linux.intel.com, david@redhat.com
Subject: Re: [PATCH v5 11/13] KVM: Zap existing KVM mappings when pages changed in the private fd
Date: Wed, 20 Apr 2022 11:17:18 +0800 [thread overview]
Message-ID: <20220420031718.GA39591@chaop.bj.intel.com> (raw)
In-Reply-To: <CAGtprH-qTB2sehidF7xkSvR3X4D5cUOLpMBXf4mhTEh0BUR-mQ@mail.gmail.com>
On Tue, Apr 19, 2022 at 03:43:56PM -0700, Vishal Annapurve wrote:
> On Thu, Mar 10, 2022 at 6:11 AM Chao Peng <chao.p.peng@linux.intel.com> wrote:
> >
> > KVM gets notified when memory pages changed in the memory backing store.
> > When userspace allocates the memory with fallocate() or frees memory
> > with fallocate(FALLOC_FL_PUNCH_HOLE), memory backing store calls into
> > KVM fallocate/invalidate callbacks respectively. To ensure KVM never
> > maps both the private and shared variants of a GPA into the guest, in
> > the fallocate callback, we should zap the existing shared mapping and
> > in the invalidate callback we should zap the existing private mapping.
> >
> > In the callbacks, KVM firstly converts the offset range into the
> > gfn_range and then calls existing kvm_unmap_gfn_range() which will zap
> > the shared or private mapping. Both callbacks pass in a memslot
> > reference but we need 'kvm' so add a reference in memslot structure.
> >
> > Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>
> > Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com>
> > ---
> > include/linux/kvm_host.h | 3 ++-
> > virt/kvm/kvm_main.c | 36 ++++++++++++++++++++++++++++++++++++
> > 2 files changed, 38 insertions(+), 1 deletion(-)
> >
> > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> > index 9b175aeca63f..186b9b981a65 100644
> > --- a/include/linux/kvm_host.h
> > +++ b/include/linux/kvm_host.h
> > @@ -236,7 +236,7 @@ bool kvm_setup_async_pf(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
> > int kvm_async_pf_wakeup_all(struct kvm_vcpu *vcpu);
> > #endif
> >
> > -#ifdef KVM_ARCH_WANT_MMU_NOTIFIER
> > +#if defined(KVM_ARCH_WANT_MMU_NOTIFIER) || defined(CONFIG_MEMFILE_NOTIFIER)
> > struct kvm_gfn_range {
> > struct kvm_memory_slot *slot;
> > gfn_t start;
> > @@ -568,6 +568,7 @@ struct kvm_memory_slot {
> > loff_t private_offset;
> > struct memfile_pfn_ops *pfn_ops;
> > struct memfile_notifier notifier;
> > + struct kvm *kvm;
> > };
> >
> > static inline bool kvm_slot_is_private(const struct kvm_memory_slot *slot)
> > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> > index 67349421eae3..52319f49d58a 100644
> > --- a/virt/kvm/kvm_main.c
> > +++ b/virt/kvm/kvm_main.c
> > @@ -841,8 +841,43 @@ static int kvm_init_mmu_notifier(struct kvm *kvm)
> > #endif /* CONFIG_MMU_NOTIFIER && KVM_ARCH_WANT_MMU_NOTIFIER */
> >
> > #ifdef CONFIG_MEMFILE_NOTIFIER
> > +static void kvm_memfile_notifier_handler(struct memfile_notifier *notifier,
> > + pgoff_t start, pgoff_t end)
> > +{
> > + int idx;
> > + struct kvm_memory_slot *slot = container_of(notifier,
> > + struct kvm_memory_slot,
> > + notifier);
> > + struct kvm_gfn_range gfn_range = {
> > + .slot = slot,
> > + .start = start - (slot->private_offset >> PAGE_SHIFT),
> > + .end = end - (slot->private_offset >> PAGE_SHIFT),
> > + .may_block = true,
> > + };
> > + struct kvm *kvm = slot->kvm;
> > +
> > + gfn_range.start = max(gfn_range.start, slot->base_gfn);
>
> gfn_range.start seems to be page offset within the file. Should this rather be:
> gfn_range.start = slot->base_gfn + min(gfn_range.start, slot->npages);
Right. For start we don't really need care about the uppper bound
here (will check below), so this should be enough:
gfn_range.start = slot->base_gfn + gfn_range.start;
>
> > + gfn_range.end = min(gfn_range.end, slot->base_gfn + slot->npages);
> > +
>
> Similar to previous comment, should this rather be:
> gfn_range.end = slot->base_gfn + min(gfn_range.end, slot->npages);
This is correct.
Thanks,
Chao
>
> > + if (gfn_range.start >= gfn_range.end)
> > + return;
> > +
> > + idx = srcu_read_lock(&kvm->srcu);
> > + KVM_MMU_LOCK(kvm);
> > + kvm_unmap_gfn_range(kvm, &gfn_range);
> > + kvm_flush_remote_tlbs(kvm);
> > + KVM_MMU_UNLOCK(kvm);
> > + srcu_read_unlock(&kvm->srcu, idx);
> > +}
> > +
> > +static struct memfile_notifier_ops kvm_memfile_notifier_ops = {
> > + .invalidate = kvm_memfile_notifier_handler,
> > + .fallocate = kvm_memfile_notifier_handler,
> > +};
> > +
> > static inline int kvm_memfile_register(struct kvm_memory_slot *slot)
> > {
> > + slot->notifier.ops = &kvm_memfile_notifier_ops;
> > return memfile_register_notifier(file_inode(slot->private_file),
> > &slot->notifier,
> > &slot->pfn_ops);
> > @@ -1963,6 +1998,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
> > new->private_file = file;
> > new->private_offset = mem->flags & KVM_MEM_PRIVATE ?
> > region_ext->private_offset : 0;
> > + new->kvm = kvm;
> >
> > r = kvm_set_memslot(kvm, old, new, change);
> > if (!r)
> > --
> > 2.17.1
> >
next prev parent reply other threads:[~2022-04-20 3:17 UTC|newest]
Thread overview: 117+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-10 14:08 [PATCH v5 00/13] KVM: mm: fd-based approach for supporting KVM guest private memory Chao Peng
2022-03-10 14:08 ` [PATCH v5 01/13] mm/memfd: Introduce MFD_INACCESSIBLE flag Chao Peng
2022-04-11 15:10 ` Kirill A. Shutemov
2022-04-12 13:11 ` Chao Peng
2022-04-23 5:43 ` Vishal Annapurve
2022-04-24 8:15 ` Chao Peng
2022-03-10 14:09 ` [PATCH v5 02/13] mm: Introduce memfile_notifier Chao Peng
2022-03-29 18:45 ` Sean Christopherson
2022-04-08 12:54 ` Chao Peng
[not found] ` <20220412143654.6313-1-hdanton@sina.com>
2022-04-13 6:47 ` Chao Peng
2022-03-10 14:09 ` [PATCH v5 03/13] mm/shmem: Support memfile_notifier Chao Peng
2022-03-10 23:08 ` Dave Chinner
2022-03-11 8:42 ` Chao Peng
2022-04-11 15:26 ` Kirill A. Shutemov
2022-04-12 13:12 ` Chao Peng
2022-04-19 22:40 ` Vishal Annapurve
2022-04-20 3:24 ` Chao Peng
2022-03-10 14:09 ` [PATCH v5 04/13] mm/shmem: Restrict MFD_INACCESSIBLE memory against RLIMIT_MEMLOCK Chao Peng
2022-04-07 16:05 ` Sean Christopherson
2022-04-07 17:09 ` Andy Lutomirski
2022-04-08 17:56 ` Sean Christopherson
2022-04-08 18:54 ` David Hildenbrand
2022-04-12 14:36 ` Jason Gunthorpe
2022-04-12 21:27 ` Andy Lutomirski
2022-04-13 16:30 ` David Hildenbrand
2022-04-13 16:24 ` David Hildenbrand
2022-04-13 17:52 ` Jason Gunthorpe
2022-04-25 14:07 ` David Hildenbrand
2022-04-08 13:02 ` Chao Peng
2022-04-11 15:34 ` Kirill A. Shutemov
2022-04-12 5:14 ` Hugh Dickins
2022-04-11 15:32 ` Kirill A. Shutemov
2022-04-12 13:39 ` Chao Peng
2022-04-12 19:28 ` Kirill A. Shutemov
2022-04-13 9:15 ` Chao Peng
2022-03-10 14:09 ` [PATCH v5 05/13] KVM: Extend the memslot to support fd-based private memory Chao Peng
2022-03-28 21:27 ` Sean Christopherson
2022-04-08 13:21 ` Chao Peng
2022-03-28 21:56 ` Sean Christopherson
2022-04-08 13:46 ` Chao Peng
2022-04-08 17:45 ` Sean Christopherson
2022-03-10 14:09 ` [PATCH v5 06/13] KVM: Use kvm_userspace_memory_region_ext Chao Peng
2022-03-28 22:26 ` Sean Christopherson
2022-04-08 13:58 ` Chao Peng
2022-03-10 14:09 ` [PATCH v5 07/13] KVM: Add KVM_EXIT_MEMORY_ERROR exit Chao Peng
2022-03-28 22:33 ` Sean Christopherson
2022-04-08 13:59 ` Chao Peng
2022-03-10 14:09 ` [PATCH v5 08/13] KVM: Use memfile_pfn_ops to obtain pfn for private pages Chao Peng
2022-03-28 23:56 ` Sean Christopherson
2022-04-08 14:07 ` Chao Peng
2022-04-28 12:37 ` Chao Peng
2022-03-10 14:09 ` [PATCH v5 09/13] KVM: Handle page fault for private memory Chao Peng
2022-03-29 1:07 ` Sean Christopherson
2022-04-12 12:10 ` Chao Peng
2022-03-10 14:09 ` [PATCH v5 10/13] KVM: Register private memslot to memory backing store Chao Peng
2022-03-29 19:01 ` Sean Christopherson
2022-04-12 12:40 ` Chao Peng
2022-03-10 14:09 ` [PATCH v5 11/13] KVM: Zap existing KVM mappings when pages changed in the private fd Chao Peng
2022-03-29 19:23 ` Sean Christopherson
2022-04-12 12:43 ` Chao Peng
2022-04-05 23:45 ` Michael Roth
2022-04-08 3:06 ` Sean Christopherson
2022-04-19 22:43 ` Vishal Annapurve
2022-04-20 3:17 ` Chao Peng [this message]
2022-03-10 14:09 ` [PATCH v5 12/13] KVM: Expose KVM_MEM_PRIVATE Chao Peng
2022-03-29 19:13 ` Sean Christopherson
2022-04-12 12:56 ` Chao Peng
2022-03-10 14:09 ` [PATCH v5 13/13] memfd_create.2: Describe MFD_INACCESSIBLE flag Chao Peng
2022-03-24 15:51 ` [PATCH v5 00/13] KVM: mm: fd-based approach for supporting KVM guest private memory Quentin Perret
2022-03-28 17:13 ` Sean Christopherson
2022-03-28 18:00 ` Quentin Perret
2022-03-28 18:58 ` Sean Christopherson
2022-03-29 17:01 ` Quentin Perret
2022-03-30 8:58 ` Steven Price
2022-03-30 10:39 ` Quentin Perret
2022-03-30 17:58 ` Sean Christopherson
2022-03-31 16:04 ` Andy Lutomirski
2022-04-01 14:59 ` Quentin Perret
2022-04-01 17:14 ` Sean Christopherson
2022-04-01 18:03 ` Quentin Perret
2022-04-01 18:24 ` Sean Christopherson
2022-04-01 19:56 ` Andy Lutomirski
2022-04-04 15:01 ` Quentin Perret
2022-04-04 17:06 ` Sean Christopherson
2022-04-04 22:04 ` Andy Lutomirski
2022-04-05 10:36 ` Quentin Perret
2022-04-05 17:51 ` Andy Lutomirski
2022-04-05 18:30 ` Sean Christopherson
2022-04-06 18:42 ` Andy Lutomirski
2022-04-06 13:05 ` Quentin Perret
2022-04-05 18:03 ` Sean Christopherson
2022-04-06 10:34 ` Quentin Perret
2022-04-22 10:56 ` Chao Peng
2022-04-22 11:06 ` Paolo Bonzini
2022-04-24 8:07 ` Chao Peng
2022-04-24 16:59 ` Andy Lutomirski
2022-04-25 13:40 ` Chao Peng
2022-04-25 14:52 ` Andy Lutomirski
2022-04-25 20:30 ` Sean Christopherson
2022-06-10 19:18 ` Andy Lutomirski
2022-06-10 19:27 ` Sean Christopherson
2022-04-28 12:29 ` Chao Peng
2022-05-03 11:12 ` Quentin Perret
2022-05-09 22:30 ` Michael Roth
2022-05-09 23:29 ` Sean Christopherson
2022-07-21 20:05 ` Gupta, Pankaj
2022-07-21 21:19 ` Sean Christopherson
2022-07-21 21:36 ` Gupta, Pankaj
2022-07-23 3:09 ` Andy Lutomirski
2022-07-25 9:19 ` Gupta, Pankaj
2022-03-30 16:18 ` Sean Christopherson
2022-03-28 20:16 ` Andy Lutomirski
2022-03-28 22:48 ` Nakajima, Jun
2022-03-29 0:04 ` Sean Christopherson
2022-04-08 21:35 ` Vishal Annapurve
2022-04-12 13:00 ` Chao Peng
2022-04-12 19:58 ` Kirill A. Shutemov
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