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-arch@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>,
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>,
Shuah Khan <shuah@kernel.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>,
luto@kernel.org, jun.nakajima@intel.com, dave.hansen@intel.com,
ak@linux.intel.com, david@redhat.com, aarcange@redhat.com,
ddutile@redhat.com, dhildenb@redhat.com,
Quentin Perret <qperret@google.com>,
tabba@google.com, Michael Roth <michael.roth@amd.com>,
mhocko@suse.com, Muchun Song <songmuchun@bytedance.com>,
wei.w.wang@intel.com
Subject: Re: [PATCH v9 1/8] mm: Introduce memfd_restricted system call to create restricted user memory
Date: Fri, 2 Dec 2022 14:49:09 +0800 [thread overview]
Message-ID: <20221202064909.GA1070297@chaop.bj.intel.com> (raw)
In-Reply-To: <CAGtprH9Qu==pohH9ZSTzX9rZWSO0QWJ9rGK6NRGaiDetWAPLYg@mail.gmail.com>
On Thu, Dec 01, 2022 at 06:16:46PM -0800, Vishal Annapurve wrote:
> On Tue, Oct 25, 2022 at 8:18 AM Chao Peng <chao.p.peng@linux.intel.com> wrote:
> >
...
> > +}
> > +
> > +SYSCALL_DEFINE1(memfd_restricted, unsigned int, flags)
> > +{
>
> Looking at the underlying shmem implementation, there seems to be no
> way to enable transparent huge pages specifically for restricted memfd
> files.
>
> Michael discussed earlier about tweaking
> /sys/kernel/mm/transparent_hugepage/shmem_enabled setting to allow
> hugepages to be used while backing restricted memfd. Such a change
> will affect the rest of the shmem usecases as well. Even setting the
> shmem_enabled policy to "advise" wouldn't help unless file based
> advise for hugepage allocation is implemented.
Had a look at fadvise() and looks it does not support HUGEPAGE for any
filesystem yet.
>
> Does it make sense to provide a flag here to allow creating restricted
> memfds backed possibly by huge pages to give a more granular control?
We do have a unused 'flags' can be extended for such usage, but I would
let Kirill have further look, perhaps need more discussions.
Chao
>
> > + struct file *file, *restricted_file;
> > + int fd, err;
> > +
> > + if (flags)
> > + return -EINVAL;
> > +
> > + fd = get_unused_fd_flags(0);
> > + if (fd < 0)
> > + return fd;
> > +
> > + file = shmem_file_setup("memfd:restrictedmem", 0, VM_NORESERVE);
> > + if (IS_ERR(file)) {
> > + err = PTR_ERR(file);
> > + goto err_fd;
> > + }
> > + file->f_mode |= FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE;
> > + file->f_flags |= O_LARGEFILE;
> > +
> > + restricted_file = restrictedmem_file_create(file);
> > + if (IS_ERR(restricted_file)) {
> > + err = PTR_ERR(restricted_file);
> > + fput(file);
> > + goto err_fd;
> > + }
> > +
> > + fd_install(fd, restricted_file);
> > + return fd;
> > +err_fd:
> > + put_unused_fd(fd);
> > + return err;
> > +}
> > +
> > +void restrictedmem_register_notifier(struct file *file,
> > + struct restrictedmem_notifier *notifier)
> > +{
> > + struct restrictedmem_data *data = file->f_mapping->private_data;
> > +
> > + mutex_lock(&data->lock);
> > + list_add(¬ifier->list, &data->notifiers);
> > + mutex_unlock(&data->lock);
> > +}
> > +EXPORT_SYMBOL_GPL(restrictedmem_register_notifier);
> > +
> > +void restrictedmem_unregister_notifier(struct file *file,
> > + struct restrictedmem_notifier *notifier)
> > +{
> > + struct restrictedmem_data *data = file->f_mapping->private_data;
> > +
> > + mutex_lock(&data->lock);
> > + list_del(¬ifier->list);
> > + mutex_unlock(&data->lock);
> > +}
> > +EXPORT_SYMBOL_GPL(restrictedmem_unregister_notifier);
> > +
> > +int restrictedmem_get_page(struct file *file, pgoff_t offset,
> > + struct page **pagep, int *order)
> > +{
> > + struct restrictedmem_data *data = file->f_mapping->private_data;
> > + struct file *memfd = data->memfd;
> > + struct page *page;
> > + int ret;
> > +
> > + ret = shmem_getpage(file_inode(memfd), offset, &page, SGP_WRITE);
> > + if (ret)
> > + return ret;
> > +
> > + *pagep = page;
> > + if (order)
> > + *order = thp_order(compound_head(page));
> > +
> > + SetPageUptodate(page);
> > + unlock_page(page);
> > +
> > + return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(restrictedmem_get_page);
> > --
> > 2.25.1
> >
next prev parent reply other threads:[~2022-12-02 6:53 UTC|newest]
Thread overview: 101+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-25 15:13 [PATCH v9 0/8] KVM: mm: fd-based approach for supporting KVM Chao Peng
2022-10-25 15:13 ` [PATCH v9 1/8] mm: Introduce memfd_restricted system call to create restricted user memory Chao Peng
2022-10-26 17:31 ` Isaku Yamahata
2022-10-28 6:12 ` Chao Peng
2022-10-27 10:20 ` Fuad Tabba
2022-10-31 17:47 ` Michael Roth
2022-11-01 11:37 ` Chao Peng
2022-11-01 15:19 ` Michael Roth
2022-11-01 19:30 ` Michael Roth
2022-11-02 14:53 ` Chao Peng
2022-11-02 21:19 ` Michael Roth
2022-11-14 14:02 ` Vlastimil Babka
2022-11-14 15:28 ` Kirill A. Shutemov
2022-11-14 22:16 ` Michael Roth
2022-11-15 9:48 ` Chao Peng
2022-11-14 22:16 ` Michael Roth
2022-11-02 21:14 ` Kirill A. Shutemov
2022-11-02 21:26 ` Michael Roth
2022-11-02 22:07 ` Michael Roth
2022-11-03 16:30 ` Kirill A. Shutemov
2022-11-29 0:06 ` Michael Roth
2022-11-29 11:21 ` Kirill A. Shutemov
2022-11-29 11:39 ` David Hildenbrand
2022-11-29 13:59 ` Chao Peng
2022-11-29 13:58 ` Chao Peng
2022-11-29 0:37 ` Michael Roth
2022-11-29 14:06 ` Chao Peng
2022-11-29 19:06 ` Michael Roth
2022-11-29 19:18 ` Michael Roth
2022-11-30 9:39 ` Chao Peng
2022-11-30 14:31 ` Michael Roth
2022-11-29 18:01 ` Vishal Annapurve
2022-12-02 2:16 ` Vishal Annapurve
2022-12-02 6:49 ` Chao Peng [this message]
2022-12-02 13:44 ` Kirill A . Shutemov
2022-10-25 15:13 ` [PATCH v9 2/8] KVM: Extend the memslot to support fd-based private memory Chao Peng
2022-10-27 10:25 ` Fuad Tabba
2022-10-28 7:04 ` Xiaoyao Li
2022-10-31 14:14 ` Chao Peng
2022-11-14 16:04 ` Alex Bennée
2022-11-15 9:29 ` Chao Peng
2022-10-25 15:13 ` [PATCH v9 3/8] KVM: Add KVM_EXIT_MEMORY_FAULT exit Chao Peng
2022-10-25 15:26 ` Peter Maydell
2022-10-25 16:17 ` Sean Christopherson
2022-10-27 10:27 ` Fuad Tabba
2022-10-28 6:14 ` Chao Peng
2022-11-15 16:56 ` Alex Bennée
2022-11-16 3:14 ` Chao Peng
2022-11-16 19:03 ` Alex Bennée
2022-11-17 13:45 ` Chao Peng
2022-11-17 15:08 ` Alex Bennée
2022-11-18 1:32 ` Chao Peng
2022-11-18 13:23 ` Alex Bennée
2022-11-18 15:59 ` Sean Christopherson
2022-11-22 9:50 ` Chao Peng
2022-11-23 18:02 ` Sean Christopherson
2022-11-16 18:15 ` Andy Lutomirski
2022-11-16 18:48 ` Sean Christopherson
2022-11-17 13:42 ` Chao Peng
2022-10-25 15:13 ` [PATCH v9 4/8] KVM: Use gfn instead of hva for mmu_notifier_retry Chao Peng
2022-10-27 10:29 ` Fuad Tabba
2022-11-04 2:28 ` Chao Peng
2022-11-04 22:29 ` Sean Christopherson
2022-11-08 7:16 ` Chao Peng
2022-11-10 17:53 ` Sean Christopherson
2022-11-10 20:06 ` Sean Christopherson
2022-11-11 8:27 ` Chao Peng
2022-10-25 15:13 ` [PATCH v9 5/8] KVM: Register/unregister the guest private memory regions Chao Peng
2022-10-27 10:31 ` Fuad Tabba
2022-11-03 23:04 ` Sean Christopherson
2022-11-04 8:28 ` Chao Peng
2022-11-04 21:19 ` Sean Christopherson
2022-11-08 8:24 ` Chao Peng
2022-11-08 1:35 ` Yuan Yao
2022-11-08 9:41 ` Chao Peng
2022-11-09 5:52 ` Yuan Yao
2022-11-16 22:24 ` Sean Christopherson
2022-11-17 13:20 ` Chao Peng
2022-10-25 15:13 ` [PATCH v9 6/8] KVM: Update lpage info when private/shared memory are mixed Chao Peng
2022-10-26 20:46 ` Isaku Yamahata
2022-10-28 6:38 ` Chao Peng
2022-11-08 12:08 ` Yuan Yao
2022-11-09 4:13 ` Chao Peng
2022-10-25 15:13 ` [PATCH v9 7/8] KVM: Handle page fault for private memory Chao Peng
2022-10-26 21:54 ` Isaku Yamahata
2022-10-28 6:55 ` Chao Peng
2022-11-01 0:02 ` Isaku Yamahata
2022-11-01 11:38 ` Chao Peng
2022-11-16 20:50 ` Ackerley Tng
2022-11-16 22:13 ` Sean Christopherson
2022-11-17 13:25 ` Chao Peng
2022-10-25 15:13 ` [PATCH v9 8/8] KVM: Enable and expose KVM_MEM_PRIVATE Chao Peng
2022-10-27 10:31 ` Fuad Tabba
2022-11-03 12:13 ` [PATCH v9 0/8] KVM: mm: fd-based approach for supporting KVM Vishal Annapurve
2022-11-08 0:41 ` Isaku Yamahata
2022-11-09 15:54 ` Kirill A. Shutemov
2022-11-15 14:36 ` Kirill A. Shutemov
2022-11-14 11:43 ` Alex Bennée
2022-11-16 5:00 ` Chao Peng
2022-11-16 9:40 ` Alex Bennée
2022-11-17 14:16 ` Chao Peng
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