From: "Maciej S. Szmigiero" <mail@maciej.szmigiero.name>
To: Chao Peng <chao.p.peng@linux.intel.com>,
Yu Zhang <yu.c.zhang@linux.intel.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org, 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>,
kvm@vger.kernel.org, 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>,
"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, qemu-devel@nongnu.org
Subject: Re: [PATCH v4 12/12] KVM: Expose KVM_MEM_PRIVATE
Date: Tue, 25 Jan 2022 21:20:39 +0100 [thread overview]
Message-ID: <a121e766-900d-2135-1516-e1d3ba716834@maciej.szmigiero.name> (raw)
In-Reply-To: <20220118132121.31388-13-chao.p.peng@linux.intel.com>
On 18.01.2022 14:21, Chao Peng wrote:
> KVM_MEM_PRIVATE is not exposed by default but architecture code can turn
> on it by implementing kvm_arch_private_memory_supported().
>
> Also private memslot cannot be movable and the same file+offset can not
> be mapped into different GFNs.
>
> Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>
> Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com>
> ---
(..)
>
> static bool kvm_check_memslot_overlap(struct kvm_memslots *slots, int id,
> - gfn_t start, gfn_t end)
> + struct file *file,
> + gfn_t start, gfn_t end,
> + loff_t start_off, loff_t end_off)
> {
> struct kvm_memslot_iter iter;
> + struct kvm_memory_slot *slot;
> + struct inode *inode;
> + int bkt;
>
> kvm_for_each_memslot_in_gfn_range(&iter, slots, start, end) {
> if (iter.slot->id != id)
> return true;
> }
>
> + /* Disallow mapping the same file+offset into multiple gfns. */
> + if (file) {
> + inode = file_inode(file);
> + kvm_for_each_memslot(slot, bkt, slots) {
> + if (slot->private_file &&
> + file_inode(slot->private_file) == inode &&
> + !(end_off <= slot->private_offset ||
> + start_off >= slot->private_offset
> + + (slot->npages >> PAGE_SHIFT)))
> + return true;
> + }
> + }
That's a linear scan of all memslots on each CREATE (and MOVE) operation
with a fd - we just spent more than a year rewriting similar linear scans
into more efficient operations in KVM.
Thanks,
Maciej
next prev parent reply other threads:[~2022-01-25 20:21 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-18 13:21 [PATCH v4 00/12] KVM: mm: fd-based approach for supporting KVM guest private memory Chao Peng
2022-01-18 13:21 ` [PATCH v4 01/12] mm/shmem: Introduce F_SEAL_INACCESSIBLE Chao Peng
2022-02-07 12:24 ` Vlastimil Babka
2022-02-17 12:56 ` Chao Peng
2022-02-11 23:33 ` Andy Lutomirski
2022-02-17 13:06 ` Chao Peng
2022-02-17 19:09 ` Andy Lutomirski
2022-02-23 11:49 ` Chao Peng
2022-02-23 12:05 ` Steven Price
2022-03-04 19:24 ` Andy Lutomirski
2022-03-07 13:26 ` Chao Peng
2022-03-08 12:17 ` Paolo Bonzini
2022-01-18 13:21 ` [PATCH v4 02/12] mm/memfd: Introduce MFD_INACCESSIBLE flag Chao Peng
2022-01-21 15:50 ` Steven Price
2022-01-24 13:29 ` Chao Peng
2022-02-07 18:51 ` Vlastimil Babka
2022-02-08 8:49 ` David Hildenbrand
2022-02-08 18:22 ` Mike Rapoport
2022-01-18 13:21 ` [PATCH v4 03/12] mm: Introduce memfile_notifier Chao Peng
2022-03-07 15:42 ` Vlastimil Babka
2022-03-08 1:45 ` Chao Peng
2022-01-18 13:21 ` [PATCH v4 04/12] mm/shmem: Support memfile_notifier Chao Peng
2022-02-08 18:29 ` Mike Rapoport
2022-02-17 13:10 ` Chao Peng
2022-02-11 23:40 ` Andy Lutomirski
2022-02-17 13:23 ` Chao Peng
2022-01-18 13:21 ` [PATCH v4 05/12] KVM: Extend the memslot to support fd-based private memory Chao Peng
2022-01-18 13:21 ` [PATCH v4 06/12] KVM: Use kvm_userspace_memory_region_ext Chao Peng
2022-01-18 13:21 ` [PATCH v4 07/12] KVM: Add KVM_EXIT_MEMORY_ERROR exit Chao Peng
2022-01-18 13:21 ` [PATCH v4 08/12] KVM: Use memfile_pfn_ops to obtain pfn for private pages Chao Peng
2022-01-18 13:21 ` [PATCH v4 09/12] KVM: Handle page fault for private memory Chao Peng
2022-01-18 13:21 ` [PATCH v4 10/12] KVM: Register private memslot to memory backing store Chao Peng
2022-01-18 13:21 ` [PATCH v4 11/12] KVM: Zap existing KVM mappings when pages changed in the private fd Chao Peng
2022-01-18 13:21 ` [PATCH v4 12/12] KVM: Expose KVM_MEM_PRIVATE Chao Peng
2022-01-25 20:20 ` Maciej S. Szmigiero [this message]
2022-02-17 13:45 ` Chao Peng
2022-02-22 1:16 ` Maciej S. Szmigiero
2022-02-23 12:00 ` Chao Peng
2022-02-23 18:32 ` Maciej S. Szmigiero
2022-02-24 8:07 ` Chao Peng
2022-01-28 16:47 ` [PATCH v4 00/12] KVM: mm: fd-based approach for supporting KVM guest private memory Steven Price
2022-02-02 2:28 ` Nakajima, Jun
2022-02-02 9:23 ` Steven Price
2022-02-02 20:47 ` Nakajima, Jun
2022-02-08 18:33 ` Mike Rapoport
2022-02-17 13:47 ` Chao Peng
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