Re: [PATCH v10 02/41] KVM: guest_memfd: Introduce per-gmem attributes, use to guard user mappings
From: Binbin Wu <hidden>
Date: 2026-08-12 03:27:52
Also in:
kvm, linux-coco, linux-doc, linux-kselftest, linux-mm, lkml
On 8/8/2026 5:52 AM, Ackerley Tng via B4 Relay wrote:
From: Sean Christopherson <seanjc@google.com> Start plumbing in guest_memfd support for in-place private<=>shared conversions by tracking attributes via a maple tree. KVM currently tracks private vs. shared attributes on a per-VM basis, which made sense when a guest_memfd _only_ supported private memory, but tracking per-VM simply can't work for in-place conversions as the shared/private status of a given page needs to be per-gmem_inode, not per-VM. Use the filemap invalidation lock to protect the maple tree, as taking the lock for read when faulting in memory (for userspace or the guest) isn't expected to result in meaningful contention, and using a separate lock would add significant complexity (avoiding deadlock is quite difficult). Co-developed-by: Vishal Annapurve <redacted> Signed-off-by: Vishal Annapurve <redacted> Co-developed-by: Fuad Tabba <redacted> Signed-off-by: Fuad Tabba <redacted> Signed-off-by: Sean Christopherson <seanjc@google.com> Tested-by: Shivank Garg <redacted> Reviewed-by: Xiaoyao Li <redacted> Co-developed-by: Ackerley Tng <redacted> Signed-off-by: Ackerley Tng <redacted>
With Sean's fixup in https://lore.kernel.org/kvm/annqex-kBOc0UJvp@google.com/ (local) Reviewed-by: Binbin Wu <redacted>