Rob Bradford 49259bb84f hypervisor: kvm: Punch holes in guest_memfd on shared transition ...

When an SEV-SNP guest transitions pages from private to shared via
KVM_HC_MAP_GPA_RANGE, punch holes in the corresponding guest_memfd
backing it. Without this the balloon driver's `set_memory_decrypted()`
path transitions the page attributes but the physical memory stays
pinned in guest_memfd, making virtio-balloon ineffective for memory
overcommit with confidential VMs. Even without ballooning these pages
are unused by the guest so consume resources. This mirrors the hole
punching that the balloon device does for releasing pages.

The memory_slots Arc is cloned into each KvmVcpu at creation so the
punch can happen in the vcpu thread.

Assisted-by: Claude:claude-opus-4-6
Signed-off-by: Rob Bradford <rbradford@meta.com>

2026-05-07 22:48:06 +00:00

..

src

hypervisor: kvm: Punch holes in guest_memfd on shared transition

2026-05-07 22:48:06 +00:00

Cargo.toml

build(deps): bump the non-rust-vmm group across 2 directories with 22 updates

2026-04-24 00:47:54 +00:00