Commit 244acf19 authored by Fuad Tabba's avatar Fuad Tabba Committed by Marc Zyngier
Browse files

KVM: arm64: Fix vma_shift staleness on nested hwpoison path 



When user_mem_abort() handles a nested stage-2 fault, it truncates
vma_pagesize to respect the guest's mapping size. However, the local
variable vma_shift is never updated to match this new size.

If the underlying host page turns out to be hardware poisoned,
kvm_send_hwpoison_signal() is called with the original, larger
vma_shift instead of the actual mapping size. This signals incorrect
poison boundaries to userspace and breaks hugepage memory poison
containment for nested VMs.

Update vma_shift to match the truncated vma_pagesize when operating
on behalf of a nested hypervisor.

Fixes: fd276e71 ("KVM: arm64: nv: Handle shadow stage 2 page faults")
Signed-off-by: default avatarFuad Tabba <tabba@google.com>
Link: https://patch.msgid.link/20260304162222.836152-3-tabba@google.com


[maz: simplified vma_shift assignment from the original patch]
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
parent e07fc9e2

arch/arm64/kvm/mmu.c

+1 −0
Original line number Diff line number Diff line
@@ -1751,6 +1751,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, 


		force_pte = (max_map_size == PAGE_SIZE);

		vma_pagesize = min_t(long, vma_pagesize, max_map_size);

		vma_shift = __ffs(vma_pagesize);

	}



	/*