Commit b53846c5 authored by Quentin Perret's avatar Quentin Perret Committed by Marc Zyngier
Browse files

KVM: arm64: Tolerate re-creating hyp mappings to set software bits 



The current hypervisor stage-1 mapping code doesn't allow changing an
existing valid mapping. Relax this condition by allowing changes that
only target software bits, as that will soon be needed to annotate shared
pages.

Reviewed-by: default avatarFuad Tabba <tabba@google.com>
Signed-off-by: default avatarQuentin Perret <qperret@google.com>
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210809152448.1810400-10-qperret@google.com
parent 8a0282c6

arch/arm64/kvm/hyp/pgtable.c

+16 −2
Original line number Diff line number Diff line
@@ -362,6 +362,21 @@ static int hyp_set_prot_attr(enum kvm_pgtable_prot prot, kvm_pte_t *ptep) 
	return 0;

}



static bool hyp_pte_needs_update(kvm_pte_t old, kvm_pte_t new)

{

	/*

	 * Tolerate KVM recreating the exact same mapping, or changing software

	 * bits if the existing mapping was valid.

	 */

	if (old == new)

		return false;



	if (!kvm_pte_valid(old))

		return true;



	return !WARN_ON((old ^ new) & ~KVM_PTE_LEAF_ATTR_HI_SW);

}



static bool hyp_map_walker_try_leaf(u64 addr, u64 end, u32 level,

				    kvm_pte_t *ptep, struct hyp_map_data *data)

{
@@ -371,9 +386,8 @@ static bool hyp_map_walker_try_leaf(u64 addr, u64 end, u32 level, 
	if (!kvm_block_mapping_supported(addr, end, phys, level))

		return false;



	/* Tolerate KVM recreating the exact same mapping */

	new = kvm_init_valid_leaf_pte(phys, data->attr, level);

	if (old != new && !WARN_ON(kvm_pte_valid(old)))

	if (hyp_pte_needs_update(old, new))

		smp_store_release(ptep, new);



	data->phys += granule;