[PATCH 06/14] KVM: arm64: Tolerate re-creating hyp mappings to set ignored bits
From: Quentin Perret <hidden>
Date: 2021-07-19 10:48:04
Also in:
kvmarm, lkml
Subsystem:
arm64 port (aarch64 architecture), kernel virtual machine for arm64 (kvm/arm64), the rest · Maintainers:
Catalin Marinas, Will Deacon, Marc Zyngier, Oliver Upton, Linus Torvalds
The current hypervisor stage-1 mapping code doesn't allow changing an existing valid mapping. Relax this condition by allowing changes that only target ignored bits, as that will soon be needed to annotate shared pages. Signed-off-by: Quentin Perret <redacted> --- arch/arm64/kvm/hyp/pgtable.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index a0ac8c2bc174..34cf67997a82 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c@@ -362,6 +362,17 @@ 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) +{ + if (old == new) + return false; + + if (!kvm_pte_valid(old)) + return true; + + return !WARN_ON((old ^ new) & ~KVM_PTE_LEAF_ATTR_IGNORED); +} + static bool hyp_map_walker_try_leaf(u64 addr, u64 end, u32 level, kvm_pte_t *ptep, struct hyp_map_data *data) {
@@ -371,9 +382,12 @@ 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 */ + /* + * Tolerate KVM recreating the exact same mapping, or changing ignored + * bits. + */ 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;
--
2.32.0.402.g57bb445576-goog
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