The current implementation of the stage-2 unmap walker traverses
the given range and, as a part of break-before-make, performs
TLB invalidations with a DSB for every PTE. A multitude of this
combination could cause a performance bottleneck.
Hence, if the system supports FEAT_TLBIRANGE, defer the TLB
invalidations until the entire walk is finished, and then
use range-based instructions to invalidate the TLBs in one go.
Condition this upon S2FWB in order to avoid walking the page-table
again to perform the CMOs after issuing the TLBI.
Signed-off-by: Raghavendra Rao Ananta <rananta@xxxxxxxxxx>
Suggested-by: Oliver Upton <oliver.upton@xxxxxxxxx>
---
arch/arm64/kvm/hyp/pgtable.c | 33 +++++++++++++++++++++++++++++----
1 file changed, 29 insertions(+), 4 deletions(-)
diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index 3f136e35feb5e..bcb748e3566c7 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -987,10 +987,16 @@ int kvm_pgtable_stage2_set_owner(struct kvm_pgtable *pgt, u64 addr, u64 size,
return ret;
}
+struct stage2_unmap_data {
+ struct kvm_pgtable *pgt;
+ bool skip_pte_tlbis;
+};
+
static int stage2_unmap_walker(const struct kvm_pgtable_visit_ctx *ctx,
enum kvm_pgtable_walk_flags visit)
{
- struct kvm_pgtable *pgt = ctx->arg;
+ struct stage2_unmap_data *unmap_data = ctx->arg;
+ struct kvm_pgtable *pgt = unmap_data->pgt;
struct kvm_s2_mmu *mmu = pgt->mmu;
struct kvm_pgtable_mm_ops *mm_ops = ctx->mm_ops;
kvm_pte_t *childp = NULL;
@@ -1018,7 +1024,7 @@ static int stage2_unmap_walker(const struct kvm_pgtable_visit_ctx *ctx,
* block entry and rely on the remaining portions being faulted
* back lazily.
*/
- stage2_put_pte(ctx, mmu, mm_ops, false);
+ stage2_put_pte(ctx, mmu, mm_ops, unmap_data->skip_pte_tlbis);
if (need_flush && mm_ops->dcache_clean_inval_poc)
mm_ops->dcache_clean_inval_poc(kvm_pte_follow(ctx->old, mm_ops),
@@ -1032,13 +1038,32 @@ static int stage2_unmap_walker(const struct kvm_pgtable_visit_ctx *ctx,
int kvm_pgtable_stage2_unmap(struct kvm_pgtable *pgt, u64 addr, u64 size)
{
+ int ret;
+ struct stage2_unmap_data unmap_data = {
+ .pgt = pgt,
+ /*
+ * If FEAT_TLBIRANGE is implemented, defer the individial PTE
+ * TLB invalidations until the entire walk is finished, and
+ * then use the range-based TLBI instructions to do the
+ * invalidations. Condition this upon S2FWB in order to avoid
+ * a page-table walk again to perform the CMOs after TLBI.
+ */
+ .skip_pte_tlbis = system_supports_tlb_range() &&
+ stage2_has_fwb(pgt),
+ };
struct kvm_pgtable_walker walker = {
.cb = stage2_unmap_walker,
- .arg = pgt,
+ .arg = &unmap_data,
.flags = KVM_PGTABLE_WALK_LEAF | KVM_PGTABLE_WALK_TABLE_POST,
};
- return kvm_pgtable_walk(pgt, addr, size, &walker);
+ ret = kvm_pgtable_walk(pgt, addr, size, &walker);
+ if (unmap_data.skip_pte_tlbis)
+ /* Perform the deferred TLB invalidations */
+ kvm_call_hyp(__kvm_tlb_flush_vmid_range, pgt->mmu,
+ addr, addr + size);
+
+ return ret;
}
struct stage2_attr_data {
--
2.40.0.634.g4ca3ef3211-goog
