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.
Rename stage2_put_pte() to stage2_unmap_put_pte() as the function
now serves the stage-2 unmap walker specifically, rather than
acting generic.
Signed-off-by: Raghavendra Rao Ananta <rananta@xxxxxxxxxx>
---
arch/arm64/kvm/hyp/pgtable.c | 35 ++++++++++++++++++++++++++++++-----
1 file changed, 30 insertions(+), 5 deletions(-)
diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index b8f0dbd12f773..5832ee3418fb0 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -771,16 +771,34 @@ static void stage2_make_pte(const struct kvm_pgtable_visit_ctx *ctx, kvm_pte_t n
smp_store_release(ctx->ptep, new);
}
-static void stage2_put_pte(const struct kvm_pgtable_visit_ctx *ctx, struct kvm_s2_mmu *mmu,
- struct kvm_pgtable_mm_ops *mm_ops)
+static bool stage2_unmap_defer_tlb_flush(struct kvm_pgtable *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.
+ */
+ return system_supports_tlb_range() && stage2_has_fwb(pgt);
+}
+
+static void stage2_unmap_put_pte(const struct kvm_pgtable_visit_ctx *ctx,
+ struct kvm_s2_mmu *mmu,
+ struct kvm_pgtable_mm_ops *mm_ops)
+{
+ struct kvm_pgtable *pgt = ctx->arg;
+
/*
* Clear the existing PTE, and perform break-before-make with
* TLB maintenance if it was valid.
*/
if (kvm_pte_valid(ctx->old)) {
kvm_clear_pte(ctx->ptep);
- kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, mmu, ctx->addr, ctx->level);
+
+ if (!stage2_unmap_defer_tlb_flush(pgt))
+ kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, mmu,
+ ctx->addr, ctx->level);
}
mm_ops->put_page(ctx->ptep);
@@ -1015,7 +1033,7 @@ 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);
+ stage2_unmap_put_pte(ctx, mmu, mm_ops);
if (need_flush && mm_ops->dcache_clean_inval_poc)
mm_ops->dcache_clean_inval_poc(kvm_pte_follow(ctx->old, mm_ops),
@@ -1029,13 +1047,20 @@ 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 kvm_pgtable_walker walker = {
.cb = stage2_unmap_walker,
.arg = pgt,
.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 (stage2_unmap_defer_tlb_flush(pgt))
+ /* Perform the deferred TLB invalidations */
+ kvm_call_hyp(__kvm_tlb_flush_vmid_range, pgt->mmu,
+ addr, addr + size);
+
+ return ret;
}
struct stage2_attr_data {
--
2.40.1.698.g37aff9b760-goog
