Hi Raghavendra,
On Fri, Apr 14, 2023 at 05:29:21PM +0000, Raghavendra Rao Ananta wrote:
> Add a 'skip_flush' argument in stage2_put_pte() to
> control the TLB invalidations. This will be leveraged
> by the upcoming patch to defer the individual PTE
> invalidations until the entire walk is finished.
>
> No functional change intended.
>
> Signed-off-by: Raghavendra Rao Ananta <rananta@xxxxxxxxxx>
> ---
> arch/arm64/kvm/hyp/pgtable.c | 9 ++++++---
> 1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
> index b8f0dbd12f773..3f136e35feb5e 100644
> --- a/arch/arm64/kvm/hyp/pgtable.c
> +++ b/arch/arm64/kvm/hyp/pgtable.c
> @@ -772,7 +772,7 @@ static void stage2_make_pte(const struct kvm_pgtable_visit_ctx *ctx, kvm_pte_t n
> }
>
> static void stage2_put_pte(const struct kvm_pgtable_visit_ctx *ctx, struct kvm_s2_mmu *mmu,
> - struct kvm_pgtable_mm_ops *mm_ops)
> + struct kvm_pgtable_mm_ops *mm_ops, bool skip_flush)
Assuming you are going to pull the cpufeature checks into this helper,
it might me helpful to narrow the scope of it. 'stage2_put_pte()' sounds
very generic, but it is about to have a very precise meaning in relation
to kvm_pgtable_stage2_unmap().
So maybe stage2_unmap_put_pte()? While at it, you'd want to have a
shared helper for the deferral check:
static bool stage2_unmap_defer_tlb_flush(struct kvm_pgtable *pgt)
{
/* your blurb for why FWB is required too */
return system_supports_tlb_range() && stage2_has_fwb(pgt);
}
The 'flush' part is annoying, because the exact term is an invalidation,
but we already have that pattern in all of our TLB invalidation helpers.
> {
> /*
> * Clear the existing PTE, and perform break-before-make with
> @@ -780,7 +780,10 @@ static void stage2_put_pte(const struct kvm_pgtable_visit_ctx *ctx, struct kvm_s
> */
> 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 (!skip_flush)
> + kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, mmu,
> + ctx->addr, ctx->level);
> }
>
> mm_ops->put_page(ctx->ptep);
> @@ -1015,7 +1018,7 @@ 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_put_pte(ctx, mmu, mm_ops, false);
>
> if (need_flush && mm_ops->dcache_clean_inval_poc)
> mm_ops->dcache_clean_inval_poc(kvm_pte_follow(ctx->old, mm_ops),
> --
> 2.40.0.634.g4ca3ef3211-goog
>
--
Thanks,
Oliver
