From: Shaoqin Huang <shahuang@redhat.com>
To: Ricardo Koller <ricarkol@google.com>,
pbonzini@redhat.com, maz@kernel.org, oupton@google.com,
yuzenghui@huawei.com, dmatlack@google.com
Cc: kvm@vger.kernel.org, kvmarm@lists.linux.dev, qperret@google.com,
catalin.marinas@arm.com, andrew.jones@linux.dev,
seanjc@google.com, alexandru.elisei@arm.com,
suzuki.poulose@arm.com, eric.auger@redhat.com, gshan@redhat.com,
reijiw@google.com, rananta@google.com, bgardon@google.com,
ricarkol@gmail.com
Subject: Re: [PATCH v4 03/12] KVM: arm64: Add helper for creating unlinked stage2 subtrees
Date: Mon, 20 Feb 2023 14:45:33 +0800 [thread overview]
Message-ID: <be032357-1af2-f910-276f-ed492b287784@redhat.com> (raw)
In-Reply-To: <20230218032314.635829-4-ricarkol@google.com>
Hi Ricardo,
On 2/18/23 11:23, Ricardo Koller wrote:
> Add a stage2 helper, kvm_pgtable_stage2_create_unlinked(), for
> creating unlinked tables (which is the opposite of
> kvm_pgtable_stage2_free_unlinked()). Creating an unlinked table is
> useful for splitting PMD and PUD blocks into subtrees of PAGE_SIZE
> PTEs. For example, a PUD can be split into PAGE_SIZE PTEs by first
> creating a fully populated tree, and then use it to replace the PUD in
> a single step. This will be used in a subsequent commit for eager
> huge-page splitting (a dirty-logging optimization).
>
> No functional change intended. This new function will be used in a
> subsequent commit.
>
> Signed-off-by: Ricardo Koller <ricarkol@google.com>
> ---
> arch/arm64/include/asm/kvm_pgtable.h | 28 +++++++++++++++++
> arch/arm64/kvm/hyp/pgtable.c | 46 ++++++++++++++++++++++++++++
> 2 files changed, 74 insertions(+)
>
> diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h
> index dcd3aafd3e6c..b8cde914cca9 100644
> --- a/arch/arm64/include/asm/kvm_pgtable.h
> +++ b/arch/arm64/include/asm/kvm_pgtable.h
> @@ -460,6 +460,34 @@ void kvm_pgtable_stage2_destroy(struct kvm_pgtable *pgt);
> */
> void kvm_pgtable_stage2_free_unlinked(struct kvm_pgtable_mm_ops *mm_ops, void *pgtable, u32 level);
>
> +/**
> + * kvm_pgtable_stage2_create_unlinked() - Create an unlinked stage-2 paging structure.
> + * @pgt: Page-table structure initialised by kvm_pgtable_stage2_init*().
> + * @phys: Physical address of the memory to map.
> + * @level: Starting level of the stage-2 paging structure to be created.
> + * @prot: Permissions and attributes for the mapping.
> + * @mc: Cache of pre-allocated and zeroed memory from which to allocate
> + * page-table pages.
> + * @force_pte: Force mappings to PAGE_SIZE granularity.
> + *
> + * Create an unlinked page-table tree under @new. If @force_pte is
> + * true or @level is 2 (the PMD level), then the tree is mapped up to
> + * the PAGE_SIZE leaf PTE; the tree is mapped up one level otherwise.
> + * This new page-table tree is not reachable (i.e., it is unlinked)
> + * from the root pgd and it's therefore unreachableby the hardware
> + * page-table walker. No TLB invalidation or CMOs are performed.
> + *
> + * If device attributes are not explicitly requested in @prot, then the
> + * mapping will be normal, cacheable.
> + *
> + * Return: The fully populated (unlinked) stage-2 paging structure, or
> + * an ERR_PTR(error) on failure.
> + */
> +kvm_pte_t *kvm_pgtable_stage2_create_unlinked(struct kvm_pgtable *pgt,
> + u64 phys, u32 level,
> + enum kvm_pgtable_prot prot,
> + void *mc, bool force_pte);
> +
> /**
> * kvm_pgtable_stage2_map() - Install a mapping in a guest stage-2 page-table.
> * @pgt: Page-table structure initialised by kvm_pgtable_stage2_init*().
> diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
> index 0a5ef9288371..80f2965ab0fe 100644
> --- a/arch/arm64/kvm/hyp/pgtable.c
> +++ b/arch/arm64/kvm/hyp/pgtable.c
> @@ -1181,6 +1181,52 @@ int kvm_pgtable_stage2_flush(struct kvm_pgtable *pgt, u64 addr, u64 size)
> return kvm_pgtable_walk(pgt, addr, size, &walker);
> }
>
> +kvm_pte_t *kvm_pgtable_stage2_create_unlinked(struct kvm_pgtable *pgt,
> + u64 phys, u32 level,
> + enum kvm_pgtable_prot prot,
> + void *mc, bool force_pte)
> +{
> + struct stage2_map_data map_data = {
> + .phys = phys,
> + .mmu = pgt->mmu,
> + .memcache = mc,
> + .force_pte = force_pte,
> + };
> + struct kvm_pgtable_walker walker = {
> + .cb = stage2_map_walker,
> + .flags = KVM_PGTABLE_WALK_LEAF |
> + KVM_PGTABLE_WALK_SKIP_BBM |
> + KVM_PGTABLE_WALK_SKIP_CMO,
> + .arg = &map_data,
> + };
> + /* .addr (the IPA) is irrelevant for a removed table */
for an unlinked table.
> + struct kvm_pgtable_walk_data data = {
> + .walker = &walker,
> + .addr = 0,
> + .end = kvm_granule_size(level),
> + };
> + struct kvm_pgtable_mm_ops *mm_ops = pgt->mm_ops;
> + kvm_pte_t *pgtable;
> + int ret;
> +
> + ret = stage2_set_prot_attr(pgt, prot, &map_data.attr);
> + if (ret)
> + return ERR_PTR(ret);
> +
> + pgtable = mm_ops->zalloc_page(mc);
> + if (!pgtable)
> + return ERR_PTR(-ENOMEM);
> +
> + ret = __kvm_pgtable_walk(&data, mm_ops, (kvm_pteref_t)pgtable,
> + level + 1);
> + if (ret) {
> + kvm_pgtable_stage2_free_unlinked(mm_ops, pgtable, level);
> + mm_ops->put_page(pgtable);
> + return ERR_PTR(ret);
> + }
> +
> + return pgtable;
> +}
>
> int __kvm_pgtable_stage2_init(struct kvm_pgtable *pgt, struct kvm_s2_mmu *mmu,
> struct kvm_pgtable_mm_ops *mm_ops,
--
Regards,
Shaoqin
next prev parent reply other threads:[~2023-02-20 6:45 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-18 3:23 [PATCH v4 00/12] Implement Eager Page Splitting for ARM Ricardo Koller
2023-02-18 3:23 ` [PATCH v4 01/12] KVM: arm64: Add KVM_PGTABLE_WALK ctx->flags for skipping BBM and CMO Ricardo Koller
2023-02-18 3:23 ` [PATCH v4 02/12] KVM: arm64: Rename free_unlinked to free_removed Ricardo Koller
2023-02-18 3:23 ` [PATCH v4 03/12] KVM: arm64: Add helper for creating unlinked stage2 subtrees Ricardo Koller
2023-02-20 6:35 ` Shaoqin Huang
2023-03-01 20:10 ` Ricardo Koller
2023-02-20 6:45 ` Shaoqin Huang [this message]
2023-02-18 3:23 ` [PATCH v4 04/12] KVM: arm64: Add kvm_pgtable_stage2_split() Ricardo Koller
2023-02-18 3:28 ` Ricardo Koller
2023-02-20 7:08 ` Shaoqin Huang
2023-03-01 20:09 ` Ricardo Koller
2023-02-18 3:23 ` [PATCH v4 05/12] KVM: arm64: Refactor kvm_arch_commit_memory_region() Ricardo Koller
2023-02-18 3:23 ` [PATCH v4 06/12] KVM: arm64: Add kvm_uninit_stage2_mmu() Ricardo Koller
2023-02-18 3:23 ` [PATCH v4 07/12] KVM: arm64: Export kvm_are_all_memslots_empty() Ricardo Koller
2023-02-18 3:23 ` [PATCH v4 08/12] KVM: arm64: Add KVM_CAP_ARM_EAGER_SPLIT_CHUNK_SIZE Ricardo Koller
2023-02-18 3:23 ` [PATCH v4 09/12] KVM: arm64: Split huge pages when dirty logging is enabled Ricardo Koller
2023-02-18 3:23 ` [PATCH v4 10/12] KVM: arm64: Open-code kvm_mmu_write_protect_pt_masked() Ricardo Koller
2023-02-18 3:23 ` [PATCH v4 11/12] KVM: arm64: Split huge pages during KVM_CLEAR_DIRTY_LOG Ricardo Koller
2023-02-18 3:23 ` [PATCH v4 12/12] KVM: arm64: Use local TLBI on permission relaxation Ricardo Koller
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