From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-yb1-f201.google.com (mail-yb1-f201.google.com [209.85.219.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CE462391 for ; Tue, 7 Mar 2023 03:46:05 +0000 (UTC) Received: by mail-yb1-f201.google.com with SMTP id o3-20020a257303000000b00a131264017aso12879162ybc.20 for ; Mon, 06 Mar 2023 19:46:05 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; t=1678160765; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=LorRr0tSpPV/HiTkZVHPusAZFDDTrzxf4iYCwZK3qzw=; b=I4a8SUlrLvvojeYvcmMiC2zUZqQybK5hGvCBgIlFENN8OH8+w84QrNNMzLTtRLSVEb WB3rMuNT6MTPDlJMFlx+wdo3vij0qvyB70IktGwAjhfI2pwmEGOfb04kkUfIahgMOaEz 8KdaZzF/EkLndc/l8jvYzuDJ1cbuyHrP3M4TgOS87Aq+CkknLjsq2GitR7FI1i1qtGfF FB7wRha45vW03qg9Aj3CNRg/vgnwf0ALVefC0xV/SnGKua9CbSIsx+Uxd4ifh3YMpaH3 +YQVnukhAMoOQeAKxtkmKr7bf4RvZH99JIUE0comNzweFbr97OlTkFal3jvJpsmwDu5+ Ef/A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1678160765; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=LorRr0tSpPV/HiTkZVHPusAZFDDTrzxf4iYCwZK3qzw=; b=N+RaZf8WpfELG9ABHlP8ROMrZbBlaw179lC/krll0/x8CrSpkTNTx2HI2gdfU4Hinz RH86NhBSmC5oGSkUk0Mqv0ZuGtjSSRrw4AShWm3EtjdMGngt0SZgozOcFq9S4QGZWbkB FtT3ThwXLjBp9CTItxmuTgc8rdSEBoK8TP+4h46rj2ew2sJEtmsZJJk5Qf+Mr8H/2g4a uAEIfQxoPC71xnblk2ahYVqCu7ZmPzhUaZL5vxd9Tn8QZZUw3izfTZvqEdwAfUovoDSP IxrJxqX9mPgCfF0B2kWfZhSGjRuS7STeAz855p0occK6B6dQ6gSr+aBHL8kqeMKle43C bseQ== X-Gm-Message-State: AO0yUKWD7t3+eim2oHBpHmaMo0JaA5SUHYp+YjN7oQzr2sZaWQXFRUjq orbZOo9vR4/08uIfmUAJZ2gUYdxqtj2tsw== X-Google-Smtp-Source: AK7set/nYKOurqX7+27yzQnB5T3x7aiLZyUfSTSEnkwHX6VlUk/ecQNoH6NrmKl7u68atLnyiVZm6gc+BTPPFg== X-Received: from ricarkol4.c.googlers.com ([fda3:e722:ac3:cc00:20:ed76:c0a8:1248]) (user=ricarkol job=sendgmr) by 2002:a5b:70c:0:b0:a30:38fb:a0b8 with SMTP id g12-20020a5b070c000000b00a3038fba0b8mr7892121ybq.9.1678160764841; Mon, 06 Mar 2023 19:46:04 -0800 (PST) Date: Tue, 7 Mar 2023 03:45:47 +0000 In-Reply-To: <20230307034555.39733-1-ricarkol@google.com> Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20230307034555.39733-1-ricarkol@google.com> X-Mailer: git-send-email 2.40.0.rc0.216.gc4246ad0f0-goog Message-ID: <20230307034555.39733-5-ricarkol@google.com> Subject: [PATCH v6 04/12] KVM: arm64: Add kvm_pgtable_stage2_split() From: Ricardo Koller To: 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, Ricardo Koller , Shaoqin Huang Content-Type: text/plain; charset="UTF-8" Add a new stage2 function, kvm_pgtable_stage2_split(), for splitting a range of huge pages. This will be used for eager-splitting huge pages into PAGE_SIZE pages. The goal is to avoid having to split huge pages on write-protection faults, and instead use this function to do it ahead of time for large ranges (e.g., all guest memory in 1G chunks at a time). No functional change intended. This new function will be used in a subsequent commit. Signed-off-by: Ricardo Koller Reviewed-by: Shaoqin Huang --- arch/arm64/include/asm/kvm_pgtable.h | 30 +++++++ arch/arm64/kvm/hyp/pgtable.c | 113 +++++++++++++++++++++++++++ 2 files changed, 143 insertions(+) diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h index b7b3fc0fa7a5..40e323a718fc 100644 --- a/arch/arm64/include/asm/kvm_pgtable.h +++ b/arch/arm64/include/asm/kvm_pgtable.h @@ -665,6 +665,36 @@ bool kvm_pgtable_stage2_is_young(struct kvm_pgtable *pgt, u64 addr); */ int kvm_pgtable_stage2_flush(struct kvm_pgtable *pgt, u64 addr, u64 size); +/** + * kvm_pgtable_stage2_split() - Split a range of huge pages into leaf PTEs pointing + * to PAGE_SIZE guest pages. + * @pgt: Page-table structure initialised by kvm_pgtable_stage2_init(). + * @addr: Intermediate physical address from which to split. + * @size: Size of the range. + * @mc: Cache of pre-allocated and zeroed memory from which to allocate + * page-table pages. + * @mc_capacity: Number of pages in @mc. + * + * @addr and the end (@addr + @size) are effectively aligned down and up to + * the top level huge-page block size. This is an example using 1GB + * huge-pages and 4KB granules. + * + * [---input range---] + * : : + * [--1G block pte--][--1G block pte--][--1G block pte--][--1G block pte--] + * : : + * [--2MB--][--2MB--][--2MB--][--2MB--] + * : : + * [ ][ ][:][ ][ ][ ][ ][ ][:][ ][ ][ ] + * : : + * + * Return: 0 on success, negative error code on failure. Note that + * kvm_pgtable_stage2_split() is best effort: it tries to break as many + * blocks in the input range as allowed by @mc_capacity. + */ +int kvm_pgtable_stage2_split(struct kvm_pgtable *pgt, u64 addr, u64 size, + void *mc, u64 mc_capacity); + /** * kvm_pgtable_walk() - Walk a page-table. * @pgt: Page-table structure initialised by kvm_pgtable_*_init(). diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c index 6bdfcb671b32..3149b98d1701 100644 --- a/arch/arm64/kvm/hyp/pgtable.c +++ b/arch/arm64/kvm/hyp/pgtable.c @@ -1259,6 +1259,119 @@ kvm_pte_t *kvm_pgtable_stage2_create_unlinked(struct kvm_pgtable *pgt, return pgtable; } +struct stage2_split_data { + struct kvm_s2_mmu *mmu; + void *memcache; + u64 mc_capacity; +}; + +/* + * Get the number of page-tables needed to replace a block with a + * fully populated tree, up to the PTE level, at particular level. + */ +static inline int stage2_block_get_nr_page_tables(u32 level) +{ + if (WARN_ON_ONCE(level < KVM_PGTABLE_MIN_BLOCK_LEVEL || + level >= KVM_PGTABLE_MAX_LEVELS)) + return -EINVAL; + + switch (level) { + case 1: + return PTRS_PER_PTE + 1; + case 2: + return 1; + case 3: + return 0; + default: + return -EINVAL; + }; +} + +static int stage2_split_walker(const struct kvm_pgtable_visit_ctx *ctx, + enum kvm_pgtable_walk_flags visit) +{ + struct kvm_pgtable_mm_ops *mm_ops = ctx->mm_ops; + struct stage2_split_data *data = ctx->arg; + kvm_pte_t pte = ctx->old, new, *childp; + enum kvm_pgtable_prot prot; + void *mc = data->memcache; + u32 level = ctx->level; + bool force_pte; + int nr_pages; + u64 phys; + + /* No huge-pages exist at the last level */ + if (level == KVM_PGTABLE_MAX_LEVELS - 1) + return 0; + + /* We only split valid block mappings */ + if (!kvm_pte_valid(pte)) + return 0; + + nr_pages = stage2_block_get_nr_page_tables(level); + if (nr_pages < 0) + return nr_pages; + + if (data->mc_capacity >= nr_pages) { + /* Build a tree mapped down to the PTE granularity. */ + force_pte = true; + } else { + /* + * Don't force PTEs. This requires a single page of PMDs at the + * PUD level, or a single page of PTEs at the PMD level. If we + * are at the PUD level, the PTEs will be created recursively. + */ + force_pte = false; + nr_pages = 1; + } + + if (data->mc_capacity < nr_pages) + return -ENOMEM; + + phys = kvm_pte_to_phys(pte); + prot = kvm_pgtable_stage2_pte_prot(pte); + + childp = kvm_pgtable_stage2_create_unlinked(data->mmu->pgt, phys, + level, prot, mc, force_pte); + if (IS_ERR(childp)) + return PTR_ERR(childp); + + if (!stage2_try_break_pte(ctx, data->mmu)) { + kvm_pgtable_stage2_free_unlinked(mm_ops, childp, level); + mm_ops->put_page(childp); + return -EAGAIN; + } + + /* + * Note, the contents of the page table are guaranteed to be made + * visible before the new PTE is assigned because stage2_make_pte() + * writes the PTE using smp_store_release(). + */ + new = kvm_init_table_pte(childp, mm_ops); + stage2_make_pte(ctx, new); + dsb(ishst); + data->mc_capacity -= nr_pages; + return 0; +} + +int kvm_pgtable_stage2_split(struct kvm_pgtable *pgt, u64 addr, u64 size, + void *mc, u64 mc_capacity) +{ + struct stage2_split_data split_data = { + .mmu = pgt->mmu, + .memcache = mc, + .mc_capacity = mc_capacity, + }; + + struct kvm_pgtable_walker walker = { + .cb = stage2_split_walker, + .flags = KVM_PGTABLE_WALK_LEAF, + .arg = &split_data, + }; + + return kvm_pgtable_walk(pgt, addr, size, &walker); +} + int __kvm_pgtable_stage2_init(struct kvm_pgtable *pgt, struct kvm_s2_mmu *mmu, struct kvm_pgtable_mm_ops *mm_ops, enum kvm_pgtable_stage2_flags flags, -- 2.40.0.rc0.216.gc4246ad0f0-goog