From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-12.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0A028C433DF for ; Tue, 18 Aug 2020 13:28:42 +0000 (UTC) Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by mail.kernel.org (Postfix) with ESMTP id B4C2A207FF for ; Tue, 18 Aug 2020 13:28:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="zwv7HIDK" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B4C2A207FF Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvmarm-bounces@lists.cs.columbia.edu Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 6C2844BE03; Tue, 18 Aug 2020 09:28:41 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Authentication-Results: mm01.cs.columbia.edu (amavisd-new); dkim=softfail (fail, message has been altered) header.i=@kernel.org Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id exQSP0q4R4NN; Tue, 18 Aug 2020 09:28:39 -0400 (EDT) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 93DC34BD17; Tue, 18 Aug 2020 09:28:39 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 1A5FE4BD04 for ; Tue, 18 Aug 2020 09:28:38 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id W+qjrBTHIwtV for ; Tue, 18 Aug 2020 09:28:36 -0400 (EDT) Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by mm01.cs.columbia.edu (Postfix) with ESMTPS id BD3794BA0F for ; Tue, 18 Aug 2020 09:28:35 -0400 (EDT) Received: from localhost.localdomain (236.31.169.217.in-addr.arpa [217.169.31.236]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 4A3A7207DA; Tue, 18 Aug 2020 13:28:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597757315; bh=64ok2O7xOshYLlj88/t9cK/lh+ZTBVXuqyv7d21nxDg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=zwv7HIDKT18D3k2GsSqEaXHq+n+UtWFcqjkdG9k1JJZtTHNZg2ebL31lVZUv8388O GPm9g5aJ0yrxzPRA+/JiPTu8jXr1BD0mue5EeoGHjit6Fn6T8AR66qkJAhFA6LOg2x Rg3jSknztmNeNiC59GxqMxnK7pbWfS+hk66y8hNc= From: Will Deacon To: kvmarm@lists.cs.columbia.edu Subject: [PATCH v2 03/22] KVM: arm64: Add stand-alone page-table walker infrastructure Date: Tue, 18 Aug 2020 14:27:59 +0100 Message-Id: <20200818132818.16065-4-will@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200818132818.16065-1-will@kernel.org> References: <20200818132818.16065-1-will@kernel.org> MIME-Version: 1.0 Cc: kernel-team@android.com, Marc Zyngier , Catalin Marinas , Will Deacon , linux-arm-kernel@lists.infradead.org X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu The KVM page-table code is intricately tied into the kernel page-table code and re-uses the pte/pmd/pud/p4d/pgd macros directly in an attempt to reduce code duplication. Unfortunately, the reality is that there is an awful lot of code required to make this work, and at the end of the day you're limited to creating page-tables with the same configuration as the host kernel. Furthermore, lifting the page-table code to run directly at EL2 on a non-VHE system (as we plan to to do in future patches) is practically impossible due to the number of dependencies it has on the core kernel. Introduce a framework for walking Armv8 page-tables configured independently from the host kernel. Cc: Marc Zyngier Cc: Quentin Perret Signed-off-by: Will Deacon --- arch/arm64/include/asm/kvm_pgtable.h | 101 ++++++++++ arch/arm64/kvm/hyp/Makefile | 2 +- arch/arm64/kvm/hyp/pgtable.c | 290 +++++++++++++++++++++++++++ 3 files changed, 392 insertions(+), 1 deletion(-) create mode 100644 arch/arm64/include/asm/kvm_pgtable.h create mode 100644 arch/arm64/kvm/hyp/pgtable.c diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h new file mode 100644 index 000000000000..51ccbbb0efae --- /dev/null +++ b/arch/arm64/include/asm/kvm_pgtable.h @@ -0,0 +1,101 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2020 Google LLC + * Author: Will Deacon + */ + +#ifndef __ARM64_KVM_PGTABLE_H__ +#define __ARM64_KVM_PGTABLE_H__ + +#include +#include +#include + +typedef u64 kvm_pte_t; + +/** + * struct kvm_pgtable - KVM page-table. + * @ia_bits: Maximum input address size, in bits. + * @start_level: Level at which the page-table walk starts. + * @pgd: Pointer to the first top-level entry of the page-table. + * @mmu: Stage-2 KVM MMU struct. Unused for stage-1 page-tables. + */ +struct kvm_pgtable { + u32 ia_bits; + u32 start_level; + kvm_pte_t *pgd; + + /* Stage-2 only */ + struct kvm_s2_mmu *mmu; +}; + +/** + * enum kvm_pgtable_prot - Page-table permissions and attributes. + * @KVM_PGTABLE_PROT_R: Read permission. + * @KVM_PGTABLE_PROT_W: Write permission. + * @KVM_PGTABLE_PROT_X: Execute permission. + * @KVM_PGTABLE_PROT_DEVICE: Device attributes. + */ +enum kvm_pgtable_prot { + KVM_PGTABLE_PROT_R = BIT(0), + KVM_PGTABLE_PROT_W = BIT(1), + KVM_PGTABLE_PROT_X = BIT(2), + + KVM_PGTABLE_PROT_DEVICE = BIT(3), +}; + +/** + * enum kvm_pgtable_walk_flags - Flags to control a depth-first page-table walk. + * @KVM_PGTABLE_WALK_LEAF: Visit leaf entries, including invalid + * entries. + * @KVM_PGTABLE_WALK_TABLE_PRE: Visit table entries before their + * children. + * @KVM_PGTABLE_WALK_TABLE_POST: Visit table entries after their + * children. + */ +enum kvm_pgtable_walk_flags { + KVM_PGTABLE_WALK_LEAF = BIT(0), + KVM_PGTABLE_WALK_TABLE_PRE = BIT(1), + KVM_PGTABLE_WALK_TABLE_POST = BIT(2), +}; + +typedef int (*kvm_pgtable_visitor_fn_t)(u64 addr, u64 end, u32 level, + kvm_pte_t *ptep, + enum kvm_pgtable_walk_flags flag, + void * const arg); + +/** + * struct kvm_pgtable_walker - Hook into a page-table walk. + * @cb: Callback function to invoke during the walk. + * @arg: Argument passed to the callback function. + * @flags: Bitwise-OR of flags to identify the entry types on which to + * invoke the callback function. + */ +struct kvm_pgtable_walker { + const kvm_pgtable_visitor_fn_t cb; + void * const arg; + const enum kvm_pgtable_walk_flags flags; +}; + +/** + * kvm_pgtable_walk() - Walk a page-table. + * @pgt: Page-table structure initialised by kvm_pgtable_*_init(). + * @addr: Input address for the start of the walk. + * @size: Size of the range to walk. + * @walker: Walker callback description. + * + * The walker will walk the page-table entries corresponding to the input + * address range specified, visiting entries according to the walker flags. + * Invalid entries are treated as leaf entries. Leaf entries are reloaded + * after invoking the walker callback, allowing the walker to descend into + * a newly installed table. + * + * Returning a negative error code from the walker callback function will + * terminate the walk immediately with the same error code. + * + * Return: 0 on success, negative error code on failure. + */ +int kvm_pgtable_walk(struct kvm_pgtable *pgt, u64 addr, u64 size, + struct kvm_pgtable_walker *walker); + +#endif /* __ARM64_KVM_PGTABLE_H__ */ diff --git a/arch/arm64/kvm/hyp/Makefile b/arch/arm64/kvm/hyp/Makefile index f54f0e89a71c..607b8a898826 100644 --- a/arch/arm64/kvm/hyp/Makefile +++ b/arch/arm64/kvm/hyp/Makefile @@ -10,5 +10,5 @@ subdir-ccflags-y := -I$(incdir) \ -DDISABLE_BRANCH_PROFILING \ $(DISABLE_STACKLEAK_PLUGIN) -obj-$(CONFIG_KVM) += vhe/ nvhe/ +obj-$(CONFIG_KVM) += vhe/ nvhe/ pgtable.o obj-$(CONFIG_KVM_INDIRECT_VECTORS) += smccc_wa.o diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c new file mode 100644 index 000000000000..462001bbe028 --- /dev/null +++ b/arch/arm64/kvm/hyp/pgtable.c @@ -0,0 +1,290 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Stand-alone page-table allocator for hyp stage-1 and guest stage-2. + * No bombay mix was harmed in the writing of this file. + * + * Copyright (C) 2020 Google LLC + * Author: Will Deacon + */ + +#include +#include + +#define KVM_PGTABLE_MAX_LEVELS 4U + +#define KVM_PTE_VALID BIT(0) + +#define KVM_PTE_TYPE BIT(1) +#define KVM_PTE_TYPE_BLOCK 0 +#define KVM_PTE_TYPE_PAGE 1 +#define KVM_PTE_TYPE_TABLE 1 + +#define KVM_PTE_ADDR_MASK GENMASK(47, PAGE_SHIFT) +#define KVM_PTE_ADDR_51_48 GENMASK(15, 12) + +#define KVM_PTE_LEAF_ATTR_LO GENMASK(11, 2) + +#define KVM_PTE_LEAF_ATTR_HI GENMASK(63, 51) + +struct kvm_pgtable_walk_data { + struct kvm_pgtable *pgt; + struct kvm_pgtable_walker *walker; + + u64 addr; + u64 end; +}; + +static u64 kvm_granule_shift(u32 level) +{ + return (KVM_PGTABLE_MAX_LEVELS - level) * (PAGE_SHIFT - 3) + 3; +} + +static u64 kvm_granule_size(u32 level) +{ + return BIT(kvm_granule_shift(level)); +} + +static bool kvm_block_mapping_supported(u64 addr, u64 end, u64 phys, u32 level) +{ + u64 granule = kvm_granule_size(level); + + /* + * Reject invalid block mappings and don't bother with 4TB mappings for + * 52-bit PAs. + */ + if (level == 0 || (PAGE_SIZE != SZ_4K && level == 1)) + return false; + + if (granule > (end - addr)) + return false; + + return IS_ALIGNED(addr, granule) && IS_ALIGNED(phys, granule); +} + +static u32 kvm_start_level(u64 ia_bits) +{ + u64 levels = DIV_ROUND_UP(ia_bits - PAGE_SHIFT, PAGE_SHIFT - 3); + return KVM_PGTABLE_MAX_LEVELS - levels; +} + +static u32 kvm_pgtable_idx(struct kvm_pgtable_walk_data *data, u32 level) +{ + u64 shift = kvm_granule_shift(level); + u64 mask = BIT(PAGE_SHIFT - 3) - 1; + + return (data->addr >> shift) & mask; +} + +static u32 __kvm_pgd_page_idx(struct kvm_pgtable *pgt, u64 addr) +{ + u64 shift = kvm_granule_shift(pgt->start_level - 1); /* May underflow */ + u64 mask = BIT(pgt->ia_bits) - 1; + + return (addr & mask) >> shift; +} + +static u32 kvm_pgd_page_idx(struct kvm_pgtable_walk_data *data) +{ + return __kvm_pgd_page_idx(data->pgt, data->addr); +} + +static u32 kvm_pgd_pages(u32 ia_bits, u32 start_level) +{ + struct kvm_pgtable pgt = { + .ia_bits = ia_bits, + .start_level = start_level, + }; + + return __kvm_pgd_page_idx(&pgt, -1ULL) + 1; +} + +static bool kvm_pte_valid(kvm_pte_t pte) +{ + return pte & KVM_PTE_VALID; +} + +static bool kvm_pte_table(kvm_pte_t pte, u32 level) +{ + if (level == KVM_PGTABLE_MAX_LEVELS - 1) + return false; + + if (!kvm_pte_valid(pte)) + return false; + + return FIELD_GET(KVM_PTE_TYPE, pte) == KVM_PTE_TYPE_TABLE; +} + +static u64 kvm_pte_to_phys(kvm_pte_t pte) +{ + u64 pa = pte & KVM_PTE_ADDR_MASK; + + if (PAGE_SHIFT == 16) + pa |= FIELD_GET(KVM_PTE_ADDR_51_48, pte) << 48; + + return pa; +} + +static kvm_pte_t kvm_phys_to_pte(u64 pa) +{ + kvm_pte_t pte = pa & KVM_PTE_ADDR_MASK; + + if (PAGE_SHIFT == 16) + pte |= FIELD_PREP(KVM_PTE_ADDR_51_48, pa >> 48); + + return pte; +} + +static kvm_pte_t *kvm_pte_follow(kvm_pte_t pte) +{ + return __va(kvm_pte_to_phys(pte)); +} + +static void kvm_set_invalid_pte(kvm_pte_t *ptep) +{ + kvm_pte_t pte = 0; + WRITE_ONCE(*ptep, pte); +} + +static void kvm_set_table_pte(kvm_pte_t *ptep, kvm_pte_t *childp) +{ + kvm_pte_t old = *ptep, pte = kvm_phys_to_pte(__pa(childp)); + + pte |= FIELD_PREP(KVM_PTE_TYPE, KVM_PTE_TYPE_TABLE); + pte |= KVM_PTE_VALID; + + WARN_ON(kvm_pte_valid(old)); + smp_store_release(ptep, pte); +} + +static bool kvm_set_valid_leaf_pte(kvm_pte_t *ptep, u64 pa, kvm_pte_t attr, + u32 level) +{ + kvm_pte_t old = *ptep, pte = kvm_phys_to_pte(pa); + u64 type = (level == KVM_PGTABLE_MAX_LEVELS - 1) ? KVM_PTE_TYPE_PAGE : + KVM_PTE_TYPE_BLOCK; + + pte |= attr & (KVM_PTE_LEAF_ATTR_LO | KVM_PTE_LEAF_ATTR_HI); + pte |= FIELD_PREP(KVM_PTE_TYPE, type); + pte |= KVM_PTE_VALID; + + /* Tolerate KVM recreating the exact same mapping. */ + if (kvm_pte_valid(old)) + return old == pte; + + smp_store_release(ptep, pte); + return true; +} + +static int kvm_pgtable_visitor_cb(struct kvm_pgtable_walk_data *data, u64 addr, + u32 level, kvm_pte_t *ptep, + enum kvm_pgtable_walk_flags flag) +{ + struct kvm_pgtable_walker *walker = data->walker; + return walker->cb(addr, data->end, level, ptep, flag, walker->arg); +} + +static int __kvm_pgtable_walk(struct kvm_pgtable_walk_data *data, + kvm_pte_t *pgtable, u32 level); + +static inline int __kvm_pgtable_visit(struct kvm_pgtable_walk_data *data, + kvm_pte_t *ptep, u32 level) +{ + int ret = 0; + u64 addr = data->addr; + kvm_pte_t *childp, pte = *ptep; + bool table = kvm_pte_table(pte, level); + enum kvm_pgtable_walk_flags flags = data->walker->flags; + + if (table && (flags & KVM_PGTABLE_WALK_TABLE_PRE)) { + ret = kvm_pgtable_visitor_cb(data, addr, level, ptep, + KVM_PGTABLE_WALK_TABLE_PRE); + } + + if (!table && (flags & KVM_PGTABLE_WALK_LEAF)) { + ret = kvm_pgtable_visitor_cb(data, addr, level, ptep, + KVM_PGTABLE_WALK_LEAF); + pte = *ptep; + table = kvm_pte_table(pte, level); + } + + if (ret) + goto out; + + if (!table) { + data->addr += kvm_granule_size(level); + goto out; + } + + childp = kvm_pte_follow(pte); + ret = __kvm_pgtable_walk(data, childp, level + 1); + if (ret) + goto out; + + if (flags & KVM_PGTABLE_WALK_TABLE_POST) { + ret = kvm_pgtable_visitor_cb(data, addr, level, ptep, + KVM_PGTABLE_WALK_TABLE_POST); + } + +out: + return ret; +} + +static int __kvm_pgtable_walk(struct kvm_pgtable_walk_data *data, + kvm_pte_t *pgtable, u32 level) +{ + u32 idx; + int ret = 0; + + if (WARN_ON_ONCE(level >= KVM_PGTABLE_MAX_LEVELS)) + return -EINVAL; + + for (idx = kvm_pgtable_idx(data, level); idx < PTRS_PER_PTE; ++idx) { + kvm_pte_t *ptep = &pgtable[idx]; + + if (data->addr >= data->end) + break; + + ret = __kvm_pgtable_visit(data, ptep, level); + if (ret) + break; + } + + return ret; +} + +static int _kvm_pgtable_walk(struct kvm_pgtable_walk_data *data) +{ + u32 idx; + int ret = 0; + struct kvm_pgtable *pgt = data->pgt; + u64 limit = BIT(pgt->ia_bits); + + if (data->addr > limit || data->end > limit) + return -ERANGE; + + if (!pgt->pgd) + return -EINVAL; + + for (idx = kvm_pgd_page_idx(data); data->addr < data->end; ++idx) { + kvm_pte_t *ptep = &pgt->pgd[idx * PTRS_PER_PTE]; + + ret = __kvm_pgtable_walk(data, ptep, pgt->start_level); + if (ret) + break; + } + + return ret; +} + +int kvm_pgtable_walk(struct kvm_pgtable *pgt, u64 addr, u64 size, + struct kvm_pgtable_walker *walker) +{ + struct kvm_pgtable_walk_data walk_data = { + .pgt = pgt, + .addr = ALIGN_DOWN(addr, PAGE_SIZE), + .end = PAGE_ALIGN(walk_data.addr + size), + .walker = walker, + }; + + return _kvm_pgtable_walk(&walk_data); +} -- 2.28.0.220.ged08abb693-goog _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm