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[209.132.180.67]) by mx.google.com with ESMTP id r130-v6si14195434pgr.456.2018.09.17.03.43.17; Mon, 17 Sep 2018 03:43:33 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728414AbeIQQJm (ORCPT + 99 others); Mon, 17 Sep 2018 12:09:42 -0400 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:56564 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726676AbeIQQJl (ORCPT ); Mon, 17 Sep 2018 12:09:41 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 4904C1684; Mon, 17 Sep 2018 03:42:53 -0700 (PDT) Received: from en101.Emea.Arm.com (en101.emea.arm.com [10.4.13.23]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id C17F83F5BD; Mon, 17 Sep 2018 03:42:50 -0700 (PDT) From: Suzuki K Poulose To: linux-arm-kernel@lists.infradead.org Cc: kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, marc.zyngier@arm.com, cdall@kernel.org, eric.auger@redhat.com, pbonzini@redhat.com, rkrcmar@redhat.com, will.deacon@arm.com, catalin.marinas@arm.com, james.morse@arm.com, dave.martin@arm.com, julien.grall@arm.com, linux-kernel@vger.kernel.org, suzuki.poulose@arm.com Subject: [PATCH v5 11/18] kvm: arm64: Dynamic configuration of VTTBR mask Date: Mon, 17 Sep 2018 11:41:33 +0100 Message-Id: <20180917104144.19188-12-suzuki.poulose@arm.com> X-Mailer: git-send-email 2.19.0 In-Reply-To: <20180917104144.19188-1-suzuki.poulose@arm.com> References: <20180917104144.19188-1-suzuki.poulose@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On arm64 VTTBR_EL2:BADDR holds the base address for the stage2 translation table. The Arm ARM mandates that the bits BADDR[x-1:0] should be 0, where 'x' is defined for a given IPA Size and the number of levels for a translation granule size. It is defined using some magical constants. This patch is a reverse engineered implementation to calculate the 'x' at runtime for a given ipa and number of page table levels. See patch for more details. Cc: Marc Zyngier Cc: Christoffer Dall Signed-off-by: Suzuki K Poulose --- Changes since V3: - Update reference to latest ARM ARM and improve commentary --- arch/arm64/include/asm/kvm_arm.h | 63 +++++++++++++++++++++++++++++--- arch/arm64/include/asm/kvm_mmu.h | 25 ++++++++++++- 2 files changed, 81 insertions(+), 7 deletions(-) diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h index 14317b3a1820..3fb1d440be6e 100644 --- a/arch/arm64/include/asm/kvm_arm.h +++ b/arch/arm64/include/asm/kvm_arm.h @@ -123,7 +123,6 @@ #define VTCR_EL2_SL0_MASK (3 << VTCR_EL2_SL0_SHIFT) #define VTCR_EL2_SL0_LVL1 (1 << VTCR_EL2_SL0_SHIFT) #define VTCR_EL2_T0SZ_MASK 0x3f -#define VTCR_EL2_T0SZ_40B 24 #define VTCR_EL2_VS_SHIFT 19 #define VTCR_EL2_VS_8BIT (0 << VTCR_EL2_VS_SHIFT) #define VTCR_EL2_VS_16BIT (1 << VTCR_EL2_VS_SHIFT) @@ -140,11 +139,8 @@ * Note that when using 4K pages, we concatenate two first level page tables * together. With 16K pages, we concatenate 16 first level page tables. * - * The magic numbers used for VTTBR_X in this patch can be found in Tables - * D4-23 and D4-25 in ARM DDI 0487A.b. */ -#define VTCR_EL2_T0SZ_IPA VTCR_EL2_T0SZ_40B #define VTCR_EL2_COMMON_BITS (VTCR_EL2_SH0_INNER | VTCR_EL2_ORGN0_WBWA | \ VTCR_EL2_IRGN0_WBWA | VTCR_EL2_RES1) @@ -175,9 +171,64 @@ #endif #define VTCR_EL2_FLAGS (VTCR_EL2_COMMON_BITS | VTCR_EL2_TGRAN_FLAGS) -#define VTTBR_X (VTTBR_X_TGRAN_MAGIC - VTCR_EL2_T0SZ_IPA) +/* + * ARM VMSAv8-64 defines an algorithm for finding the translation table + * descriptors in section D4.2.8 in ARM DDI 0487C.a. + * + * The algorithm defines the expectations on the BaseAddress (for the page + * table) bits resolved at each level based on the page size, entry level + * and T0SZ. The variable "x" in the algorithm also affects the VTTBR:BADDR + * for stage2 page table. + * + * The value of "x" is calculated as : + * x = Magic_N - T0SZ + * + * where Magic_N is an integer depending on the page size and the entry + * level of the page table as below: + * + * -------------------------------------------- + * | Entry level | 4K 16K 64K | + * -------------------------------------------- + * | Level: 0 (4 levels) | 28 | - | - | + * -------------------------------------------- + * | Level: 1 (3 levels) | 37 | 31 | 25 | + * -------------------------------------------- + * | Level: 2 (2 levels) | 46 | 42 | 38 | + * -------------------------------------------- + * | Level: 3 (1 level) | - | 53 | 51 | + * -------------------------------------------- + * + * We have a magic formula for the Magic_N below: + * + * Magic_N(PAGE_SIZE, Level) = 64 - ((PAGE_SHIFT - 3) * Number_of_levels) + * + * where Number_of_levels = (4 - Level). We are only interested in the + * value for Entry_Level for the stage2 page table. + * + * So, given that T0SZ = (64 - IPA_SHIFT), we can compute 'x' as follows: + * + * x = (64 - ((PAGE_SHIFT - 3) * Number_of_levels)) - (64 - IPA_SHIFT) + * = IPA_SHIFT - ((PAGE_SHIFT - 3) * Number of levels) + * + * Here is one way to explain the Magic Formula: + * + * x = log2(Size_of_Entry_Level_Table) + * + * Since, we can resolve (PAGE_SHIFT - 3) bits at each level, and another + * PAGE_SHIFT bits in the PTE, we have : + * + * Bits_Entry_level = IPA_SHIFT - ((PAGE_SHIFT - 3) * (n - 1) + PAGE_SHIFT) + * = IPA_SHIFT - (PAGE_SHIFT - 3) * n - 3 + * where n = number of levels, and since each pointer is 8bytes, we have: + * + * x = Bits_Entry_Level + 3 + * = IPA_SHIFT - (PAGE_SHIFT - 3) * n + * + * The only constraint here is that, we have to find the number of page table + * levels for a given IPA size (which we do, see stage2_pt_levels()) + */ +#define ARM64_VTTBR_X(ipa, levels) ((ipa) - ((levels) * (PAGE_SHIFT - 3))) -#define VTTBR_BADDR_MASK (((UL(1) << (PHYS_MASK_SHIFT - VTTBR_X)) - 1) << VTTBR_X) #define VTTBR_VMID_SHIFT (UL(48)) #define VTTBR_VMID_MASK(size) (_AT(u64, (1 << size) - 1) << VTTBR_VMID_SHIFT) diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h index 7342d2c51773..ac3ca9690bad 100644 --- a/arch/arm64/include/asm/kvm_mmu.h +++ b/arch/arm64/include/asm/kvm_mmu.h @@ -145,7 +145,6 @@ static inline unsigned long __kern_hyp_va(unsigned long v) #define kvm_phys_shift(kvm) KVM_PHYS_SHIFT #define kvm_phys_size(kvm) (_AC(1, ULL) << kvm_phys_shift(kvm)) #define kvm_phys_mask(kvm) (kvm_phys_size(kvm) - _AC(1, ULL)) -#define kvm_vttbr_baddr_mask(kvm) VTTBR_BADDR_MASK static inline bool kvm_page_empty(void *ptr) { @@ -520,5 +519,29 @@ static inline int hyp_map_aux_data(void) #define kvm_phys_to_vttbr(addr) phys_to_ttbr(addr) +/* + * Get the magic number 'x' for VTTBR:BADDR of this KVM instance. + * With v8.2 LVA extensions, 'x' should be a minimum of 6 with + * 52bit IPS. + */ +static inline int arm64_vttbr_x(u32 ipa_shift, u32 levels) +{ + int x = ARM64_VTTBR_X(ipa_shift, levels); + + return (IS_ENABLED(CONFIG_ARM64_PA_BITS_52) && x < 6) ? 6 : x; +} + +static inline u64 vttbr_baddr_mask(u32 ipa_shift, u32 levels) +{ + unsigned int x = arm64_vttbr_x(ipa_shift, levels); + + return GENMASK_ULL(PHYS_MASK_SHIFT - 1, x); +} + +static inline u64 kvm_vttbr_baddr_mask(struct kvm *kvm) +{ + return vttbr_baddr_mask(kvm_phys_shift(kvm), kvm_stage2_levels(kvm)); +} + #endif /* __ASSEMBLY__ */ #endif /* __ARM64_KVM_MMU_H__ */ -- 2.19.0