From patchwork Fri May 6 14:08:44 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nikos Nikoleris X-Patchwork-Id: 12841225 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4A81CC433F5 for ; Fri, 6 May 2022 14:09:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1442017AbiEFONF (ORCPT ); Fri, 6 May 2022 10:13:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34686 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1442029AbiEFOM7 (ORCPT ); Fri, 6 May 2022 10:12:59 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 81748674D7 for ; Fri, 6 May 2022 07:09:16 -0700 (PDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 373A31595; Fri, 6 May 2022 07:09:16 -0700 (PDT) Received: from godel.lab.cambridge.arm.com (godel.lab.cambridge.arm.com [10.7.66.42]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 47BAC3F885; Fri, 6 May 2022 07:09:15 -0700 (PDT) From: Nikos Nikoleris To: Andrew Jones Cc: jade.alglave@arm.com, alexandru.elisei@arm.com, Nikos Nikoleris , kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu Subject: [kvm-unit-tests PATCH 12/23] arm/arm64: mmu_disable: Clean and invalidate before disabling Date: Fri, 6 May 2022 15:08:44 +0100 Message-Id: <20220506140855.353337-13-nikos.nikoleris@arm.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220506140855.353337-1-nikos.nikoleris@arm.com> References: <20220506140855.353337-1-nikos.nikoleris@arm.com> MIME-Version: 1.0 X-ARM-No-Footer: FoSSMail Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org From: Andrew Jones The commit message of commit 410b3bf09e76 ("arm/arm64: Perform dcache clean + invalidate after turning MMU off") justifies cleaning and invalidating the dcache after disabling the MMU by saying it's nice not to rely on the current page tables and that it should still work (per the spec), as long as there's an identity map in the current tables. Doing the invalidation after also somewhat helped with reenabling the MMU without seeing stale data, but the real problem with reenabling was because the cache needs to be disabled with the MMU, but it wasn't. Since we have to trust/validate that the current page tables have an identity map anyway, then there's no harm in doing the clean and invalidate first (it feels a little better to do so, anyway, considering the cache maintenance instructions take virtual addresses). Then, also disable the cache with the MMU to avoid problems when reenabling. We invalidate the Icache and disable that too for good measure. And, a final TLB invalidation ensures we're crystal clean when we return from asm_mmu_disable(). Cc: Alexandru Elisei Signed-off-by: Andrew Jones Signed-off-by: Nikos Nikoleris --- arm/cstart.S | 28 +++++++++++++++++++++------- arm/cstart64.S | 21 ++++++++++++++++----- 2 files changed, 37 insertions(+), 12 deletions(-) diff --git a/arm/cstart.S b/arm/cstart.S index 7036e67..dc324c5 100644 --- a/arm/cstart.S +++ b/arm/cstart.S @@ -179,6 +179,7 @@ halt: .globl asm_mmu_enable asm_mmu_enable: /* TLBIALL */ + mov r2, #0 mcr p15, 0, r2, c8, c7, 0 dsb nsh @@ -211,12 +212,7 @@ asm_mmu_enable: .globl asm_mmu_disable asm_mmu_disable: - /* SCTLR */ - mrc p15, 0, r0, c1, c0, 0 - bic r0, #CR_M - mcr p15, 0, r0, c1, c0, 0 - isb - + /* Clean + invalidate the entire memory */ ldr r0, =__phys_offset ldr r0, [r0] ldr r1, =__phys_end @@ -224,7 +220,25 @@ asm_mmu_disable: sub r1, r1, r0 dcache_by_line_op dccimvac, sy, r0, r1, r2, r3 - mov pc, lr + /* Invalidate Icache */ + mov r0, #0 + mcr p15, 0, r0, c7, c5, 0 + isb + + /* Disable cache, Icache and MMU */ + mrc p15, 0, r0, c1, c0, 0 + bic r0, #CR_C + bic r0, #CR_I + bic r0, #CR_M + mcr p15, 0, r0, c1, c0, 0 + isb + + /* Invalidate TLB */ + mov r0, #0 + mcr p15, 0, r0, c8, c7, 0 + dsb nsh + + mov pc, lr /* * Vectors diff --git a/arm/cstart64.S b/arm/cstart64.S index e4ab7d0..390feb9 100644 --- a/arm/cstart64.S +++ b/arm/cstart64.S @@ -246,11 +246,6 @@ asm_mmu_enable: .globl asm_mmu_disable asm_mmu_disable: - mrs x0, sctlr_el1 - bic x0, x0, SCTLR_EL1_M - msr sctlr_el1, x0 - isb - /* Clean + invalidate the entire memory */ adrp x0, __phys_offset ldr x0, [x0, :lo12:__phys_offset] @@ -259,6 +254,22 @@ asm_mmu_disable: sub x1, x1, x0 dcache_by_line_op civac, sy, x0, x1, x2, x3 + /* Invalidate Icache */ + ic iallu + isb + + /* Disable cache, Icache and MMU */ + mrs x0, sctlr_el1 + bic x0, x0, SCTLR_EL1_C + bic x0, x0, SCTLR_EL1_I + bic x0, x0, SCTLR_EL1_M + msr sctlr_el1, x0 + isb + + /* Invalidate TLB */ + tlbi vmalle1 + dsb nsh + ret /*