From patchwork Fri Jan 31 16:37:28 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexandru Elisei X-Patchwork-Id: 11360269 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id D531F924 for ; Fri, 31 Jan 2020 16:38:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B320C215A4 for ; Fri, 31 Jan 2020 16:38:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726157AbgAaQiV (ORCPT ); Fri, 31 Jan 2020 11:38:21 -0500 Received: from foss.arm.com ([217.140.110.172]:37384 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726916AbgAaQiV (ORCPT ); Fri, 31 Jan 2020 11:38:21 -0500 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 74CD3FEC; Fri, 31 Jan 2020 08:38:20 -0800 (PST) Received: from e123195-lin.cambridge.arm.com (e123195-lin.cambridge.arm.com [10.1.196.63]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 756403F68E; Fri, 31 Jan 2020 08:38:19 -0800 (PST) From: Alexandru Elisei To: kvm@vger.kernel.org Cc: pbonzini@redhat.com, drjones@redhat.com, maz@kernel.org, andre.przywara@arm.com, vladimir.murzin@arm.com, mark.rutland@arm.com Subject: [kvm-unit-tests PATCH v4 10/10] arm/arm64: Perform dcache clean + invalidate after turning MMU off Date: Fri, 31 Jan 2020 16:37:28 +0000 Message-Id: <20200131163728.5228-11-alexandru.elisei@arm.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200131163728.5228-1-alexandru.elisei@arm.com> References: <20200131163728.5228-1-alexandru.elisei@arm.com> MIME-Version: 1.0 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org When the MMU is off, data accesses are to Device nGnRnE memory on arm64 [1] or to Strongly-Ordered memory on arm [2]. This means that the accesses are non-cacheable. Perform a dcache clean to PoC so we can read the newer values from the cache after we turn the MMU off, instead of the stale values from memory. Perform an invalidation so we can access the data written to memory after we turn the MMU back on. This prevents reading back the stale values we cleaned from the cache when we turned the MMU off. Data caches are PIPT and the VAs are translated using the current translation tables, or an identity mapping (what Arm calls a "flat mapping") when the MMU is off [1, 2]. Do the clean + invalidate when the MMU is off so we don't depend on the current translation tables and we can make sure that the operation applies to the entire physical memory. The patch was tested by hacking arm/selftest.c: +#include +#include int main(int argc, char **argv) { + int *x = alloc_page(); + report_prefix_push("selftest"); + *x = 0x42; + mmu_disable(); + report(*x == 0x42, "read back value written with MMU on"); + *x = 0x50; + mmu_enable(current_thread_info()->pgtable); + report(*x == 0x50, "read back value written with MMU off"); + if (argc < 2) report_abort("no test specified"); Without the fix, the first report fails, and the test usually hangs before the second report. This is because mmu_enable pushes the LR register on the stack when the MMU is off, which means that the value will be written to memory. However, after asm_mmu_enable, the MMU is enabled, and we read it back from the dcache, thus getting garbage. With the fix, the two reports pass. [1] ARM DDI 0487E.a, section D5.2.9 [2] ARM DDI 0406C.d, section B3.2.1 Signed-off-by: Alexandru Elisei --- lib/arm/asm/processor.h | 13 +++++++++++++ lib/arm64/asm/processor.h | 12 ++++++++++++ lib/arm/setup.c | 8 ++++++++ arm/cstart.S | 22 ++++++++++++++++++++++ arm/cstart64.S | 23 +++++++++++++++++++++++ 5 files changed, 78 insertions(+) diff --git a/lib/arm/asm/processor.h b/lib/arm/asm/processor.h index a8c4628da818..1e1132dafd2b 100644 --- a/lib/arm/asm/processor.h +++ b/lib/arm/asm/processor.h @@ -9,6 +9,11 @@ #include #include +#define CTR_DMINLINE_SHIFT 16 +#define CTR_DMINLINE_MASK (0xf << 16) +#define CTR_DMINLINE(x) \ + (((x) & CTR_DMINLINE_MASK) >> CTR_DMINLINE_SHIFT) + enum vector { EXCPTN_RST, EXCPTN_UND, @@ -64,6 +69,7 @@ extern bool is_user(void); #define CNTVCT __ACCESS_CP15_64(1, c14) #define CNTFRQ __ACCESS_CP15(c14, 0, c0, 0) +#define CTR __ACCESS_CP15(c0, 0, c0, 1) static inline u64 get_cntvct(void) { @@ -76,4 +82,11 @@ static inline u32 get_cntfrq(void) return read_sysreg(CNTFRQ); } +static inline u32 get_ctr(void) +{ + return read_sysreg(CTR); +} + +extern u32 dcache_line_size; + #endif /* _ASMARM_PROCESSOR_H_ */ diff --git a/lib/arm64/asm/processor.h b/lib/arm64/asm/processor.h index 1d9223f728a5..02665b84cc7e 100644 --- a/lib/arm64/asm/processor.h +++ b/lib/arm64/asm/processor.h @@ -16,6 +16,11 @@ #define SCTLR_EL1_A (1 << 1) #define SCTLR_EL1_M (1 << 0) +#define CTR_DMINLINE_SHIFT 16 +#define CTR_DMINLINE_MASK (0xf << 16) +#define CTR_DMINLINE(x) \ + (((x) & CTR_DMINLINE_MASK) >> CTR_DMINLINE_SHIFT) + #ifndef __ASSEMBLY__ #include #include @@ -105,5 +110,12 @@ static inline u32 get_cntfrq(void) return read_sysreg(cntfrq_el0); } +static inline u64 get_ctr(void) +{ + return read_sysreg(ctr_el0); +} + +extern u32 dcache_line_size; + #endif /* !__ASSEMBLY__ */ #endif /* _ASMARM64_PROCESSOR_H_ */ diff --git a/lib/arm/setup.c b/lib/arm/setup.c index 385e135f4865..418b4e58a5f8 100644 --- a/lib/arm/setup.c +++ b/lib/arm/setup.c @@ -20,6 +20,7 @@ #include #include #include +#include #include #include "io.h" @@ -38,6 +39,8 @@ static struct mem_region __initial_mem_regions[NR_INITIAL_MEM_REGIONS + 1]; struct mem_region *mem_regions = __initial_mem_regions; phys_addr_t __phys_offset, __phys_end; +u32 dcache_line_size; + int mpidr_to_cpu(uint64_t mpidr) { int i; @@ -66,6 +69,11 @@ static void cpu_init(void) ret = dt_for_each_cpu_node(cpu_set, NULL); assert(ret == 0); set_cpu_online(0, true); + /* + * DminLine is log2 of the number of words in the smallest cache line; a + * word is 4 bytes. + */ + dcache_line_size = 1 << (CTR_DMINLINE(get_ctr()) + 2); } unsigned int mem_region_get_flags(phys_addr_t paddr) diff --git a/arm/cstart.S b/arm/cstart.S index e54e380e0d53..ef936ae2f874 100644 --- a/arm/cstart.S +++ b/arm/cstart.S @@ -197,6 +197,20 @@ asm_mmu_enable: mov pc, lr +.macro dcache_clean_inval domain, start, end, tmp1, tmp2 + ldr \tmp1, =dcache_line_size + ldr \tmp1, [\tmp1] + sub \tmp2, \tmp1, #1 + bic \start, \start, \tmp2 +9998: + /* DCCIMVAC */ + mcr p15, 0, \start, c7, c14, 1 + add \start, \start, \tmp1 + cmp \start, \end + blo 9998b + dsb \domain +.endm + .globl asm_mmu_disable asm_mmu_disable: /* SCTLR */ @@ -204,6 +218,14 @@ asm_mmu_disable: bic r0, #CR_M mcr p15, 0, r0, c1, c0, 0 isb + + ldr r0, =__phys_offset + ldr r0, [r0] + ldr r1, =__phys_end + ldr r1, [r1] + dcache_clean_inval sy, r0, r1, r2, r3 + isb + mov pc, lr /* diff --git a/arm/cstart64.S b/arm/cstart64.S index e5a561ea2e39..ffdd49f73ddd 100644 --- a/arm/cstart64.S +++ b/arm/cstart64.S @@ -193,12 +193,35 @@ asm_mmu_enable: ret +/* Taken with small changes from arch/arm64/incluse/asm/assembler.h */ +.macro dcache_by_line_op op, domain, start, end, tmp1, tmp2 + adrp \tmp1, dcache_line_size + ldr \tmp1, [\tmp1, :lo12:dcache_line_size] + sub \tmp2, \tmp1, #1 + bic \start, \start, \tmp2 +9998: + dc \op , \start + add \start, \start, \tmp1 + cmp \start, \end + b.lo 9998b + dsb \domain +.endm + .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] + adrp x1, __phys_end + ldr x1, [x1, :lo12:__phys_end] + dcache_by_line_op civac, sy, x0, x1, x2, x3 + isb + ret /*