From patchwork Tue Jun 12 11:36:40 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Julien Grall X-Patchwork-Id: 138328 Delivered-To: patch@linaro.org Received: by 2002:a2e:970d:0:0:0:0:0 with SMTP id r13-v6csp5234999lji; Tue, 12 Jun 2018 04:39:32 -0700 (PDT) X-Google-Smtp-Source: ADUXVKLaUt13CTBmALSFqATXCiiYRl5GLGq9Iou0DuP4Ul7+GN3oCnNV0olN5188fwXxRHrr7NzB X-Received: by 2002:a6b:9403:: with SMTP id w3-v6mr20522iod.108.1528803572474; Tue, 12 Jun 2018 04:39:32 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1528803572; cv=none; d=google.com; s=arc-20160816; b=QDw0wik292L+uivTkTfoLwzCMDmNH7hrHHdwW4F5PD9u8A2Ci/FnwNsdShKW55QsuU +b85H8aQvt6rx8CAAbPE8rFqo+vfoAkjlNud5aNBLgVozIcCRlA1Cm4N0TdlRV8HYsSB utiCMcfVAOvdT0J8Kezmev3tLoDeaaSVOw2i2wbGE5s2FhW3qjnNNiPBI18Lw55KC/6/ oicm4rodAekEq6+IOakRCvkz0Ouvs3s8YeA76ac8ewtb+foA9jCzzvgSyx5/wXmoD+BV v7UMFxa4e44G7dwCFZTI3QbsGU1o91Ah/UE3QABridO253ZE8uKmSwCyTq+F2rB6V6pk 4OOw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=sender:errors-to:content-transfer-encoding:mime-version:cc :list-subscribe:list-help:list-post:list-unsubscribe:list-id :precedence:subject:references:in-reply-to:message-id:date:to:from :arc-authentication-results; bh=MDhEKpm8SiKDGW68e0hUnfI4WuGChq7a0s9p9rJi/t8=; b=hB49vfudifdTjvqYuO4ELM1BJNUkGlUJhZ8POKLi6pt9g7k7nKQhmuAIvKzI8ysRiZ V10tGbak2gVID9GzNWlKDg1PWD1s7bMadu+PEE6U8FkBWajQTDRFfa3KGy/yt2OUl68e tivoNgaFm/XHLnDFSQqM1ZzFBAS6C9Znaxrcg39gpotZQ8tstlSzmVERWhqav9sO8Oh0 DTpiFIaIEXOX327C88XzuNWZtWZFIluVndmRYRcSiJsTaMqFrU6UKTuzhCn+THGVq3ok bZBYEbM/NRogmDVQWrHZ2kF/MNaVCLnDr7rjJOjPhxhAIgglpm+d4XBxnlIWjLWB+GUe WRRw== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of xen-devel-bounces@lists.xenproject.org designates 192.237.175.120 as permitted sender) smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Return-Path: Received: from lists.xenproject.org (lists.xenproject.org. [192.237.175.120]) by mx.google.com with ESMTPS id g14-v6si661387iog.51.2018.06.12.04.39.32 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 12 Jun 2018 04:39:32 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of xen-devel-bounces@lists.xenproject.org designates 192.237.175.120 as permitted sender) client-ip=192.237.175.120; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of xen-devel-bounces@lists.xenproject.org designates 192.237.175.120 as permitted sender) smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1fShbk-0000tb-4g; Tue, 12 Jun 2018 11:37:04 +0000 Received: from all-amaz-eas1.inumbo.com ([34.197.232.57]) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1fShbj-0000rX-0h for xen-devel@lists.xenproject.org; Tue, 12 Jun 2018 11:37:03 +0000 X-Inumbo-ID: ef58640b-6e34-11e8-bc1d-65256ead4e3a Received: from foss.arm.com (unknown [217.140.101.70]) by us1-amaz-eas1.inumbo.com (Halon) with ESMTP id ef58640b-6e34-11e8-bc1d-65256ead4e3a; Tue, 12 Jun 2018 11:37:06 +0000 (UTC) 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 EB73E1435; Tue, 12 Jun 2018 04:37:01 -0700 (PDT) Received: from e108454-lin.cambridge.arm.com (e108454-lin.cambridge.arm.com [10.1.206.53]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 0D6A73F318; Tue, 12 Jun 2018 04:37:00 -0700 (PDT) From: Julien Grall To: xen-devel@lists.xenproject.org Date: Tue, 12 Jun 2018 12:36:40 +0100 Message-Id: <20180612113643.32020-11-julien.grall@arm.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20180612113643.32020-1-julien.grall@arm.com> References: <20180612113643.32020-1-julien.grall@arm.com> Subject: [Xen-devel] [PATCH v3 10/13] xen/arm64: Implement a fast path for handling SMCCC_ARCH_WORKAROUND_2 X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: andre.przywara@arm.com, Julien Grall , sstabellini@kernel.org MIME-Version: 1.0 Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" The function ARM_SMCCC_ARCH_WORKAROUND_2 will be called by the guest for enabling/disabling the ssbd mitigation. So we want the handling to be as fast as possible. The new sequence will forward guest's ARCH_WORKAROUND_2 call to EL3 and also track the state of the workaround per-vCPU. Note that since we need to execute branches, this always executes after the spectre-v2 mitigation. This code is based on KVM counterpart "arm64: KVM: Handle guest's ARCH_WORKAROUND_2 requests" written by Marc Zyngier. This is part of XSA-263. Signed-off-by: Julien Grall Reviewed-by: Stefano Stabellini --- Changes in v3: - Add Stefano's reviewed-by Changes in v2: - Combine the 2 consecutive eor instructions in a single one. --- xen/arch/arm/arm64/asm-offsets.c | 2 ++ xen/arch/arm/arm64/entry.S | 42 +++++++++++++++++++++++++++++++++++++++- xen/arch/arm/cpuerrata.c | 18 +++++++++++++++++ 3 files changed, 61 insertions(+), 1 deletion(-) diff --git a/xen/arch/arm/arm64/asm-offsets.c b/xen/arch/arm/arm64/asm-offsets.c index ce24e44473..f5c696d092 100644 --- a/xen/arch/arm/arm64/asm-offsets.c +++ b/xen/arch/arm/arm64/asm-offsets.c @@ -22,6 +22,7 @@ void __dummy__(void) { OFFSET(UREGS_X0, struct cpu_user_regs, x0); + OFFSET(UREGS_X1, struct cpu_user_regs, x1); OFFSET(UREGS_LR, struct cpu_user_regs, lr); OFFSET(UREGS_SP, struct cpu_user_regs, sp); @@ -45,6 +46,7 @@ void __dummy__(void) BLANK(); DEFINE(CPUINFO_sizeof, sizeof(struct cpu_info)); + OFFSET(CPUINFO_flags, struct cpu_info, flags); OFFSET(VCPU_arch_saved_context, struct vcpu, arch.saved_context); diff --git a/xen/arch/arm/arm64/entry.S b/xen/arch/arm/arm64/entry.S index e2344e565f..97b05f53ea 100644 --- a/xen/arch/arm/arm64/entry.S +++ b/xen/arch/arm/arm64/entry.S @@ -1,4 +1,6 @@ #include +#include +#include #include #include #include @@ -241,7 +243,7 @@ guest_sync: * be encoded as an immediate for cmp. */ eor w0, w0, #ARM_SMCCC_ARCH_WORKAROUND_1_FID - cbnz w0, guest_sync_slowpath + cbnz w0, check_wa2 /* * Clobber both x0 and x1 to prevent leakage. Note that thanks @@ -250,6 +252,44 @@ guest_sync: mov x1, xzr eret +check_wa2: + /* ARM_SMCCC_ARCH_WORKAROUND_2 handling */ + eor w0, w0, #(ARM_SMCCC_ARCH_WORKAROUND_1_FID ^ ARM_SMCCC_ARCH_WORKAROUND_2_FID) + cbnz w0, guest_sync_slowpath +#ifdef CONFIG_ARM_SSBD +alternative_cb arm_enable_wa2_handling + b wa2_end +alternative_cb_end + /* Sanitize the argument */ + mov x0, #-(UREGS_kernel_sizeof - UREGS_X1) /* x0 := offset of guest's x1 on the stack */ + ldr x1, [sp, x0] /* Load guest's x1 */ + cmp w1, wzr + cset x1, ne + + /* + * Update the guest flag. At this stage sp point after the field + * guest_cpu_user_regs in cpu_info. + */ + adr_cpu_info x2 + ldr x0, [x2, #CPUINFO_flags] + bfi x0, x1, #CPUINFO_WORKAROUND_2_FLAG_SHIFT, #1 + str x0, [x2, #CPUINFO_flags] + + /* Check that we actually need to perform the call */ + ldr_this_cpu x0, ssbd_callback_required, x2 + cbz x0, wa2_end + + mov w0, #ARM_SMCCC_ARCH_WORKAROUND_2_FID + smc #0 + +wa2_end: + /* Don't leak data from the SMC call */ + mov x1, xzr + mov x2, xzr + mov x3, xzr +#endif /* !CONFIG_ARM_SSBD */ + mov x0, xzr + eret guest_sync_slowpath: /* * x0/x1 may have been scratch by the fast path above, so avoid diff --git a/xen/arch/arm/cpuerrata.c b/xen/arch/arm/cpuerrata.c index 4292008692..7455f09f26 100644 --- a/xen/arch/arm/cpuerrata.c +++ b/xen/arch/arm/cpuerrata.c @@ -7,6 +7,7 @@ #include #include #include +#include #include /* Override macros from asm/page.h to make them work with mfn_t */ @@ -272,6 +273,23 @@ static int __init parse_spec_ctrl(const char *s) } custom_param("spec-ctrl", parse_spec_ctrl); +/* Arm64 only for now as for Arm32 the workaround is currently handled in C. */ +#ifdef CONFIG_ARM_64 +void __init arm_enable_wa2_handling(const struct alt_instr *alt, + const uint32_t *origptr, + uint32_t *updptr, int nr_inst) +{ + BUG_ON(nr_inst != 1); + + /* + * Only allow mitigation on guest ARCH_WORKAROUND_2 if the SSBD + * state allow it to be flipped. + */ + if ( get_ssbd_state() == ARM_SSBD_RUNTIME ) + *updptr = aarch64_insn_gen_nop(); +} +#endif + /* * Assembly code may use the variable directly, so we need to make sure * it fits in a register.