From patchwork Wed Dec 19 18:03:23 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Marc Zyngier X-Patchwork-Id: 10737895 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 5FD2013BF for ; Wed, 19 Dec 2018 18:05:29 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 50DFC2B76B for ; Wed, 19 Dec 2018 18:05:29 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 4514C2B7A7; Wed, 19 Dec 2018 18:05:29 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 6D9312B76B for ; Wed, 19 Dec 2018 18:05:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=aJTyDYaA1GEXzp0GLtli2/v+Mfz3J+ejnd11mg7ZG+Y=; b=XP/eaTXYr6NQ7D iJnxfdMGP6lp7obDRrYyj8Hbi9XqmaOcbhTenLNeITKxOW/fwPjGDbX/tQgoEelzyqwWDQjK7cY5w 7RUkDvwXw5UseejwlkDaZkXmxWzPNfAGjK2UMF6QEl0vfhT9DOJoFawXlAh6+zKWnzRHJ68SrvXee KvlYlyU0zzKZu6CTrcg46CehZBhL2Yh4DI3N+ZNNFS/Au/Z4XWg4dyUDQxtb15R8ASRce6zw1HcNy NZF6YKqQHESVRionLUzD/rshpG961PNv+ZT8pwIZnPCRNvgpqnYJ22zYzeygYV5HqX54AOGsYZI2P v2Fcjs7eoW6tG3XD5XGQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gZgDj-0007wf-I5; Wed, 19 Dec 2018 18:05:23 +0000 Received: from foss.arm.com ([217.140.101.70]) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gZgCi-0005oE-TO for linux-arm-kernel@lists.infradead.org; Wed, 19 Dec 2018 18:04:24 +0000 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 3098B15BE; Wed, 19 Dec 2018 10:04:15 -0800 (PST) Received: from filthy-habits.cambridge.arm.com (filthy-habits.cambridge.arm.com [10.1.196.62]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 81D7B3F675; Wed, 19 Dec 2018 10:04:12 -0800 (PST) From: Marc Zyngier To: Paolo Bonzini , =?utf-8?b?UmFkaW0gS3LEjW3DocWZ?= Subject: [PATCH 02/28] arm64: KVM: Consistently advance singlestep when emulating instructions Date: Wed, 19 Dec 2018 18:03:23 +0000 Message-Id: <20181219180349.242681-3-marc.zyngier@arm.com> X-Mailer: git-send-email 2.19.2 In-Reply-To: <20181219180349.242681-1-marc.zyngier@arm.com> References: <20181219180349.242681-1-marc.zyngier@arm.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20181219_100421_064353_D4451B1C X-CRM114-Status: GOOD ( 23.85 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Punit Agrawal , kvm@vger.kernel.org, Julien Thierry , "Gustavo A . R . Silva" , Will Deacon , Christoffer Dall , linux-arm-kernel@lists.infradead.org, punitagrawal@gmail.com, =?utf-8?q?Ale?= =?utf-8?q?x_Benn=C3=A9e?= , kvmarm@lists.cs.columbia.edu, Suzuki Poulose , Lukas Braun Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP From: Mark Rutland When we emulate a guest instruction, we don't advance the hardware singlestep state machine, and thus the guest will receive a software step exception after a next instruction which is not emulated by the host. We bodge around this in an ad-hoc fashion. Sometimes we explicitly check whether userspace requested a single step, and fake a debug exception from within the kernel. Other times, we advance the HW singlestep state rely on the HW to generate the exception for us. Thus, the observed step behaviour differs for host and guest. Let's make this simpler and consistent by always advancing the HW singlestep state machine when we skip an instruction. Thus we can rely on the hardware to generate the singlestep exception for us, and never need to explicitly check for an active-pending step, nor do we need to fake a debug exception from the guest. Cc: Peter Maydell Reviewed-by: Alex Bennée Reviewed-by: Christoffer Dall Signed-off-by: Mark Rutland Signed-off-by: Marc Zyngier --- arch/arm/include/asm/kvm_host.h | 5 --- arch/arm64/include/asm/kvm_emulate.h | 35 ++++++++++++++----- arch/arm64/include/asm/kvm_host.h | 1 - arch/arm64/kvm/debug.c | 21 ------------ arch/arm64/kvm/handle_exit.c | 14 +------- arch/arm64/kvm/hyp/switch.c | 43 +++--------------------- arch/arm64/kvm/hyp/vgic-v2-cpuif-proxy.c | 12 +++++-- virt/kvm/arm/arm.c | 2 -- virt/kvm/arm/hyp/vgic-v3-sr.c | 6 +++- 9 files changed, 46 insertions(+), 93 deletions(-) diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h index 5ca5d9af0c26..c5634c6ffcea 100644 --- a/arch/arm/include/asm/kvm_host.h +++ b/arch/arm/include/asm/kvm_host.h @@ -296,11 +296,6 @@ static inline void kvm_arm_init_debug(void) {} static inline void kvm_arm_setup_debug(struct kvm_vcpu *vcpu) {} static inline void kvm_arm_clear_debug(struct kvm_vcpu *vcpu) {} static inline void kvm_arm_reset_debug_ptr(struct kvm_vcpu *vcpu) {} -static inline bool kvm_arm_handle_step_debug(struct kvm_vcpu *vcpu, - struct kvm_run *run) -{ - return false; -} int kvm_arm_vcpu_arch_set_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr); diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h index 21247870def7..506386a3edde 100644 --- a/arch/arm64/include/asm/kvm_emulate.h +++ b/arch/arm64/include/asm/kvm_emulate.h @@ -24,6 +24,7 @@ #include +#include #include #include #include @@ -147,14 +148,6 @@ static inline bool kvm_condition_valid(const struct kvm_vcpu *vcpu) return true; } -static inline void kvm_skip_instr(struct kvm_vcpu *vcpu, bool is_wide_instr) -{ - if (vcpu_mode_is_32bit(vcpu)) - kvm_skip_instr32(vcpu, is_wide_instr); - else - *vcpu_pc(vcpu) += 4; -} - static inline void vcpu_set_thumb(struct kvm_vcpu *vcpu) { *vcpu_cpsr(vcpu) |= PSR_AA32_T_BIT; @@ -424,4 +417,30 @@ static inline unsigned long vcpu_data_host_to_guest(struct kvm_vcpu *vcpu, return data; /* Leave LE untouched */ } +static inline void kvm_skip_instr(struct kvm_vcpu *vcpu, bool is_wide_instr) +{ + if (vcpu_mode_is_32bit(vcpu)) + kvm_skip_instr32(vcpu, is_wide_instr); + else + *vcpu_pc(vcpu) += 4; + + /* advance the singlestep state machine */ + *vcpu_cpsr(vcpu) &= ~DBG_SPSR_SS; +} + +/* + * Skip an instruction which has been emulated at hyp while most guest sysregs + * are live. + */ +static inline void __hyp_text __kvm_skip_instr(struct kvm_vcpu *vcpu) +{ + *vcpu_pc(vcpu) = read_sysreg_el2(elr); + vcpu->arch.ctxt.gp_regs.regs.pstate = read_sysreg_el2(spsr); + + kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu)); + + write_sysreg_el2(vcpu->arch.ctxt.gp_regs.regs.pstate, spsr); + write_sysreg_el2(*vcpu_pc(vcpu), elr); +} + #endif /* __ARM64_KVM_EMULATE_H__ */ diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index 52fbc823ff8c..7a5035f9c5c3 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -445,7 +445,6 @@ void kvm_arm_init_debug(void); void kvm_arm_setup_debug(struct kvm_vcpu *vcpu); void kvm_arm_clear_debug(struct kvm_vcpu *vcpu); void kvm_arm_reset_debug_ptr(struct kvm_vcpu *vcpu); -bool kvm_arm_handle_step_debug(struct kvm_vcpu *vcpu, struct kvm_run *run); int kvm_arm_vcpu_arch_set_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr); int kvm_arm_vcpu_arch_get_attr(struct kvm_vcpu *vcpu, diff --git a/arch/arm64/kvm/debug.c b/arch/arm64/kvm/debug.c index 00d422336a45..f39801e4136c 100644 --- a/arch/arm64/kvm/debug.c +++ b/arch/arm64/kvm/debug.c @@ -236,24 +236,3 @@ void kvm_arm_clear_debug(struct kvm_vcpu *vcpu) } } } - - -/* - * After successfully emulating an instruction, we might want to - * return to user space with a KVM_EXIT_DEBUG. We can only do this - * once the emulation is complete, though, so for userspace emulations - * we have to wait until we have re-entered KVM before calling this - * helper. - * - * Return true (and set exit_reason) to return to userspace or false - * if no further action is required. - */ -bool kvm_arm_handle_step_debug(struct kvm_vcpu *vcpu, struct kvm_run *run) -{ - if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) { - run->exit_reason = KVM_EXIT_DEBUG; - run->debug.arch.hsr = ESR_ELx_EC_SOFTSTP_LOW << ESR_ELx_EC_SHIFT; - return true; - } - return false; -} diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c index 35a81bebd02b..b0643f9c4873 100644 --- a/arch/arm64/kvm/handle_exit.c +++ b/arch/arm64/kvm/handle_exit.c @@ -229,13 +229,6 @@ static int handle_trap_exceptions(struct kvm_vcpu *vcpu, struct kvm_run *run) handled = exit_handler(vcpu, run); } - /* - * kvm_arm_handle_step_debug() sets the exit_reason on the kvm_run - * structure if we need to return to userspace. - */ - if (handled > 0 && kvm_arm_handle_step_debug(vcpu, run)) - handled = 0; - return handled; } @@ -269,12 +262,7 @@ int handle_exit(struct kvm_vcpu *vcpu, struct kvm_run *run, case ARM_EXCEPTION_IRQ: return 1; case ARM_EXCEPTION_EL1_SERROR: - /* We may still need to return for single-step */ - if (!(*vcpu_cpsr(vcpu) & DBG_SPSR_SS) - && kvm_arm_handle_step_debug(vcpu, run)) - return 0; - else - return 1; + return 1; case ARM_EXCEPTION_TRAP: return handle_trap_exceptions(vcpu, run); case ARM_EXCEPTION_HYP_GONE: diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c index 7cc175c88a37..4282f05771c1 100644 --- a/arch/arm64/kvm/hyp/switch.c +++ b/arch/arm64/kvm/hyp/switch.c @@ -305,33 +305,6 @@ static bool __hyp_text __populate_fault_info(struct kvm_vcpu *vcpu) return true; } -/* Skip an instruction which has been emulated. Returns true if - * execution can continue or false if we need to exit hyp mode because - * single-step was in effect. - */ -static bool __hyp_text __skip_instr(struct kvm_vcpu *vcpu) -{ - *vcpu_pc(vcpu) = read_sysreg_el2(elr); - - if (vcpu_mode_is_32bit(vcpu)) { - vcpu->arch.ctxt.gp_regs.regs.pstate = read_sysreg_el2(spsr); - kvm_skip_instr32(vcpu, kvm_vcpu_trap_il_is32bit(vcpu)); - write_sysreg_el2(vcpu->arch.ctxt.gp_regs.regs.pstate, spsr); - } else { - *vcpu_pc(vcpu) += 4; - } - - write_sysreg_el2(*vcpu_pc(vcpu), elr); - - if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) { - vcpu->arch.fault.esr_el2 = - (ESR_ELx_EC_SOFTSTP_LOW << ESR_ELx_EC_SHIFT) | 0x22; - return false; - } else { - return true; - } -} - static bool __hyp_text __hyp_switch_fpsimd(struct kvm_vcpu *vcpu) { struct user_fpsimd_state *host_fpsimd = vcpu->arch.host_fpsimd_state; @@ -420,20 +393,12 @@ static bool __hyp_text fixup_guest_exit(struct kvm_vcpu *vcpu, u64 *exit_code) if (valid) { int ret = __vgic_v2_perform_cpuif_access(vcpu); - if (ret == 1 && __skip_instr(vcpu)) + if (ret == 1) return true; - if (ret == -1) { - /* Promote an illegal access to an - * SError. If we would be returning - * due to single-step clear the SS - * bit so handle_exit knows what to - * do after dealing with the error. - */ - if (!__skip_instr(vcpu)) - *vcpu_cpsr(vcpu) &= ~DBG_SPSR_SS; + /* Promote an illegal access to an SError.*/ + if (ret == -1) *exit_code = ARM_EXCEPTION_EL1_SERROR; - } goto exit; } @@ -444,7 +409,7 @@ static bool __hyp_text fixup_guest_exit(struct kvm_vcpu *vcpu, u64 *exit_code) kvm_vcpu_trap_get_class(vcpu) == ESR_ELx_EC_CP15_32)) { int ret = __vgic_v3_perform_cpuif_access(vcpu); - if (ret == 1 && __skip_instr(vcpu)) + if (ret == 1) return true; } diff --git a/arch/arm64/kvm/hyp/vgic-v2-cpuif-proxy.c b/arch/arm64/kvm/hyp/vgic-v2-cpuif-proxy.c index 215c7c0eb3b0..9cbdd034a563 100644 --- a/arch/arm64/kvm/hyp/vgic-v2-cpuif-proxy.c +++ b/arch/arm64/kvm/hyp/vgic-v2-cpuif-proxy.c @@ -41,7 +41,7 @@ static bool __hyp_text __is_be(struct kvm_vcpu *vcpu) * Returns: * 1: GICV access successfully performed * 0: Not a GICV access - * -1: Illegal GICV access + * -1: Illegal GICV access successfully performed */ int __hyp_text __vgic_v2_perform_cpuif_access(struct kvm_vcpu *vcpu) { @@ -61,12 +61,16 @@ int __hyp_text __vgic_v2_perform_cpuif_access(struct kvm_vcpu *vcpu) return 0; /* Reject anything but a 32bit access */ - if (kvm_vcpu_dabt_get_as(vcpu) != sizeof(u32)) + if (kvm_vcpu_dabt_get_as(vcpu) != sizeof(u32)) { + __kvm_skip_instr(vcpu); return -1; + } /* Not aligned? Don't bother */ - if (fault_ipa & 3) + if (fault_ipa & 3) { + __kvm_skip_instr(vcpu); return -1; + } rd = kvm_vcpu_dabt_get_rd(vcpu); addr = hyp_symbol_addr(kvm_vgic_global_state)->vcpu_hyp_va; @@ -88,5 +92,7 @@ int __hyp_text __vgic_v2_perform_cpuif_access(struct kvm_vcpu *vcpu) vcpu_set_reg(vcpu, rd, data); } + __kvm_skip_instr(vcpu); + return 1; } diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c index 23774970c9df..4adcee5fc126 100644 --- a/virt/kvm/arm/arm.c +++ b/virt/kvm/arm/arm.c @@ -674,8 +674,6 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run) ret = kvm_handle_mmio_return(vcpu, vcpu->run); if (ret) return ret; - if (kvm_arm_handle_step_debug(vcpu, vcpu->run)) - return 0; } if (run->immediate_exit) diff --git a/virt/kvm/arm/hyp/vgic-v3-sr.c b/virt/kvm/arm/hyp/vgic-v3-sr.c index 616e5a433ab0..9652c453480f 100644 --- a/virt/kvm/arm/hyp/vgic-v3-sr.c +++ b/virt/kvm/arm/hyp/vgic-v3-sr.c @@ -1012,8 +1012,10 @@ int __hyp_text __vgic_v3_perform_cpuif_access(struct kvm_vcpu *vcpu) esr = kvm_vcpu_get_hsr(vcpu); if (vcpu_mode_is_32bit(vcpu)) { - if (!kvm_condition_valid(vcpu)) + if (!kvm_condition_valid(vcpu)) { + __kvm_skip_instr(vcpu); return 1; + } sysreg = esr_cp15_to_sysreg(esr); } else { @@ -1123,6 +1125,8 @@ int __hyp_text __vgic_v3_perform_cpuif_access(struct kvm_vcpu *vcpu) rt = kvm_vcpu_sys_get_rt(vcpu); fn(vcpu, vmcr, rt); + __kvm_skip_instr(vcpu); + return 1; }