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[209.132.180.67]) by mx.google.com with ESMTP id y10si2869429pdn.1.2015.05.15.07.30.51; Fri, 15 May 2015 07:31:21 -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; Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934599AbbEOO3O (ORCPT + 28 others); Fri, 15 May 2015 10:29:14 -0400 Received: from static.88-198-71-155.clients.your-server.de ([88.198.71.155]:36188 "EHLO socrates.bennee.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933985AbbEOO1R (ORCPT ); Fri, 15 May 2015 10:27:17 -0400 Received: from localhost ([127.0.0.1] helo=zen.linaroharston) by socrates.bennee.com with esmtp (Exim 4.80) (envelope-from ) id 1YtHqP-0000D4-Hz; Fri, 15 May 2015 17:48:13 +0200 From: =?UTF-8?q?Alex=20Benn=C3=A9e?= To: kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, christoffer.dall@linaro.org, marc.zyngier@arm.com, peter.maydell@linaro.org, agraf@suse.de, drjones@redhat.com, pbonzini@redhat.com, zhichao.huang@linaro.org Cc: jan.kiszka@siemens.com, dahi@linux.vnet.ibm.com, r65777@freescale.com, bp@suse.de, =?UTF-8?q?Alex=20Benn=C3=A9e?= , Gleb Natapov , Russell King , Catalin Marinas , Will Deacon , linux-kernel@vger.kernel.org (open list) Subject: [PATCH v4 07/12] KVM: arm64: guest debug, add support for single-step Date: Fri, 15 May 2015 15:27:10 +0100 Message-Id: <1431700035-23479-8-git-send-email-alex.bennee@linaro.org> X-Mailer: git-send-email 2.3.5 In-Reply-To: <1431700035-23479-1-git-send-email-alex.bennee@linaro.org> References: <1431700035-23479-1-git-send-email-alex.bennee@linaro.org> MIME-Version: 1.0 X-SA-Exim-Connect-IP: 127.0.0.1 X-SA-Exim-Mail-From: alex.bennee@linaro.org X-SA-Exim-Scanned: No (on socrates.bennee.com); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: list List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-Removed-Original-Auth: Dkim didn't pass. X-Original-Sender: alex.bennee@linaro.org X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of patch+caf_=patchwork-forward=linaro.org@linaro.org designates 209.85.215.53 as permitted sender) smtp.mail=patch+caf_=patchwork-forward=linaro.org@linaro.org Mailing-list: list patchwork-forward@linaro.org; contact patchwork-forward+owners@linaro.org X-Google-Group-Id: 836684582541 List-Post: , List-Help: , List-Archive: List-Unsubscribe: , This adds support for single-stepping the guest. To do this we need to manipulate the guests PSTATE.SS and MDSCR_EL1.SS bits which we do in the kvm_arm_setup/clear_debug() so we don't affect the apparent state of the guest. Additionally while the host is debugging the guest we suppress the ability of the guest to single-step itself. Signed-off-by: Alex Bennée --- v2 - Move pstate/mdscr manipulation into C - don't export guest_debug to assembly - add accessor for saved_debug regs - tweak save/restore of mdscr_el1 v3 - don't save PC in debug information struct - rename debug_saved_regs->guest_debug_state - save whole value, only use bits in restore - add save/restore_guest-debug_regs helper functions - simplify commit message for clarity - rm vcpu_debug_saved_reg access fn v4 - added more comments based on suggestions - guest_debug_state->guest_debug_preserved - no point masking restore, we will trap out diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c index 064c105..9b3ed6d 100644 --- a/arch/arm/kvm/arm.c +++ b/arch/arm/kvm/arm.c @@ -302,7 +302,9 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu) kvm_arm_set_running_vcpu(NULL); } -#define KVM_GUESTDBG_VALID_MASK (KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_SW_BP) +#define KVM_GUESTDBG_VALID_MASK (KVM_GUESTDBG_ENABLE | \ + KVM_GUESTDBG_USE_SW_BP | \ + KVM_GUESTDBG_SINGLESTEP) /** * kvm_arch_vcpu_ioctl_set_guest_debug - set up guest debugging diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index 7cb99b5..3ab31d7 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -123,6 +123,18 @@ struct kvm_vcpu_arch { * here. */ + /* + * Guest registers we preserve during guest debugging. + * + * These shadow registers are updated by the kvm_handle_sys_reg + * trap handler if the guest accesses or updates them while we + * are using guest debug. + */ + struct { + u32 pstate; /* preserve SPSR_DEBUG_MASK bits */ + u32 mdscr_el1; + } guest_debug_preserved; + /* Don't run the guest */ bool pause; diff --git a/arch/arm64/kvm/debug.c b/arch/arm64/kvm/debug.c index 8d1bfa4..f630f4d 100644 --- a/arch/arm64/kvm/debug.c +++ b/arch/arm64/kvm/debug.c @@ -19,11 +19,46 @@ #include +#include +#include #include +#include + +/* These are the bits of MDSCR_EL1 we may manipulate */ +#define MDSCR_EL1_DEBUG_MASK (DBG_MDSCR_SS | \ + DBG_MDSCR_KDE | \ + DBG_MDSCR_MDE) + +#define SPSR_DEBUG_MASK DBG_SPSR_SS static DEFINE_PER_CPU(u32, mdcr_el2); /** + * save/restore_guest_debug_regs + * + * For some debug operations we need to tweak some guest registers. As + * a result we need to save the state of those registers before we + * make those modifications. This does get confused if the guest + * attempts to control single step while being debugged. It will start + * working again once it is no longer being debugged by the host. + * + * Guest access to MDSCR_EL1 is trapped by the hypervisor and handled + * after we have restored the preserved value to the main context. + */ +static void save_guest_debug_regs(struct kvm_vcpu *vcpu) +{ + vcpu->arch.guest_debug_preserved.pstate = *vcpu_cpsr(vcpu); + vcpu->arch.guest_debug_preserved.mdscr_el1 = vcpu_sys_reg(vcpu, MDSCR_EL1); +} + +static void restore_guest_debug_regs(struct kvm_vcpu *vcpu) +{ + *vcpu_cpsr(vcpu) |= + (vcpu->arch.guest_debug_preserved.pstate & SPSR_DEBUG_MASK); + vcpu_sys_reg(vcpu, MDSCR_EL1) = vcpu->arch.guest_debug_preserved.mdscr_el1; +} + +/** * kvm_arm_init_debug - grab what we need for debug * * Currently the sole task of this function is to retrieve the initial @@ -38,7 +73,6 @@ void kvm_arm_init_debug(void) __this_cpu_write(mdcr_el2, kvm_call_hyp(__kvm_get_mdcr_el2)); } - /** * kvm_arm_setup_debug - set up debug related stuff * @@ -73,12 +107,33 @@ void kvm_arm_setup_debug(struct kvm_vcpu *vcpu) if (trap_debug) vcpu->arch.mdcr_el2 |= MDCR_EL2_TDA; - /* Trap breakpoints? */ - if (vcpu->guest_debug & KVM_GUESTDBG_USE_SW_BP) + /* Is Guest debugging in effect? */ + if (vcpu->guest_debug) { vcpu->arch.mdcr_el2 |= MDCR_EL2_TDE; + + /* Save guest debug state */ + save_guest_debug_regs(vcpu); + + /* + * Single Step (ARM ARM D2.12.3 The software step state + * machine) + * + * If we are doing Single Step we need to manipulate + * MDSCR_EL1.SS and PSTATE.SS. If not we need to + * suppress the guests ability to trigger single step itself. + */ + if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) { + *vcpu_cpsr(vcpu) |= DBG_SPSR_SS; + vcpu_sys_reg(vcpu, MDSCR_EL1) |= DBG_MDSCR_SS; + } else { + *vcpu_cpsr(vcpu) &= ~DBG_SPSR_SS; + vcpu_sys_reg(vcpu, MDSCR_EL1) &= ~DBG_MDSCR_SS; + } + } } void kvm_arm_clear_debug(struct kvm_vcpu *vcpu) { - /* Nothing to do yet */ + if (vcpu->guest_debug) + restore_guest_debug_regs(vcpu); } diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c index 27f38a9..e9de13e 100644 --- a/arch/arm64/kvm/handle_exit.c +++ b/arch/arm64/kvm/handle_exit.c @@ -103,6 +103,7 @@ static int kvm_handle_guest_debug(struct kvm_vcpu *vcpu, struct kvm_run *run) run->debug.arch.hsr = hsr; switch (hsr >> ESR_ELx_EC_SHIFT) { + case ESR_ELx_EC_SOFTSTP_LOW: case ESR_ELx_EC_BKPT32: case ESR_ELx_EC_BRK64: break; @@ -130,6 +131,7 @@ static exit_handle_fn arm_exit_handlers[] = { [ESR_ELx_EC_SYS64] = kvm_handle_sys_reg, [ESR_ELx_EC_IABT_LOW] = kvm_handle_guest_abort, [ESR_ELx_EC_DABT_LOW] = kvm_handle_guest_abort, + [ESR_ELx_EC_SOFTSTP_LOW]= kvm_handle_guest_debug, [ESR_ELx_EC_BKPT32] = kvm_handle_guest_debug, [ESR_ELx_EC_BRK64] = kvm_handle_guest_debug, };