From patchwork Tue Jul 7 16:30:01 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Alex_Benn=C3=A9e?= X-Patchwork-Id: 6735221 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 4C752C05AC for ; Tue, 7 Jul 2015 16:33:41 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 6A2FA2053F for ; Tue, 7 Jul 2015 16:33:39 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (using TLSv1.2 with cipher AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id EDE90204FC for ; Tue, 7 Jul 2015 16:33:37 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1ZCVmb-0001VL-Kw; Tue, 07 Jul 2015 16:31:45 +0000 Received: from mail-wi0-f178.google.com ([209.85.212.178]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1ZCVlg-0000nx-6Q for linux-arm-kernel@lists.infradead.org; Tue, 07 Jul 2015 16:30:49 +0000 Received: by wiwl6 with SMTP id l6so320055738wiw.0 for ; Tue, 07 Jul 2015 09:30:26 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-type:content-transfer-encoding; bh=/N3e8jpqCRrZNx4JcTvOUjKKE35+Ge31PhPB6KIkMwA=; b=SSdgGI8TGc+xEgSae0as8oImCuWBITaYBFvdUXjblHzMbLuRWeqMqB9FEXoY6QLnsN INj3hldx594bG7E64AXcZz3glVwjKNw1Ut8ardOmEURqptB7OpwLYlBLbwKzy3vY4+xt OcLDnSC3auvniRu5movsUEA+Skbk4yz65r36UQsjFIVPk6Z5jfQoCKBvMS/+mfit1HXm rrflViPURqfqxNQjTfx8KPfQ08K2bjEw00T024euXHvR2nCWGv3s/M80nipAi8VI81yo sxr8j1rqKwijwoXRSh80FUMw1Vu6By9W19vCDWZTpMdXFc8fK+xl4/Jj7bvanr3lfqMf He/Q== X-Gm-Message-State: ALoCoQmbqKGSvASpLIpGF99yCoqhh2jh95+MEI1ihnnGvrKYeH/vp3HqskAqp8GtIqrzPg+IaVI4 X-Received: by 10.194.234.40 with SMTP id ub8mr10273443wjc.21.1436286626568; Tue, 07 Jul 2015 09:30:26 -0700 (PDT) Received: from zen.linaro.local ([81.128.185.34]) by mx.google.com with ESMTPSA id c3sm34158585wja.3.2015.07.07.09.30.24 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 07 Jul 2015 09:30:24 -0700 (PDT) Received: from zen.linaroharston (localhost [127.0.0.1]) by zen.linaro.local (Postfix) with ESMTP id 8D3BF3E065D; Tue, 7 Jul 2015 17:30:23 +0100 (BST) 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 Subject: [PATCH v8 09/11] KVM: arm64: guest debug, HW assisted debug support Date: Tue, 7 Jul 2015 17:30:01 +0100 Message-Id: <1436286603-15192-10-git-send-email-alex.bennee@linaro.org> X-Mailer: git-send-email 2.4.5 In-Reply-To: <1436286603-15192-1-git-send-email-alex.bennee@linaro.org> References: <1436286603-15192-1-git-send-email-alex.bennee@linaro.org> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20150707_093048_571509_D3C3E103 X-CRM114-Status: GOOD ( 31.30 ) X-Spam-Score: -2.6 (--) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Lorenzo Pieralisi , Catalin Marinas , Jonathan Corbet , Gleb Natapov , jan.kiszka@siemens.com, "open list:DOCUMENTATION" , Will Deacon , open list , "open list:ABI/API" , dahi@linux.vnet.ibm.com, Peter Zijlstra , r65777@freescale.com, bp@suse.de, =?UTF-8?q?Alex=20Benn=C3=A9e?= , Ingo Molnar Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-5.0 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP This adds support for userspace to control the HW debug registers for guest debug. In the debug ioctl we copy an IMPDEF registers into a new register set called host_debug_state. We use the recently introduced vcpu parameter debug_ptr to select which register set is copied into the real registers when world switch occurs. I've made some helper functions from hw_breakpoint.c more widely available for re-use. As with single step we need to tweak the guest registers to enable the exceptions so we need to save and restore those bits. Two new capabilities have been added to the KVM_EXTENSION ioctl to allow userspace to query the number of hardware break and watch points available on the host hardware. Signed-off-by: Alex Bennée Reviewed-by: Christoffer Dall --- v2 - switched to C setup - replace host debug registers directly into context - minor tweak to api docs - setup right register for debug - add FAR_EL2 to debug exit structure - add support for trapping debug register access v3 - remove stray trace statement - fix spacing around operators (various) - clean-up usage of trap_debug - introduce debug_ptr, replace excessive memcpy stuff - don't use memcpy in ioctl, just assign - update cap ioctl documentation - reword a number comments - rename host_debug_state->external_debug_state v4 - use the new u32/u64 split debug_ptr approach - fix some wording/comments v5 - don't set MDSCR_EL1.KDE (not needed) v6 - update wording given change in commentary - KVM_GUESTDBG_USE_HW_BP->KVM_GUESTDBG_USE_HW v7 - fix merge conflicts from ioctl move to guest.c - use kvm_arm_reset_debug_ptr to reset ptr - a BUG_ON() test has been added to trap failure to reset debug_ptr - debugging->debug in kvm_host.h comment - s/defined// s/to// in commit msg - rm ref to introducing debug_ptr in commit msg - add r-b tag v8 - add #include to hw_breakpoint.h --- Documentation/virtual/kvm/api.txt | 7 +++++- arch/arm64/include/asm/hw_breakpoint.h | 14 ++++++++++++ arch/arm64/include/asm/kvm_host.h | 6 ++++- arch/arm64/kernel/hw_breakpoint.c | 12 ---------- arch/arm64/kvm/debug.c | 40 +++++++++++++++++++++++++++++----- arch/arm64/kvm/guest.c | 7 ++++++ arch/arm64/kvm/handle_exit.c | 6 +++++ arch/arm64/kvm/reset.c | 13 +++++++++++ include/uapi/linux/kvm.h | 2 ++ 9 files changed, 88 insertions(+), 19 deletions(-) diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt index 33c8143..ada57df 100644 --- a/Documentation/virtual/kvm/api.txt +++ b/Documentation/virtual/kvm/api.txt @@ -2668,7 +2668,7 @@ The top 16 bits of the control field are architecture specific control flags which can include the following: - KVM_GUESTDBG_USE_SW_BP: using software breakpoints [x86, arm64] - - KVM_GUESTDBG_USE_HW_BP: using hardware breakpoints [x86, s390] + - KVM_GUESTDBG_USE_HW_BP: using hardware breakpoints [x86, s390, arm64] - KVM_GUESTDBG_INJECT_DB: inject DB type exception [x86] - KVM_GUESTDBG_INJECT_BP: inject BP type exception [x86] - KVM_GUESTDBG_EXIT_PENDING: trigger an immediate guest exit [s390] @@ -2683,6 +2683,11 @@ updated to the correct (supplied) values. The second part of the structure is architecture specific and typically contains a set of debug registers. +For arm64 the number of debug registers is implementation defined and +can be determined by querying the KVM_CAP_GUEST_DEBUG_HW_BPS and +KVM_CAP_GUEST_DEBUG_HW_WPS capabilities which return a positive number +indicating the number of supported registers. + When debug events exit the main run loop with the reason KVM_EXIT_DEBUG with the kvm_debug_exit_arch part of the kvm_run structure containing architecture specific debug information. diff --git a/arch/arm64/include/asm/hw_breakpoint.h b/arch/arm64/include/asm/hw_breakpoint.h index 52b484b..4c47cb2 100644 --- a/arch/arm64/include/asm/hw_breakpoint.h +++ b/arch/arm64/include/asm/hw_breakpoint.h @@ -16,6 +16,8 @@ #ifndef __ASM_HW_BREAKPOINT_H #define __ASM_HW_BREAKPOINT_H +#include + #ifdef __KERNEL__ struct arch_hw_breakpoint_ctrl { @@ -132,5 +134,17 @@ static inline void ptrace_hw_copy_thread(struct task_struct *task) extern struct pmu perf_ops_bp; +/* Determine number of BRP registers available. */ +static inline int get_num_brps(void) +{ + return ((read_cpuid(ID_AA64DFR0_EL1) >> 12) & 0xf) + 1; +} + +/* Determine number of WRP registers available. */ +static inline int get_num_wrps(void) +{ + return ((read_cpuid(ID_AA64DFR0_EL1) >> 20) & 0xf) + 1; +} + #endif /* __KERNEL__ */ #endif /* __ASM_BREAKPOINT_H */ diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index 461d288..6c745e0 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -116,13 +116,17 @@ struct kvm_vcpu_arch { * debugging the guest from the host and to maintain separate host and * guest state during world switches. vcpu_debug_state are the debug * registers of the vcpu as the guest sees them. host_debug_state are - * the host registers which are saved and restored during world switches. + * the host registers which are saved and restored during + * world switches. external_debug_state contains the debug + * values we want to debug the guest. This is set via the + * KVM_SET_GUEST_DEBUG ioctl. * * debug_ptr points to the set of debug registers that should be loaded * onto the hardware when running the guest. */ struct kvm_guest_debug_arch *debug_ptr; struct kvm_guest_debug_arch vcpu_debug_state; + struct kvm_guest_debug_arch external_debug_state; /* Pointer to host CPU context */ kvm_cpu_context_t *host_cpu_context; diff --git a/arch/arm64/kernel/hw_breakpoint.c b/arch/arm64/kernel/hw_breakpoint.c index e7d934d..3a41bbf 100644 --- a/arch/arm64/kernel/hw_breakpoint.c +++ b/arch/arm64/kernel/hw_breakpoint.c @@ -49,18 +49,6 @@ static DEFINE_PER_CPU(int, stepping_kernel_bp); static int core_num_brps; static int core_num_wrps; -/* Determine number of BRP registers available. */ -static int get_num_brps(void) -{ - return ((read_cpuid(ID_AA64DFR0_EL1) >> 12) & 0xf) + 1; -} - -/* Determine number of WRP registers available. */ -static int get_num_wrps(void) -{ - return ((read_cpuid(ID_AA64DFR0_EL1) >> 20) & 0xf) + 1; -} - int hw_breakpoint_slots(int type) { /* diff --git a/arch/arm64/kvm/debug.c b/arch/arm64/kvm/debug.c index e0947b7..4a99e54 100644 --- a/arch/arm64/kvm/debug.c +++ b/arch/arm64/kvm/debug.c @@ -105,10 +105,6 @@ void kvm_arm_setup_debug(struct kvm_vcpu *vcpu) MDCR_EL2_TDRA | MDCR_EL2_TDOSA); - /* Trap on access to debug registers? */ - if (trap_debug) - vcpu->arch.mdcr_el2 |= MDCR_EL2_TDA; - /* Is Guest debugging in effect? */ if (vcpu->guest_debug) { /* Route all software debug exceptions to EL2 */ @@ -143,11 +139,45 @@ void kvm_arm_setup_debug(struct kvm_vcpu *vcpu) } else { vcpu_sys_reg(vcpu, MDSCR_EL1) &= ~DBG_MDSCR_SS; } + + /* + * HW Breakpoints and watchpoints + * + * We simply switch the debug_ptr to point to our new + * external_debug_state which has been populated by the + * debug ioctl. The existing KVM_ARM64_DEBUG_DIRTY + * mechanism ensures the registers are updated on the + * world switch. + */ + if (vcpu->guest_debug & KVM_GUESTDBG_USE_HW) { + /* Enable breakpoints/watchpoints */ + vcpu_sys_reg(vcpu, MDSCR_EL1) |= DBG_MDSCR_MDE; + + vcpu->arch.debug_ptr = &vcpu->arch.external_debug_state; + vcpu->arch.debug_flags |= KVM_ARM64_DEBUG_DIRTY; + trap_debug = true; + } } + + BUG_ON(!vcpu->guest_debug && + vcpu->arch.debug_ptr != &vcpu->arch.vcpu_debug_state); + + /* Trap debug register access */ + if (trap_debug) + vcpu->arch.mdcr_el2 |= MDCR_EL2_TDA; } void kvm_arm_clear_debug(struct kvm_vcpu *vcpu) { - if (vcpu->guest_debug) + if (vcpu->guest_debug) { restore_guest_debug_regs(vcpu); + + /* + * If we were using HW debug we need to restore the + * debug_ptr to the guest debug state. + */ + if (vcpu->guest_debug & KVM_GUESTDBG_USE_HW) + kvm_arm_reset_debug_ptr(vcpu); + + } } diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c index 48de4f4..6f1b249 100644 --- a/arch/arm64/kvm/guest.c +++ b/arch/arm64/kvm/guest.c @@ -334,6 +334,7 @@ int kvm_arch_vcpu_ioctl_translate(struct kvm_vcpu *vcpu, #define KVM_GUESTDBG_VALID_MASK (KVM_GUESTDBG_ENABLE | \ KVM_GUESTDBG_USE_SW_BP | \ + KVM_GUESTDBG_USE_HW | \ KVM_GUESTDBG_SINGLESTEP) /** @@ -354,6 +355,12 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu, if (dbg->control & KVM_GUESTDBG_ENABLE) { vcpu->guest_debug = dbg->control; + + /* Hardware assisted Break and Watch points */ + if (vcpu->guest_debug & KVM_GUESTDBG_USE_HW) { + vcpu->arch.external_debug_state = dbg->arch; + } + } else { /* If not enabled clear all flags */ vcpu->guest_debug = 0; diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c index e9de13e..68a0759 100644 --- a/arch/arm64/kvm/handle_exit.c +++ b/arch/arm64/kvm/handle_exit.c @@ -103,7 +103,11 @@ 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_WATCHPT_LOW: + run->debug.arch.far = vcpu->arch.fault.far_el2; + /* fall through */ case ESR_ELx_EC_SOFTSTP_LOW: + case ESR_ELx_EC_BREAKPT_LOW: case ESR_ELx_EC_BKPT32: case ESR_ELx_EC_BRK64: break; @@ -132,6 +136,8 @@ static exit_handle_fn arm_exit_handlers[] = { [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_WATCHPT_LOW]= kvm_handle_guest_debug, + [ESR_ELx_EC_BREAKPT_LOW]= kvm_handle_guest_debug, [ESR_ELx_EC_BKPT32] = kvm_handle_guest_debug, [ESR_ELx_EC_BRK64] = kvm_handle_guest_debug, }; diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c index 0b43265..8620926 100644 --- a/arch/arm64/kvm/reset.c +++ b/arch/arm64/kvm/reset.c @@ -22,6 +22,7 @@ #include #include #include +#include #include @@ -56,6 +57,12 @@ static bool cpu_has_32bit_el1(void) return !!(pfr0 & 0x20); } +/** + * kvm_arch_dev_ioctl_check_extension + * + * We currently assume that the number of HW registers is uniform + * across all CPUs (see cpuinfo_sanity_check). + */ int kvm_arch_dev_ioctl_check_extension(long ext) { int r; @@ -64,6 +71,12 @@ int kvm_arch_dev_ioctl_check_extension(long ext) case KVM_CAP_ARM_EL1_32BIT: r = cpu_has_32bit_el1(); break; + case KVM_CAP_GUEST_DEBUG_HW_BPS: + r = get_num_brps(); + break; + case KVM_CAP_GUEST_DEBUG_HW_WPS: + r = get_num_wrps(); + break; default: r = 0; } diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index 70ac641..f020dd0 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -817,6 +817,8 @@ struct kvm_ppc_smmu_info { #define KVM_CAP_S390_INJECT_IRQ 113 #define KVM_CAP_S390_IRQ_STATE 114 #define KVM_CAP_PPC_HWRNG 115 +#define KVM_CAP_GUEST_DEBUG_HW_BPS 116 +#define KVM_CAP_GUEST_DEBUG_HW_WPS 117 #ifdef KVM_CAP_IRQ_ROUTING