From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?UTF-8?q?Alex=20Benn=C3=A9e?= Subject: [PATCH 5/7] KVM: arm64: guest debug, add support for single-step Date: Tue, 25 Nov 2014 16:10:03 +0000 Message-ID: <1416931805-23223-6-git-send-email-alex.bennee@linaro.org> References: <1416931805-23223-1-git-send-email-alex.bennee@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <1416931805-23223-1-git-send-email-alex.bennee@linaro.org> Sender: kvm-owner@vger.kernel.org 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 Cc: jan.kiszka@siemens.com, dahi@linux.vnet.ibm.com, r65777@freescale.com, bp@suse.de, pbonzini@redhat.com, =?UTF-8?q?Alex=20Benn=C3=A9e?= , Gleb Natapov , Russell King , Catalin Marinas , Will Deacon , Lorenzo Pieralisi , open list , "open list:ABI/API" List-Id: linux-api@vger.kernel.org This adds support for single-stepping the guest. As userspace can and will manipulate guest registers before restarting any tweaking of the registers has to occur just before control is passed back to the guest. =46urthermore while guest debugging is in effect we need to squash the ability of the guest to single-step itself as we have no easy way of re-entering the guest after the exception has been delivered to the hypervisor. Signed-off-by: Alex Benn=C3=A9e diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c index 48d26bb..a76daae 100644 --- a/arch/arm/kvm/arm.c +++ b/arch/arm/kvm/arm.c @@ -38,6 +38,7 @@ #include #include #include +#include #include #include #include @@ -300,6 +301,17 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu) kvm_arm_set_running_vcpu(NULL); } =20 +/** + * kvm_arch_vcpu_ioctl_set_guest_debug - Setup guest debugging + * @kvm: pointer to the KVM struct + * @kvm_guest_debug: the ioctl data buffer + * + * This sets up the VM for guest debugging. Care has to be taken when + * manipulating guest registers as these will be set/cleared by the + * hyper-visor controller, typically before each kvm_run event. As a + * result modification of the guest registers needs to take place + * after they have been restored in the hyp.S trampoline code. + */ int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu, struct kvm_guest_debug *dbg) { @@ -317,8 +329,8 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_= vcpu *vcpu, =20 /* Single Step */ if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) { - kvm_info("SS requested, not yet implemented\n"); - return -EINVAL; + kvm_info("SS requested\n"); + route_el2 =3D true; } =20 /* Software Break Points */ diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-of= fsets.c index 8da1043..78e5ae1 100644 --- a/arch/arm64/kernel/asm-offsets.c +++ b/arch/arm64/kernel/asm-offsets.c @@ -121,6 +121,7 @@ int main(void) DEFINE(VCPU_FAR_EL2, offsetof(struct kvm_vcpu, arch.fault.far_el2))= ; DEFINE(VCPU_HPFAR_EL2, offsetof(struct kvm_vcpu, arch.fault.hpfar_el= 2)); DEFINE(VCPU_DEBUG_FLAGS, offsetof(struct kvm_vcpu, arch.debug_flags)= ); + DEFINE(GUEST_DEBUG, offsetof(struct kvm_vcpu, guest_debug)); DEFINE(VCPU_HCR_EL2, offsetof(struct kvm_vcpu, arch.hcr_el2)); DEFINE(VCPU_MDCR_EL2, offsetof(struct kvm_vcpu, arch.mdcr_el2)); DEFINE(VCPU_IRQ_LINES, offsetof(struct kvm_vcpu, arch.irq_lines)); diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.= c index 28dc92b..6def054 100644 --- a/arch/arm64/kvm/handle_exit.c +++ b/arch/arm64/kvm/handle_exit.c @@ -91,6 +91,25 @@ static int kvm_handle_bkpt(struct kvm_vcpu *vcpu, st= ruct kvm_run *run) return 0; } =20 +/** + * kvm_handle_ss - handle single step exceptions + * + * @vcpu: the vcpu pointer + * + * See: ARM ARM D2.12 for the details. While the host is routing debug + * exceptions to it's handlers we have to suppress the ability of the + * guest to trigger exceptions. + */ +static int kvm_handle_ss(struct kvm_vcpu *vcpu, struct kvm_run *run) +{ + WARN_ON(!(vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP)); + + run->exit_reason =3D KVM_EXIT_DEBUG; + run->debug.arch.exit_type =3D KVM_DEBUG_EXIT_SINGLE_STEP; + run->debug.arch.address =3D *vcpu_pc(vcpu); + return 0; +} + static exit_handle_fn arm_exit_handlers[] =3D { [ESR_EL2_EC_WFI] =3D kvm_handle_wfx, [ESR_EL2_EC_CP15_32] =3D kvm_handle_cp15_32, @@ -105,6 +124,7 @@ static exit_handle_fn arm_exit_handlers[] =3D { [ESR_EL2_EC_SYS64] =3D kvm_handle_sys_reg, [ESR_EL2_EC_IABT] =3D kvm_handle_guest_abort, [ESR_EL2_EC_DABT] =3D kvm_handle_guest_abort, + [ESR_EL2_EC_SOFTSTP] =3D kvm_handle_ss, [ESR_EL2_EC_BKPT32] =3D kvm_handle_bkpt, [ESR_EL2_EC_BRK64] =3D kvm_handle_bkpt, }; diff --git a/arch/arm64/kvm/hyp.S b/arch/arm64/kvm/hyp.S index 3c733ea..c0bc218 100644 --- a/arch/arm64/kvm/hyp.S +++ b/arch/arm64/kvm/hyp.S @@ -16,6 +16,7 @@ */ =20 #include +#include =20 #include #include @@ -168,6 +169,31 @@ // x19-x29, lr, sp*, elr*, spsr* restore_common_regs =20 + // After restoring the guest registers but before we return to the gu= est + // we may want to make some final tweaks to support guest debugging. + ldr x3, [x0, #GUEST_DEBUG] + tbz x3, #KVM_GUESTDBG_ENABLE_SHIFT, 2f // No guest debug + + // x0 - preserved as VCPU ptr + // x1 - spsr + // x2 - mdscr + mrs x1, spsr_el2 + mrs x2, mdscr_el1 + + // See ARM ARM D2.12.3 The software step state machine + // If we are doing Single Step - set MDSCR_EL1.SS and PSTATE.SS + orr x1, x1, #DBG_SPSR_SS + orr x2, x2, #DBG_MDSCR_SS + tbnz x3, #KVM_GUESTDBG_SINGLESTEP_SHIFT, 1f + // If we are not doing Single Step we want to prevent the guest doing= so + // as otherwise we will have to deal with the re-routed exceptions as= we + // are doing other guest debug related things + eor x1, x1, #DBG_SPSR_SS + eor x2, x2, #DBG_MDSCR_SS +1: + msr spsr_el2, x1 + msr mdscr_el1, x2 +2: // Last bits of the 64bit state pop x2, x3 pop x0, x1 diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index 523f476..347e5b0 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -7,6 +7,8 @@ * Note: you must update KVM_API_VERSION if you change this interface. */ =20 +#ifndef __ASSEMBLY__ + #include #include #include @@ -515,11 +517,6 @@ struct kvm_s390_irq { } u; }; =20 -/* for KVM_SET_GUEST_DEBUG */ - -#define KVM_GUESTDBG_ENABLE 0x00000001 -#define KVM_GUESTDBG_SINGLESTEP 0x00000002 - struct kvm_guest_debug { __u32 control; __u32 pad; @@ -1189,4 +1186,15 @@ struct kvm_assigned_msix_entry { __u16 padding[3]; }; =20 +#endif /* __ASSEMBLY__ */ + +/* for KVM_SET_GUEST_DEBUG */ + +#define KVM_GUESTDBG_ENABLE_SHIFT 0 +#define KVM_GUESTDBG_ENABLE (1 << KVM_GUESTDBG_ENABLE_SHIFT) +#define KVM_GUESTDBG_SINGLESTEP_SHIFT 1 +#define KVM_GUESTDBG_SINGLESTEP (1 << KVM_GUESTDBG_SINGLESTEP_SHIFT) + + + #endif /* __LINUX_KVM_H */ --=20 2.1.3