Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752851AbbEHLwk (ORCPT ); Fri, 8 May 2015 07:52:40 -0400 Received: from mail-lb0-f179.google.com ([209.85.217.179]:36092 "EHLO mail-lb0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752813AbbEHLwc (ORCPT ); Fri, 8 May 2015 07:52:32 -0400 Date: Fri, 8 May 2015 13:52:34 +0200 From: Christoffer Dall To: Alex =?iso-8859-1?Q?Benn=E9e?= Cc: kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, marc.zyngier@arm.com, peter.maydell@linaro.org, agraf@suse.de, drjones@redhat.com, pbonzini@redhat.com, zhichao.huang@linaro.org, jan.kiszka@siemens.com, dahi@linux.vnet.ibm.com, r65777@freescale.com, bp@suse.de, Gleb Natapov , Jonathan Corbet , Russell King , Catalin Marinas , Will Deacon , "open list:DOCUMENTATION" , open list Subject: Re: [PATCH v3 06/12] KVM: arm64: guest debug, add SW break point support Message-ID: <20150508115234.GF24744@cbox> References: <1430929407-3487-1-git-send-email-alex.bennee@linaro.org> <1430929407-3487-7-git-send-email-alex.bennee@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1430929407-3487-7-git-send-email-alex.bennee@linaro.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5148 Lines: 144 On Wed, May 06, 2015 at 05:23:21PM +0100, Alex Benn?e wrote: > This adds support for SW breakpoints inserted by userspace. > > We do this by trapping all guest software debug exceptions to the > hypervisor (MDCR_EL2.TDE). The exit handler sets an exit reason of > KVM_EXIT_DEBUG with the kvm_debug_exit_arch structure holding the > exception syndrome information. > > It will be up to userspace to extract the PC (via GET_ONE_REG) and > determine if the debug event was for a breakpoint it inserted. If not > userspace will need to re-inject the correct exception restart the > hypervisor to deliver the debug exception to the guest. > > Any other guest software debug exception (e.g. single step or HW > assisted breakpoints) will cause an error and the VM to be killed. This > is addressed by later patches which add support for the other debug > types. > > Signed-off-by: Alex Benn?e > > --- > v2 > - update to use new exit struct > - tweak for C setup > - do our setup in debug_setup/clear code > - fixed up comments > v3: > - fix spacing in KVM_GUESTDBG_VALID_MASK > - fix and clarify wording on kvm_handle_guest_debug > - handle error case in kvm_handle_guest_debug > - re-word the commit message > > diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt > index 4b0132f..5ef937c 100644 > --- a/Documentation/virtual/kvm/api.txt > +++ b/Documentation/virtual/kvm/api.txt > @@ -2667,7 +2667,7 @@ when running. Common control bits are: > 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] > + - KVM_GUESTDBG_USE_SW_BP: using software breakpoints [x86, arm64] > - KVM_GUESTDBG_USE_HW_BP: using hardware breakpoints [x86, s390] > - KVM_GUESTDBG_INJECT_DB: inject DB type exception [x86] > - KVM_GUESTDBG_INJECT_BP: inject BP type exception [x86] > diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c > index 4a274e1..064c105 100644 > --- a/arch/arm/kvm/arm.c > +++ b/arch/arm/kvm/arm.c > @@ -302,7 +302,7 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu) > kvm_arm_set_running_vcpu(NULL); > } > > -#define KVM_GUESTDBG_VALID_MASK (KVM_GUESTDBG_ENABLE) > +#define KVM_GUESTDBG_VALID_MASK (KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_SW_BP) > > /** > * kvm_arch_vcpu_ioctl_set_guest_debug - set up guest debugging > diff --git a/arch/arm64/kvm/debug.c b/arch/arm64/kvm/debug.c > index b1f8731..5bee676 100644 > --- a/arch/arm64/kvm/debug.c > +++ b/arch/arm64/kvm/debug.c > @@ -75,6 +75,12 @@ void kvm_arm_setup_debug(struct kvm_vcpu *vcpu) > else > vcpu->arch.mdcr_el2 &= ~MDCR_EL2_TDA; > > + /* Trap breakpoints? */ > + if (vcpu->guest_debug & KVM_GUESTDBG_USE_SW_BP) > + vcpu->arch.mdcr_el2 |= MDCR_EL2_TDE; > + else > + vcpu->arch.mdcr_el2 &= ~MDCR_EL2_TDE; > + I also don't think you need the else-clause here. > } > > void kvm_arm_clear_debug(struct kvm_vcpu *vcpu) > diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c > index 524fa25..27f38a9 100644 > --- a/arch/arm64/kvm/handle_exit.c > +++ b/arch/arm64/kvm/handle_exit.c > @@ -82,6 +82,40 @@ static int kvm_handle_wfx(struct kvm_vcpu *vcpu, struct kvm_run *run) > return 1; > } > > +/** > + * kvm_handle_guest_debug - handle a debug exception instruction > + * > + * @vcpu: the vcpu pointer > + * @run: access to the kvm_run structure for results > + * > + * We route all debug exceptions through the same handler. If both the > + * guest and host are using the same debug facilities it will be up to > + * userspace to re-inject the correct exception for guest delivery. > + * > + * @return: 0 (while setting run->exit_reason), -1 for error > + */ > +static int kvm_handle_guest_debug(struct kvm_vcpu *vcpu, struct kvm_run *run) > +{ > + u32 hsr = kvm_vcpu_get_hsr(vcpu); > + int ret = 0; > + > + run->exit_reason = KVM_EXIT_DEBUG; > + run->debug.arch.hsr = hsr; > + > + switch (hsr >> ESR_ELx_EC_SHIFT) { > + case ESR_ELx_EC_BKPT32: > + case ESR_ELx_EC_BRK64: > + break; > + default: > + kvm_err("%s: un-handled case hsr: %#08x\n", > + __func__, (unsigned int) hsr); > + ret = -1; > + break; > + } > + > + return ret; > +} > + > static exit_handle_fn arm_exit_handlers[] = { > [ESR_ELx_EC_WFx] = kvm_handle_wfx, > [ESR_ELx_EC_CP15_32] = kvm_handle_cp15_32, > @@ -96,6 +130,8 @@ 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_BKPT32] = kvm_handle_guest_debug, > + [ESR_ELx_EC_BRK64] = kvm_handle_guest_debug, > }; > > static exit_handle_fn kvm_get_exit_handler(struct kvm_vcpu *vcpu) > -- > 2.3.5 > Besides the nit: Reviewed-by: Christoffer Dall -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/