From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoffer Dall Subject: Re: [PATCH v3 06/12] KVM: arm64: guest debug, add SW break point support Date: Fri, 8 May 2015 13:52:34 +0200 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-Transfer-Encoding: quoted-printable Cc: Russell King , kvm@vger.kernel.org, Jonathan Corbet , marc.zyngier@arm.com, jan.kiszka@siemens.com, "open list:DOCUMENTATION" , Will Deacon , open list , dahi@linux.vnet.ibm.com, Catalin Marinas , zhichao.huang@linaro.org, r65777@freescale.com, pbonzini@redhat.com, bp@suse.de, Gleb Natapov , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org To: Alex =?iso-8859-1?Q?Benn=E9e?= Return-path: Content-Disposition: inline In-Reply-To: <1430929407-3487-7-git-send-email-alex.bennee@linaro.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu List-Id: kvm.vger.kernel.org On Wed, May 06, 2015 at 05:23:21PM +0100, Alex Benn=E9e 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=E9e > = > --- > 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/kv= m/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 &=3D ~MDCR_EL2_TDA; > = > + /* Trap breakpoints? */ > + if (vcpu->guest_debug & KVM_GUESTDBG_USE_SW_BP) > + vcpu->arch.mdcr_el2 |=3D MDCR_EL2_TDE; > + else > + vcpu->arch.mdcr_el2 &=3D ~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, struc= t 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 =3D kvm_vcpu_get_hsr(vcpu); > + int ret =3D 0; > + > + run->exit_reason =3D KVM_EXIT_DEBUG; > + run->debug.arch.hsr =3D 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 =3D -1; > + break; > + } > + > + return ret; > +} > + > static exit_handle_fn arm_exit_handlers[] =3D { > [ESR_ELx_EC_WFx] =3D kvm_handle_wfx, > [ESR_ELx_EC_CP15_32] =3D kvm_handle_cp15_32, > @@ -96,6 +130,8 @@ static exit_handle_fn arm_exit_handlers[] =3D { > [ESR_ELx_EC_SYS64] =3D kvm_handle_sys_reg, > [ESR_ELx_EC_IABT_LOW] =3D kvm_handle_guest_abort, > [ESR_ELx_EC_DABT_LOW] =3D kvm_handle_guest_abort, > + [ESR_ELx_EC_BKPT32] =3D kvm_handle_guest_debug, > + [ESR_ELx_EC_BRK64] =3D 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