From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx2.suse.de (cantor2.suse.de [195.135.220.15]) (using TLSv1 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id CA5661A0004 for ; Thu, 3 Jul 2014 21:51:40 +1000 (EST) Message-ID: <53B543C5.0@suse.de> Date: Thu, 03 Jul 2014 13:51:33 +0200 From: Alexander Graf MIME-Version: 1.0 To: Madhavan Srinivasan , benh@kernel.crashing.org, paulus@samba.org Subject: Re: [PATCH v2] powerpc/kvm: support to handle sw breakpoint References: <1404204062-19635-1-git-send-email-maddy@linux.vnet.ibm.com> In-Reply-To: <1404204062-19635-1-git-send-email-maddy@linux.vnet.ibm.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Cc: linuxppc-dev@lists.ozlabs.org, kvm@vger.kernel.org, kvm-ppc@vger.kernel.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 01.07.14 10:41, Madhavan Srinivasan wrote: > This patch adds kernel side support for software breakpoint. > Design is that, by using an illegal instruction, we trap to hypervisor > via Emulation Assistance interrupt, where we check for the illegal instruction > and accordingly we return to Host or Guest. Patch also adds support for > software breakpoint in PR KVM. > > Patch mandates use of "abs" instruction as sw breakpoint instruction > (primary opcode 31 and extended opcode 360). Based on PowerISA v2.01, > ABS instruction has been dropped from the architecture and treated an > illegal instruction. > > Changes v1->v2: > > Moved the debug instruction #def to kvm_book3s.h. This way PR_KVM can also share it. > Added code to use KVM get one reg infrastructure to get debug opcode. > Updated emulate.c to include emulation of debug instruction incase of PR_KVM. > Made changes to commit message. > > Signed-off-by: Madhavan Srinivasan > --- > arch/powerpc/include/asm/kvm_book3s.h | 8 ++++++++ > arch/powerpc/include/asm/ppc-opcode.h | 5 +++++ > arch/powerpc/kvm/book3s.c | 3 ++- > arch/powerpc/kvm/book3s_hv.c | 9 +++++++++ > arch/powerpc/kvm/book3s_pr.c | 3 +++ > arch/powerpc/kvm/emulate.c | 10 ++++++++++ > 6 files changed, 37 insertions(+), 1 deletion(-) > > diff --git a/arch/powerpc/include/asm/kvm_book3s.h b/arch/powerpc/include/asm/kvm_book3s.h > index f52f656..180d549 100644 > --- a/arch/powerpc/include/asm/kvm_book3s.h > +++ b/arch/powerpc/include/asm/kvm_book3s.h > @@ -24,6 +24,14 @@ > #include > #include > > +/* > + * KVMPPC_INST_BOOK3S_DEBUG is debug Instruction for supporting Software Breakpoint. > + * Instruction mnemonic is ABS, primary opcode is 31 and extended opcode is 360. > + * Based on PowerISA v2.01, ABS instruction has been dropped from the architecture > + * and treated an illegal instruction. > + */ > +#define KVMPPC_INST_BOOK3S_DEBUG 0x7c0002d0 This will still break with LE guests. > + > struct kvmppc_bat { > u64 raw; > u32 bepi; > diff --git a/arch/powerpc/include/asm/ppc-opcode.h b/arch/powerpc/include/asm/ppc-opcode.h > index 3132bb9..3fbb4c1 100644 > --- a/arch/powerpc/include/asm/ppc-opcode.h > +++ b/arch/powerpc/include/asm/ppc-opcode.h > @@ -111,6 +111,11 @@ > #define OP_31_XOP_LHBRX 790 > #define OP_31_XOP_STHBRX 918 > > +/* KVMPPC_INST_BOOK3S_DEBUG -- Software breakpoint Instruction > + * Instruction mnemonic is ABS, primary opcode is 31 and extended opcode is 360. > + */ > +#define OP_31_XOP_ABS 360 > + > #define OP_LWZ 32 > #define OP_LD 58 > #define OP_LWZU 33 > diff --git a/arch/powerpc/kvm/book3s.c b/arch/powerpc/kvm/book3s.c > index c254c27..b40fe5d 100644 > --- a/arch/powerpc/kvm/book3s.c > +++ b/arch/powerpc/kvm/book3s.c > @@ -789,7 +789,8 @@ int kvm_arch_vcpu_ioctl_translate(struct kvm_vcpu *vcpu, > int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu, > struct kvm_guest_debug *dbg) > { > - return -EINVAL; > + vcpu->guest_debug = dbg->control; > + return 0; > } > > void kvmppc_decrementer_func(unsigned long data) > diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c > index 7a12edb..402c1ec 100644 > --- a/arch/powerpc/kvm/book3s_hv.c > +++ b/arch/powerpc/kvm/book3s_hv.c > @@ -725,8 +725,14 @@ static int kvmppc_handle_exit_hv(struct kvm_run *run, struct kvm_vcpu *vcpu, > * we don't emulate any guest instructions at this stage. > */ > case BOOK3S_INTERRUPT_H_EMUL_ASSIST: > + if (kvmppc_get_last_inst(vcpu) == KVMPPC_INST_BOOK3S_DEBUG ) { > + run->exit_reason = KVM_EXIT_DEBUG; > + run->debug.arch.address = kvmppc_get_pc(vcpu); > + r = RESUME_HOST; Phew - why can't we just go into the normal instruction emulator for EMUL_ASSIST? Alex