| Message ID | 1406868643-26291-1-git-send-email-maddy@linux.vnet.ibm.com (mailing list archive) |
|---|---|
| State | Superseded, archived |
| Headers | show |
> +/* > + * KVMPPC_INST_BOOK3S_DEBUG is debug Instruction for supporting Software Breakpoint. > + * Based on PowerISA v2.07, Instruction with opcode 0s will be treated as illegal > + * instruction. > + */ "primary opcode 0" instead? > +#define OP_ZERO 0x0 Using 0x0 where you mean 0, making a #define for 0 in the first place... This all looks rather silly doesn't it. > + case OP_ZERO: > + if((inst & 0x00FFFF00) == KVMPPC_INST_BOOK3S_DEBUG) { You either shouldn't mask at all here, or the mask is wrong (the primary op is the top six bits, not the top eight). Segher
On Sunday 03 August 2014 09:21 PM, Segher Boessenkool wrote: >> +/* >> + * KVMPPC_INST_BOOK3S_DEBUG is debug Instruction for supporting Software Breakpoint. >> + * Based on PowerISA v2.07, Instruction with opcode 0s will be treated as illegal >> + * instruction. >> + */ > > "primary opcode 0" instead? > ok sure. >> +#define OP_ZERO 0x0 > > Using 0x0 where you mean 0, making a #define for 0 in the first place... > This all looks rather silly doesn't it. > I wanted to avoid zero mentioned in the case statement, but can add a comment explaining it. >> + case OP_ZERO: >> + if((inst & 0x00FFFF00) == KVMPPC_INST_BOOK3S_DEBUG) { > > You either shouldn't mask at all here, or the mask is wrong (the primary > op is the top six bits, not the top eight). > Yes. I guess I dont need to check here. Will resend the patch. Thanks for review Regards Maddy > > Segher >
On 01.08.14 06:50, 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. > > Changes v2->v3: > Changed the debug instructions. Using the all zero opcode in the instruction word > as illegal instruction as mentioned in Power ISA instead of ABS > Removed reg updated in emulation assist and added a call to > kvmppc_emulate_instruction for reg update. > > 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 <maddy@linux.vnet.ibm.com> > --- > arch/powerpc/include/asm/kvm_book3s.h | 7 +++++++ > arch/powerpc/include/asm/ppc-opcode.h | 5 +++++ > arch/powerpc/kvm/book3s.c | 3 ++- > arch/powerpc/kvm/book3s_hv.c | 12 ++++++++++-- > arch/powerpc/kvm/book3s_pr.c | 3 +++ > arch/powerpc/kvm/emulate.c | 9 +++++++++ > 6 files changed, 36 insertions(+), 3 deletions(-) > > diff --git a/arch/powerpc/include/asm/kvm_book3s.h b/arch/powerpc/include/asm/kvm_book3s.h > index f52f656..f17e3fd 100644 > --- a/arch/powerpc/include/asm/kvm_book3s.h > +++ b/arch/powerpc/include/asm/kvm_book3s.h > @@ -24,6 +24,13 @@ > #include <linux/kvm_host.h> > #include <asm/kvm_book3s_asm.h> > > +/* > + * KVMPPC_INST_BOOK3S_DEBUG is debug Instruction for supporting Software Breakpoint. > + * Based on PowerISA v2.07, Instruction with opcode 0s will be treated as illegal > + * instruction. > + */ > +#define KVMPPC_INST_BOOK3S_DEBUG 0x00dddd00 > + > 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..56739b3 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 > + * 0x00dddd00 -- Primary opcode is 0s > + */ > +#define OP_ZERO 0x0 > + > #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..7c16f4f 100644 > --- a/arch/powerpc/kvm/book3s_hv.c > +++ b/arch/powerpc/kvm/book3s_hv.c > @@ -725,8 +725,13 @@ 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: > - kvmppc_core_queue_program(vcpu, SRR1_PROGILL); > - r = RESUME_GUEST; > + if (kvmppc_get_last_inst(vcpu) == KVMPPC_INST_BOOK3S_DEBUG) { > + kvmppc_emulate_instruction(run, vcpu); I changed the emulation code flow very recently, so while I advised you to write it this way this won't work with recent git versions anymore :(. Please just create a tiny static function that handles this particular inst and duplicate the logic in book3s_emulate.c (for PR) as well as here (for HV). > + r = RESUME_HOST; > + } else { > + kvmppc_core_queue_program(vcpu, SRR1_PROGILL); > + r = RESUME_GUEST; > + } > break; > /* > * This occurs if the guest (kernel or userspace), does something that > @@ -831,6 +836,9 @@ static int kvmppc_get_one_reg_hv(struct kvm_vcpu *vcpu, u64 id, > long int i; > > switch (id) { > + case KVM_REG_PPC_DEBUG_INST: > + *val = get_reg_val(id, KVMPPC_INST_BOOK3S_DEBUG); > + break; > case KVM_REG_PPC_HIOR: > *val = get_reg_val(id, 0); > break; > diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c > index 8eef1e5..27f5234 100644 > --- a/arch/powerpc/kvm/book3s_pr.c > +++ b/arch/powerpc/kvm/book3s_pr.c > @@ -1229,6 +1229,9 @@ static int kvmppc_get_one_reg_pr(struct kvm_vcpu *vcpu, u64 id, > int r = 0; > > switch (id) { > + case KVM_REG_PPC_DEBUG_INST: > + *val = get_reg_val(id, KVMPPC_INST_BOOK3S_DEBUG); > + break; > case KVM_REG_PPC_HIOR: > *val = get_reg_val(id, to_book3s(vcpu)->hior); > break; > diff --git a/arch/powerpc/kvm/emulate.c b/arch/powerpc/kvm/emulate.c > index da86d9b..d95014e 100644 > --- a/arch/powerpc/kvm/emulate.c > +++ b/arch/powerpc/kvm/emulate.c This should be book3s_emulate.c. Alex
On Mon, 2014-08-11 at 09:26 +0200, Alexander Graf wrote: > > diff --git a/arch/powerpc/kvm/emulate.c b/arch/powerpc/kvm/emulate.c > > index da86d9b..d95014e 100644 > > --- a/arch/powerpc/kvm/emulate.c > > +++ b/arch/powerpc/kvm/emulate.c > > This should be book3s_emulate.c. Any reason we can't make that 00dddd00 opcode as breakpoint common to all powerpc variants ? Cheers, Ben.
On 11.08.14 10:51, Benjamin Herrenschmidt wrote: > On Mon, 2014-08-11 at 09:26 +0200, Alexander Graf wrote: >>> diff --git a/arch/powerpc/kvm/emulate.c b/arch/powerpc/kvm/emulate.c >>> index da86d9b..d95014e 100644 >>> --- a/arch/powerpc/kvm/emulate.c >>> +++ b/arch/powerpc/kvm/emulate.c >> This should be book3s_emulate.c. > Any reason we can't make that 00dddd00 opcode as breakpoint common to > all powerpc variants ? I can't think of a good reason. We use a hypercall on booke (which traps into an illegal instruction for pr) today, but I don't think it has to be that way. Given that the user space API allows us to change it dynamically, there should be nothing blocking us from going with 00dddd00 always. Alex
On Monday 11 August 2014 02:45 PM, Alexander Graf wrote: > > On 11.08.14 10:51, Benjamin Herrenschmidt wrote: >> On Mon, 2014-08-11 at 09:26 +0200, Alexander Graf wrote: >>>> diff --git a/arch/powerpc/kvm/emulate.c b/arch/powerpc/kvm/emulate.c >>>> index da86d9b..d95014e 100644 >>>> --- a/arch/powerpc/kvm/emulate.c >>>> +++ b/arch/powerpc/kvm/emulate.c >>> This should be book3s_emulate.c. >> Any reason we can't make that 00dddd00 opcode as breakpoint common to >> all powerpc variants ? > > I can't think of a good reason. We use a hypercall on booke (which traps > into an illegal instruction for pr) today, but I don't think it has to > be that way. > > Given that the user space API allows us to change it dynamically, there > should be nothing blocking us from going with 00dddd00 always. > Kindly correct me if i am wrong. So we can still have a common code in emulate.c to set the env for both HV and pr incase of illegal instruction (i will rebase latest src). But suggestion here to use 00dddd00, in that case current path in embed is kvmppc_handle_exit (booke.c) -> BOOKE_INTERRUPT_HV_PRIV -> emulation_exit -> kvmppc_emulate_instruction, will change to kvmppc_handle_exit (booke.c) -> BOOKE_INTERRUPT_PROGRAM -> if debug instr call emulation_exit else send to guest? Thanks for review regards Maddy > > Alex >
On 12.08.14 07:17, Madhavan Srinivasan wrote: > On Monday 11 August 2014 02:45 PM, Alexander Graf wrote: >> On 11.08.14 10:51, Benjamin Herrenschmidt wrote: >>> On Mon, 2014-08-11 at 09:26 +0200, Alexander Graf wrote: >>>>> diff --git a/arch/powerpc/kvm/emulate.c b/arch/powerpc/kvm/emulate.c >>>>> index da86d9b..d95014e 100644 >>>>> --- a/arch/powerpc/kvm/emulate.c >>>>> +++ b/arch/powerpc/kvm/emulate.c >>>> This should be book3s_emulate.c. >>> Any reason we can't make that 00dddd00 opcode as breakpoint common to >>> all powerpc variants ? >> I can't think of a good reason. We use a hypercall on booke (which traps >> into an illegal instruction for pr) today, but I don't think it has to >> be that way. >> >> Given that the user space API allows us to change it dynamically, there >> should be nothing blocking us from going with 00dddd00 always. >> > Kindly correct me if i am wrong. So we can still have a common code in > emulate.c to set the env for both HV and pr incase of illegal > instruction (i will rebase latest src). But suggestion here to use > 00dddd00, in that case current path in embed is kvmppc_handle_exit > (booke.c) -> BOOKE_INTERRUPT_HV_PRIV -> emulation_exit -> > kvmppc_emulate_instruction, will change to kvmppc_handle_exit (booke.c) > -> BOOKE_INTERRUPT_PROGRAM -> if debug instr call emulation_exit else > send to guest? I can't follow your description above. With the latest git version HV KVM does not include emulate.c anymore. Also, it would make a lot of sense of have the same soft breakpoint instruction across all ppc targets, so it would make sense to change it to 0x00dddd00 for booke as well. Basically you would have handling code in emulate.c and book3s_hv.c at the end of the day. Alex
On Tuesday 12 August 2014 04:49 PM, Alexander Graf wrote: > > On 12.08.14 07:17, Madhavan Srinivasan wrote: >> On Monday 11 August 2014 02:45 PM, Alexander Graf wrote: >>> On 11.08.14 10:51, Benjamin Herrenschmidt wrote: >>>> On Mon, 2014-08-11 at 09:26 +0200, Alexander Graf wrote: >>>>>> diff --git a/arch/powerpc/kvm/emulate.c b/arch/powerpc/kvm/emulate.c >>>>>> index da86d9b..d95014e 100644 >>>>>> --- a/arch/powerpc/kvm/emulate.c >>>>>> +++ b/arch/powerpc/kvm/emulate.c >>>>> This should be book3s_emulate.c. >>>> Any reason we can't make that 00dddd00 opcode as breakpoint common to >>>> all powerpc variants ? >>> I can't think of a good reason. We use a hypercall on booke (which traps >>> into an illegal instruction for pr) today, but I don't think it has to >>> be that way. >>> >>> Given that the user space API allows us to change it dynamically, there >>> should be nothing blocking us from going with 00dddd00 always. >>> >> Kindly correct me if i am wrong. So we can still have a common code in >> emulate.c to set the env for both HV and pr incase of illegal >> instruction (i will rebase latest src). But suggestion here to use >> 00dddd00, in that case current path in embed is kvmppc_handle_exit >> (booke.c) -> BOOKE_INTERRUPT_HV_PRIV -> emulation_exit -> >> kvmppc_emulate_instruction, will change to kvmppc_handle_exit (booke.c) >> -> BOOKE_INTERRUPT_PROGRAM -> if debug instr call emulation_exit else >> send to guest? > > I can't follow your description above. > My bad. > With the latest git version HV KVM does not include emulate.c anymore. > > Also, it would make a lot of sense of have the same soft breakpoint > instruction across all ppc targets, so it would make sense to change it > to 0x00dddd00 for booke as well. > Got it. Was describing the current control flow with respect to booke and where changes needed (for same software breakpoint inst). This is for my understanding and wanted verify. kvmppc_handle_exit(booke.c) -> BOOKE_INTERRUPT_HV_PRIV -> emulation_exit ->kvmppc_emulate_instruction Incase of using the same software breakpoint instruction (0x00dddd00), then we need to add code in booke something like this kvmppc_handle_exit (booke.c) -> BOOKE_INTERRUPT_PROGRAM -> if debug instr ->emulation_exit else ->send to guest? > Basically you would have handling code in emulate.c and book3s_hv.c at > the end of the day. > Yes. Will resend the patch with updated code. > > Alex >
diff --git a/arch/powerpc/include/asm/kvm_book3s.h b/arch/powerpc/include/asm/kvm_book3s.h index f52f656..f17e3fd 100644 --- a/arch/powerpc/include/asm/kvm_book3s.h +++ b/arch/powerpc/include/asm/kvm_book3s.h @@ -24,6 +24,13 @@ #include <linux/kvm_host.h> #include <asm/kvm_book3s_asm.h> +/* + * KVMPPC_INST_BOOK3S_DEBUG is debug Instruction for supporting Software Breakpoint. + * Based on PowerISA v2.07, Instruction with opcode 0s will be treated as illegal + * instruction. + */ +#define KVMPPC_INST_BOOK3S_DEBUG 0x00dddd00 + 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..56739b3 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 + * 0x00dddd00 -- Primary opcode is 0s + */ +#define OP_ZERO 0x0 + #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..7c16f4f 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -725,8 +725,13 @@ 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: - kvmppc_core_queue_program(vcpu, SRR1_PROGILL); - r = RESUME_GUEST; + if (kvmppc_get_last_inst(vcpu) == KVMPPC_INST_BOOK3S_DEBUG) { + kvmppc_emulate_instruction(run, vcpu); + r = RESUME_HOST; + } else { + kvmppc_core_queue_program(vcpu, SRR1_PROGILL); + r = RESUME_GUEST; + } break; /* * This occurs if the guest (kernel or userspace), does something that @@ -831,6 +836,9 @@ static int kvmppc_get_one_reg_hv(struct kvm_vcpu *vcpu, u64 id, long int i; switch (id) { + case KVM_REG_PPC_DEBUG_INST: + *val = get_reg_val(id, KVMPPC_INST_BOOK3S_DEBUG); + break; case KVM_REG_PPC_HIOR: *val = get_reg_val(id, 0); break; diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c index 8eef1e5..27f5234 100644 --- a/arch/powerpc/kvm/book3s_pr.c +++ b/arch/powerpc/kvm/book3s_pr.c @@ -1229,6 +1229,9 @@ static int kvmppc_get_one_reg_pr(struct kvm_vcpu *vcpu, u64 id, int r = 0; switch (id) { + case KVM_REG_PPC_DEBUG_INST: + *val = get_reg_val(id, KVMPPC_INST_BOOK3S_DEBUG); + break; case KVM_REG_PPC_HIOR: *val = get_reg_val(id, to_book3s(vcpu)->hior); break; diff --git a/arch/powerpc/kvm/emulate.c b/arch/powerpc/kvm/emulate.c index da86d9b..d95014e 100644 --- a/arch/powerpc/kvm/emulate.c +++ b/arch/powerpc/kvm/emulate.c @@ -458,6 +458,15 @@ int kvmppc_emulate_instruction(struct kvm_run *run, struct kvm_vcpu *vcpu) kvmppc_set_gpr(vcpu, ra, vcpu->arch.vaddr_accessed); break; + case OP_ZERO: + if((inst & 0x00FFFF00) == KVMPPC_INST_BOOK3S_DEBUG) { + run->exit_reason = KVM_EXIT_DEBUG; + run->debug.arch.address = kvmppc_get_pc(vcpu); + emulated = EMULATE_EXIT_USER; + advance = 0; + } + break; + default: emulated = EMULATE_FAIL; }
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. Changes v2->v3: Changed the debug instructions. Using the all zero opcode in the instruction word as illegal instruction as mentioned in Power ISA instead of ABS Removed reg updated in emulation assist and added a call to kvmppc_emulate_instruction for reg update. 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 <maddy@linux.vnet.ibm.com> --- arch/powerpc/include/asm/kvm_book3s.h | 7 +++++++ arch/powerpc/include/asm/ppc-opcode.h | 5 +++++ arch/powerpc/kvm/book3s.c | 3 ++- arch/powerpc/kvm/book3s_hv.c | 12 ++++++++++-- arch/powerpc/kvm/book3s_pr.c | 3 +++ arch/powerpc/kvm/emulate.c | 9 +++++++++ 6 files changed, 36 insertions(+), 3 deletions(-)