| Message ID | 1463598080-27643-1-git-send-email-thuth@redhat.com |
|---|---|
| State | Accepted |
| Headers | show |
On 18/05/2016 21:01, Thomas Huth wrote: > If kvmppc_handle_exit_pr() calls kvmppc_emulate_instruction() to emulate > one instruction (in the BOOK3S_INTERRUPT_H_EMUL_ASSIST case), it calls > kvmppc_core_queue_program() afterwards if kvmppc_emulate_instruction() > returned EMULATE_FAIL, so the guest gets an program interrupt for the > illegal opcode. > However, the kvmppc_emulate_instruction() also tried to inject a > program exception for this already, so the program interrupt gets > injected twice and the return address in srr0 gets destroyed. > All other callers of kvmppc_emulate_instruction() are also injecting > a program interrupt, and since the callers have the right knowledge > about the srr1 flags that should be used, it is the function > kvmppc_emulate_instruction() that should _not_ inject program > interrupts, so remove the kvmppc_core_queue_program() here. > > This fixes the issue discovered by Laurent Vivier with kvm-unit-tests > where the logs are filled with these messages when the test tries > to execute an illegal instruction: > > Couldn't emulate instruction 0x00000000 (op 0 xop 0) > kvmppc_handle_exit_pr: emulation at 700 failed (00000000) > > Signed-off-by: Thomas Huth <thuth@redhat.com> > --- > arch/powerpc/kvm/emulate.c | 1 - > 1 file changed, 1 deletion(-) > > diff --git a/arch/powerpc/kvm/emulate.c b/arch/powerpc/kvm/emulate.c > index 5cc2e7a..b379146 100644 > --- a/arch/powerpc/kvm/emulate.c > +++ b/arch/powerpc/kvm/emulate.c > @@ -302,7 +302,6 @@ int kvmppc_emulate_instruction(struct kvm_run *run, struct kvm_vcpu *vcpu) > advance = 0; > printk(KERN_ERR "Couldn't emulate instruction 0x%08x " > "(op %d xop %d)\n", inst, get_op(inst), get_xop(inst)); > - kvmppc_core_queue_program(vcpu, 0); > } > } > > I've tested this patch with kvm-unit-tests: it solves the multiple illegal instruction exceptions, but the test fails because SRR1 is not updated correctly. It should contains the bit for "Illegal Instruction" whereas it is 0. [But I think it's what you explain in your last email] Thanks, Laurent -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 05/18/2016 09:01 PM, Thomas Huth wrote: > If kvmppc_handle_exit_pr() calls kvmppc_emulate_instruction() to emulate > one instruction (in the BOOK3S_INTERRUPT_H_EMUL_ASSIST case), it calls > kvmppc_core_queue_program() afterwards if kvmppc_emulate_instruction() > returned EMULATE_FAIL, so the guest gets an program interrupt for the > illegal opcode. > However, the kvmppc_emulate_instruction() also tried to inject a > program exception for this already, so the program interrupt gets > injected twice and the return address in srr0 gets destroyed. > All other callers of kvmppc_emulate_instruction() are also injecting > a program interrupt, and since the callers have the right knowledge > about the srr1 flags that should be used, it is the function > kvmppc_emulate_instruction() that should _not_ inject program > interrupts, so remove the kvmppc_core_queue_program() here. > > This fixes the issue discovered by Laurent Vivier with kvm-unit-tests > where the logs are filled with these messages when the test tries > to execute an illegal instruction: > > Couldn't emulate instruction 0x00000000 (op 0 xop 0) > kvmppc_handle_exit_pr: emulation at 700 failed (00000000) > > Signed-off-by: Thomas Huth <thuth@redhat.com> I'm surprised you're the first one to encounter this :). Reviewed-by: Alexander Graf <agraf@suse.de> Alex -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 05/19/2016 09:58 AM, Laurent Vivier wrote: > > On 18/05/2016 21:01, Thomas Huth wrote: >> If kvmppc_handle_exit_pr() calls kvmppc_emulate_instruction() to emulate >> one instruction (in the BOOK3S_INTERRUPT_H_EMUL_ASSIST case), it calls >> kvmppc_core_queue_program() afterwards if kvmppc_emulate_instruction() >> returned EMULATE_FAIL, so the guest gets an program interrupt for the >> illegal opcode. >> However, the kvmppc_emulate_instruction() also tried to inject a >> program exception for this already, so the program interrupt gets >> injected twice and the return address in srr0 gets destroyed. >> All other callers of kvmppc_emulate_instruction() are also injecting >> a program interrupt, and since the callers have the right knowledge >> about the srr1 flags that should be used, it is the function >> kvmppc_emulate_instruction() that should _not_ inject program >> interrupts, so remove the kvmppc_core_queue_program() here. >> >> This fixes the issue discovered by Laurent Vivier with kvm-unit-tests >> where the logs are filled with these messages when the test tries >> to execute an illegal instruction: >> >> Couldn't emulate instruction 0x00000000 (op 0 xop 0) >> kvmppc_handle_exit_pr: emulation at 700 failed (00000000) >> >> Signed-off-by: Thomas Huth <thuth@redhat.com> >> --- >> arch/powerpc/kvm/emulate.c | 1 - >> 1 file changed, 1 deletion(-) >> >> diff --git a/arch/powerpc/kvm/emulate.c b/arch/powerpc/kvm/emulate.c >> index 5cc2e7a..b379146 100644 >> --- a/arch/powerpc/kvm/emulate.c >> +++ b/arch/powerpc/kvm/emulate.c >> @@ -302,7 +302,6 @@ int kvmppc_emulate_instruction(struct kvm_run *run, struct kvm_vcpu *vcpu) >> advance = 0; >> printk(KERN_ERR "Couldn't emulate instruction 0x%08x " >> "(op %d xop %d)\n", inst, get_op(inst), get_xop(inst)); >> - kvmppc_core_queue_program(vcpu, 0); >> } >> } >> >> > I've tested this patch with kvm-unit-tests: it solves the multiple > illegal instruction exceptions, but the test fails because SRR1 is not > updated correctly. It should contains the bit for "Illegal Instruction" > whereas it is 0. > [But I think it's what you explain in your last email] So if the illegal instruction flag is missing, that's probably because the host CPU didn't pass that in via SRR1. That's probably a subtle difference between EMUL_ASSIST and PROGRAM. Please send a follow-up patch that sets the illegal instruction bit in flags on EMULATE_FAIL as well. Alex -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 19.05.2016 09:58, Laurent Vivier wrote: > > > On 18/05/2016 21:01, Thomas Huth wrote: >> If kvmppc_handle_exit_pr() calls kvmppc_emulate_instruction() to emulate >> one instruction (in the BOOK3S_INTERRUPT_H_EMUL_ASSIST case), it calls >> kvmppc_core_queue_program() afterwards if kvmppc_emulate_instruction() >> returned EMULATE_FAIL, so the guest gets an program interrupt for the >> illegal opcode. >> However, the kvmppc_emulate_instruction() also tried to inject a >> program exception for this already, so the program interrupt gets >> injected twice and the return address in srr0 gets destroyed. >> All other callers of kvmppc_emulate_instruction() are also injecting >> a program interrupt, and since the callers have the right knowledge >> about the srr1 flags that should be used, it is the function >> kvmppc_emulate_instruction() that should _not_ inject program >> interrupts, so remove the kvmppc_core_queue_program() here. >> >> This fixes the issue discovered by Laurent Vivier with kvm-unit-tests >> where the logs are filled with these messages when the test tries >> to execute an illegal instruction: >> >> Couldn't emulate instruction 0x00000000 (op 0 xop 0) >> kvmppc_handle_exit_pr: emulation at 700 failed (00000000) >> >> Signed-off-by: Thomas Huth <thuth@redhat.com> >> --- >> arch/powerpc/kvm/emulate.c | 1 - >> 1 file changed, 1 deletion(-) >> >> diff --git a/arch/powerpc/kvm/emulate.c b/arch/powerpc/kvm/emulate.c >> index 5cc2e7a..b379146 100644 >> --- a/arch/powerpc/kvm/emulate.c >> +++ b/arch/powerpc/kvm/emulate.c >> @@ -302,7 +302,6 @@ int kvmppc_emulate_instruction(struct kvm_run *run, struct kvm_vcpu *vcpu) >> advance = 0; >> printk(KERN_ERR "Couldn't emulate instruction 0x%08x " >> "(op %d xop %d)\n", inst, get_op(inst), get_xop(inst)); >> - kvmppc_core_queue_program(vcpu, 0); >> } >> } >> >> > > I've tested this patch with kvm-unit-tests: it solves the multiple > illegal instruction exceptions, but the test fails because SRR1 is not > updated correctly. It should contains the bit for "Illegal Instruction" > whereas it is 0. > [But I think it's what you explain in your last email] Yes, but that's a separate problem, so I did not include it in this patch here yet. (Also, I'm not sure yet how to exactly fix that other problem with SRR1) Thomas -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 19.05.2016 10:05, Alexander Graf wrote: > On 05/19/2016 09:58 AM, Laurent Vivier wrote: >> >> On 18/05/2016 21:01, Thomas Huth wrote: >>> If kvmppc_handle_exit_pr() calls kvmppc_emulate_instruction() to emulate >>> one instruction (in the BOOK3S_INTERRUPT_H_EMUL_ASSIST case), it calls >>> kvmppc_core_queue_program() afterwards if kvmppc_emulate_instruction() >>> returned EMULATE_FAIL, so the guest gets an program interrupt for the >>> illegal opcode. >>> However, the kvmppc_emulate_instruction() also tried to inject a >>> program exception for this already, so the program interrupt gets >>> injected twice and the return address in srr0 gets destroyed. >>> All other callers of kvmppc_emulate_instruction() are also injecting >>> a program interrupt, and since the callers have the right knowledge >>> about the srr1 flags that should be used, it is the function >>> kvmppc_emulate_instruction() that should _not_ inject program >>> interrupts, so remove the kvmppc_core_queue_program() here. >>> >>> This fixes the issue discovered by Laurent Vivier with kvm-unit-tests >>> where the logs are filled with these messages when the test tries >>> to execute an illegal instruction: >>> >>> Couldn't emulate instruction 0x00000000 (op 0 xop 0) >>> kvmppc_handle_exit_pr: emulation at 700 failed (00000000) >>> >>> Signed-off-by: Thomas Huth <thuth@redhat.com> >>> --- >>> arch/powerpc/kvm/emulate.c | 1 - >>> 1 file changed, 1 deletion(-) >>> >>> diff --git a/arch/powerpc/kvm/emulate.c b/arch/powerpc/kvm/emulate.c >>> index 5cc2e7a..b379146 100644 >>> --- a/arch/powerpc/kvm/emulate.c >>> +++ b/arch/powerpc/kvm/emulate.c >>> @@ -302,7 +302,6 @@ int kvmppc_emulate_instruction(struct kvm_run >>> *run, struct kvm_vcpu *vcpu) >>> advance = 0; >>> printk(KERN_ERR "Couldn't emulate instruction 0x%08x " >>> "(op %d xop %d)\n", inst, get_op(inst), >>> get_xop(inst)); >>> - kvmppc_core_queue_program(vcpu, 0); >>> } >>> } >>> >> I've tested this patch with kvm-unit-tests: it solves the multiple >> illegal instruction exceptions, but the test fails because SRR1 is not >> updated correctly. It should contains the bit for "Illegal Instruction" >> whereas it is 0. >> [But I think it's what you explain in your last email] > > So if the illegal instruction flag is missing, that's probably because > the host CPU didn't pass that in via SRR1. That's probably a subtle > difference between EMUL_ASSIST and PROGRAM. Thanks for that hint! You're right, flags is only 0 if exit_nr is BOOK3S_INTERRUPT_H_EMUL_ASSIST. It seems to contain proper values for BOOK3S_INTERRUPT_PROGRAM, e.g. for privileged-instruction program interrupts. Looking at the PowerISA, this also supports this theory: For emulation assist interrupts, the bits in SRR1 are 0. So the right fix really seems to be to set flags = SRR1_PROGILL in case the function has been called with EMUL_ASSIST. > Please send a follow-up patch that sets the illegal instruction bit in > flags on EMULATE_FAIL as well. I think I'll best send a separate patch, since it is a separate issue. Thomas -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 19/05/2016 10:07, Thomas Huth wrote: > On 19.05.2016 09:58, Laurent Vivier wrote: >> >> >> On 18/05/2016 21:01, Thomas Huth wrote: >>> If kvmppc_handle_exit_pr() calls kvmppc_emulate_instruction() to emulate >>> one instruction (in the BOOK3S_INTERRUPT_H_EMUL_ASSIST case), it calls >>> kvmppc_core_queue_program() afterwards if kvmppc_emulate_instruction() >>> returned EMULATE_FAIL, so the guest gets an program interrupt for the >>> illegal opcode. >>> However, the kvmppc_emulate_instruction() also tried to inject a >>> program exception for this already, so the program interrupt gets >>> injected twice and the return address in srr0 gets destroyed. >>> All other callers of kvmppc_emulate_instruction() are also injecting >>> a program interrupt, and since the callers have the right knowledge >>> about the srr1 flags that should be used, it is the function >>> kvmppc_emulate_instruction() that should _not_ inject program >>> interrupts, so remove the kvmppc_core_queue_program() here. >>> >>> This fixes the issue discovered by Laurent Vivier with kvm-unit-tests >>> where the logs are filled with these messages when the test tries >>> to execute an illegal instruction: >>> >>> Couldn't emulate instruction 0x00000000 (op 0 xop 0) >>> kvmppc_handle_exit_pr: emulation at 700 failed (00000000) >>> >>> Signed-off-by: Thomas Huth <thuth@redhat.com> >>> --- >>> arch/powerpc/kvm/emulate.c | 1 - >>> 1 file changed, 1 deletion(-) >>> >>> diff --git a/arch/powerpc/kvm/emulate.c b/arch/powerpc/kvm/emulate.c >>> index 5cc2e7a..b379146 100644 >>> --- a/arch/powerpc/kvm/emulate.c >>> +++ b/arch/powerpc/kvm/emulate.c >>> @@ -302,7 +302,6 @@ int kvmppc_emulate_instruction(struct kvm_run *run, struct kvm_vcpu *vcpu) >>> advance = 0; >>> printk(KERN_ERR "Couldn't emulate instruction 0x%08x " >>> "(op %d xop %d)\n", inst, get_op(inst), get_xop(inst)); >>> - kvmppc_core_queue_program(vcpu, 0); >>> } >>> } >>> >>> >> >> I've tested this patch with kvm-unit-tests: it solves the multiple >> illegal instruction exceptions, but the test fails because SRR1 is not >> updated correctly. It should contains the bit for "Illegal Instruction" >> whereas it is 0. >> [But I think it's what you explain in your last email] > > Yes, but that's a separate problem, so I did not include it in this > patch here yet. (Also, I'm not sure yet how to exactly fix that other > problem with SRR1) OK, so for this one I can say: Tested-by: Laurent Vivier <lvivier@redhat.com> Laurent -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 19.05.2016 10:04, Alexander Graf wrote: > On 05/18/2016 09:01 PM, Thomas Huth wrote: >> If kvmppc_handle_exit_pr() calls kvmppc_emulate_instruction() to emulate >> one instruction (in the BOOK3S_INTERRUPT_H_EMUL_ASSIST case), it calls >> kvmppc_core_queue_program() afterwards if kvmppc_emulate_instruction() >> returned EMULATE_FAIL, so the guest gets an program interrupt for the >> illegal opcode. >> However, the kvmppc_emulate_instruction() also tried to inject a >> program exception for this already, so the program interrupt gets >> injected twice and the return address in srr0 gets destroyed. >> All other callers of kvmppc_emulate_instruction() are also injecting >> a program interrupt, and since the callers have the right knowledge >> about the srr1 flags that should be used, it is the function >> kvmppc_emulate_instruction() that should _not_ inject program >> interrupts, so remove the kvmppc_core_queue_program() here. >> >> This fixes the issue discovered by Laurent Vivier with kvm-unit-tests >> where the logs are filled with these messages when the test tries >> to execute an illegal instruction: >> >> Couldn't emulate instruction 0x00000000 (op 0 xop 0) >> kvmppc_handle_exit_pr: emulation at 700 failed (00000000) >> >> Signed-off-by: Thomas Huth <thuth@redhat.com> > > I'm surprised you're the first one to encounter this :). > > Reviewed-by: Alexander Graf <agraf@suse.de> *ping* Paul, could you maybe pick up this patch? Thanks, Thomas -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 31.05.2016 12:29, Thomas Huth wrote: > On 19.05.2016 10:04, Alexander Graf wrote: >> On 05/18/2016 09:01 PM, Thomas Huth wrote: >>> If kvmppc_handle_exit_pr() calls kvmppc_emulate_instruction() to emulate >>> one instruction (in the BOOK3S_INTERRUPT_H_EMUL_ASSIST case), it calls >>> kvmppc_core_queue_program() afterwards if kvmppc_emulate_instruction() >>> returned EMULATE_FAIL, so the guest gets an program interrupt for the >>> illegal opcode. >>> However, the kvmppc_emulate_instruction() also tried to inject a >>> program exception for this already, so the program interrupt gets >>> injected twice and the return address in srr0 gets destroyed. >>> All other callers of kvmppc_emulate_instruction() are also injecting >>> a program interrupt, and since the callers have the right knowledge >>> about the srr1 flags that should be used, it is the function >>> kvmppc_emulate_instruction() that should _not_ inject program >>> interrupts, so remove the kvmppc_core_queue_program() here. >>> >>> This fixes the issue discovered by Laurent Vivier with kvm-unit-tests >>> where the logs are filled with these messages when the test tries >>> to execute an illegal instruction: >>> >>> Couldn't emulate instruction 0x00000000 (op 0 xop 0) >>> kvmppc_handle_exit_pr: emulation at 700 failed (00000000) >>> >>> Signed-off-by: Thomas Huth <thuth@redhat.com> >> >> I'm surprised you're the first one to encounter this :). >> >> Reviewed-by: Alexander Graf <agraf@suse.de> > > *ping* > > Paul, could you maybe pick up this patch? ping^2 Thomas -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Wed, May 18, 2016 at 09:01:20PM +0200, Thomas Huth wrote: > If kvmppc_handle_exit_pr() calls kvmppc_emulate_instruction() to emulate > one instruction (in the BOOK3S_INTERRUPT_H_EMUL_ASSIST case), it calls > kvmppc_core_queue_program() afterwards if kvmppc_emulate_instruction() > returned EMULATE_FAIL, so the guest gets an program interrupt for the > illegal opcode. > However, the kvmppc_emulate_instruction() also tried to inject a > program exception for this already, so the program interrupt gets > injected twice and the return address in srr0 gets destroyed. > All other callers of kvmppc_emulate_instruction() are also injecting > a program interrupt, and since the callers have the right knowledge > about the srr1 flags that should be used, it is the function > kvmppc_emulate_instruction() that should _not_ inject program > interrupts, so remove the kvmppc_core_queue_program() here. > > This fixes the issue discovered by Laurent Vivier with kvm-unit-tests > where the logs are filled with these messages when the test tries > to execute an illegal instruction: > > Couldn't emulate instruction 0x00000000 (op 0 xop 0) > kvmppc_handle_exit_pr: emulation at 700 failed (00000000) > > Signed-off-by: Thomas Huth <thuth@redhat.com> Thanks, applied to my kvm-ppc-next branch (with adjusted subject). Paul. -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/arch/powerpc/kvm/emulate.c b/arch/powerpc/kvm/emulate.c index 5cc2e7a..b379146 100644 --- a/arch/powerpc/kvm/emulate.c +++ b/arch/powerpc/kvm/emulate.c @@ -302,7 +302,6 @@ int kvmppc_emulate_instruction(struct kvm_run *run, struct kvm_vcpu *vcpu) advance = 0; printk(KERN_ERR "Couldn't emulate instruction 0x%08x " "(op %d xop %d)\n", inst, get_op(inst), get_xop(inst)); - kvmppc_core_queue_program(vcpu, 0); } }
If kvmppc_handle_exit_pr() calls kvmppc_emulate_instruction() to emulate one instruction (in the BOOK3S_INTERRUPT_H_EMUL_ASSIST case), it calls kvmppc_core_queue_program() afterwards if kvmppc_emulate_instruction() returned EMULATE_FAIL, so the guest gets an program interrupt for the illegal opcode. However, the kvmppc_emulate_instruction() also tried to inject a program exception for this already, so the program interrupt gets injected twice and the return address in srr0 gets destroyed. All other callers of kvmppc_emulate_instruction() are also injecting a program interrupt, and since the callers have the right knowledge about the srr1 flags that should be used, it is the function kvmppc_emulate_instruction() that should _not_ inject program interrupts, so remove the kvmppc_core_queue_program() here. This fixes the issue discovered by Laurent Vivier with kvm-unit-tests where the logs are filled with these messages when the test tries to execute an illegal instruction: Couldn't emulate instruction 0x00000000 (op 0 xop 0) kvmppc_handle_exit_pr: emulation at 700 failed (00000000) Signed-off-by: Thomas Huth <thuth@redhat.com> --- arch/powerpc/kvm/emulate.c | 1 - 1 file changed, 1 deletion(-)