Re: [PATCH v2] KVM: PPC: Exit guest upon fatal machine check exception
On Thursday 17 December 2015 08:02 AM, David Gibson wrote: > On Wed, Dec 16, 2015 at 11:26:12AM +0530, Aravinda Prasad wrote: >> This patch modifies KVM to cause a guest exit with >> KVM_EXIT_NMI instead of immediately delivering a 0x200 >> interrupt to guest upon machine check exception in >> guest address. Exiting the guest enables QEMU to build >> error log and deliver machine check exception to guest >> OS (either via guest OS registered machine check >> handler or via 0x200 guest OS interrupt vector). >> >> This approach simplifies the delivering of machine >> check exception to guest OS compared to the earlier approach >> of KVM directly invoking 0x200 guest interrupt vector. >> In the earlier approach QEMU patched the 0x200 interrupt >> vector during boot. The patched code at 0x200 issued a >> private hcall to pass the control to QEMU to build the >> error log. >> >> This design/approach is based on the feedback for the >> QEMU patches to handle machine check exception. Details >> of earlier approach of handling machine check exception >> in QEMU and related discussions can be found at: >> >> https://lists.nongnu.org/archive/html/qemu-devel/2014-11/msg00813.html >> >> This patch also introduces a new KVM capability to >> control how KVM behaves on machine check exception. >> Without this capability, KVM redirects machine check >> exceptions to guest's 0x200 vector if the address in >> error belongs to guest. With this capability KVM >> causes a guest exit with NMI exit reason. >> >> This is required to avoid problems if a new kernel/KVM >> is used with an old QEMU for guests that don't issue >> "ibm,nmi-register". As old QEMU does not understand the >> NMI exit type, it treats it as a fatal error. However, >> the guest could have handled the machine check error >> if the exception was delivered to guest's 0x200 interrupt >> vector instead of NMI exit in case of old QEMU. >> >> Change Log v2: >> - Added KVM capability >> >> Signed-off-by: Aravinda Prasad>> --- >> arch/powerpc/include/asm/kvm_host.h |1 + >> arch/powerpc/kernel/asm-offsets.c |1 + >> arch/powerpc/kvm/book3s_hv.c| 12 +++--- >> arch/powerpc/kvm/book3s_hv_rmhandlers.S | 37 >> +++ >> arch/powerpc/kvm/powerpc.c |7 ++ >> include/uapi/linux/kvm.h|1 + >> 6 files changed, 31 insertions(+), 28 deletions(-) >> >> diff --git a/arch/powerpc/include/asm/kvm_host.h >> b/arch/powerpc/include/asm/kvm_host.h >> index 827a38d..8a652ba 100644 >> --- a/arch/powerpc/include/asm/kvm_host.h >> +++ b/arch/powerpc/include/asm/kvm_host.h >> @@ -243,6 +243,7 @@ struct kvm_arch { >> int hpt_cma_alloc; >> struct dentry *debugfs_dir; >> struct dentry *htab_dentry; >> +u8 fwnmi_enabled; >> #endif /* CONFIG_KVM_BOOK3S_HV_POSSIBLE */ >> #ifdef CONFIG_KVM_BOOK3S_PR_POSSIBLE >> struct mutex hpt_mutex; >> diff --git a/arch/powerpc/kernel/asm-offsets.c >> b/arch/powerpc/kernel/asm-offsets.c >> index 221d584..6a4e81a 100644 >> --- a/arch/powerpc/kernel/asm-offsets.c >> +++ b/arch/powerpc/kernel/asm-offsets.c >> @@ -506,6 +506,7 @@ int main(void) >> DEFINE(KVM_ENABLED_HCALLS, offsetof(struct kvm, arch.enabled_hcalls)); >> DEFINE(KVM_LPCR, offsetof(struct kvm, arch.lpcr)); >> DEFINE(KVM_VRMA_SLB_V, offsetof(struct kvm, arch.vrma_slb_v)); >> +DEFINE(KVM_FWNMI, offsetof(struct kvm, arch.fwnmi_enabled)); >> DEFINE(VCPU_DSISR, offsetof(struct kvm_vcpu, arch.shregs.dsisr)); >> DEFINE(VCPU_DAR, offsetof(struct kvm_vcpu, arch.shregs.dar)); >> DEFINE(VCPU_VPA, offsetof(struct kvm_vcpu, arch.vpa.pinned_addr)); >> diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c >> index 2280497..1b1dff0 100644 >> --- a/arch/powerpc/kvm/book3s_hv.c >> +++ b/arch/powerpc/kvm/book3s_hv.c >> @@ -859,15 +859,9 @@ static int kvmppc_handle_exit_hv(struct kvm_run *run, >> struct kvm_vcpu *vcpu, >> r = RESUME_GUEST; >> break; >> case BOOK3S_INTERRUPT_MACHINE_CHECK: >> -/* >> - * Deliver a machine check interrupt to the guest. >> - * We have to do this, even if the host has handled the >> - * machine check, because machine checks use SRR0/1 and >> - * the interrupt might have trashed guest state in them. >> - */ >> -kvmppc_book3s_queue_irqprio(vcpu, >> -BOOK3S_INTERRUPT_MACHINE_CHECK); >> -r = RESUME_GUEST; >> +/* Exit to guest with KVM_EXIT_NMI as exit reason */ >> +run->exit_reason = KVM_EXIT_NMI; >> +r = RESUME_HOST; >> break; >> case BOOK3S_INTERRUPT_PROGRAM: >> { >> diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S >> b/arch/powerpc/kvm/book3s_hv_rmhandlers.S >> index b98889e..f43c124 100644 >> --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S >> +++
Re: [PATCH v2] KVM: PPC: Exit guest upon fatal machine check exception
On Thursday 17 December 2015 08:02 AM, David Gibson wrote: > On Wed, Dec 16, 2015 at 11:26:12AM +0530, Aravinda Prasad wrote: >> This patch modifies KVM to cause a guest exit with >> KVM_EXIT_NMI instead of immediately delivering a 0x200 >> interrupt to guest upon machine check exception in >> guest address. Exiting the guest enables QEMU to build >> error log and deliver machine check exception to guest >> OS (either via guest OS registered machine check >> handler or via 0x200 guest OS interrupt vector). >> >> This approach simplifies the delivering of machine >> check exception to guest OS compared to the earlier approach >> of KVM directly invoking 0x200 guest interrupt vector. >> In the earlier approach QEMU patched the 0x200 interrupt >> vector during boot. The patched code at 0x200 issued a >> private hcall to pass the control to QEMU to build the >> error log. >> >> This design/approach is based on the feedback for the >> QEMU patches to handle machine check exception. Details >> of earlier approach of handling machine check exception >> in QEMU and related discussions can be found at: >> >> https://lists.nongnu.org/archive/html/qemu-devel/2014-11/msg00813.html >> >> This patch also introduces a new KVM capability to >> control how KVM behaves on machine check exception. >> Without this capability, KVM redirects machine check >> exceptions to guest's 0x200 vector if the address in >> error belongs to guest. With this capability KVM >> causes a guest exit with NMI exit reason. >> >> This is required to avoid problems if a new kernel/KVM >> is used with an old QEMU for guests that don't issue >> "ibm,nmi-register". As old QEMU does not understand the >> NMI exit type, it treats it as a fatal error. However, >> the guest could have handled the machine check error >> if the exception was delivered to guest's 0x200 interrupt >> vector instead of NMI exit in case of old QEMU. >> >> Change Log v2: >> - Added KVM capability >> >> Signed-off-by: Aravinda Prasad>> --- >> arch/powerpc/include/asm/kvm_host.h |1 + >> arch/powerpc/kernel/asm-offsets.c |1 + >> arch/powerpc/kvm/book3s_hv.c| 12 +++--- >> arch/powerpc/kvm/book3s_hv_rmhandlers.S | 37 >> +++ >> arch/powerpc/kvm/powerpc.c |7 ++ >> include/uapi/linux/kvm.h|1 + >> 6 files changed, 31 insertions(+), 28 deletions(-) >> >> diff --git a/arch/powerpc/include/asm/kvm_host.h >> b/arch/powerpc/include/asm/kvm_host.h >> index 827a38d..8a652ba 100644 >> --- a/arch/powerpc/include/asm/kvm_host.h >> +++ b/arch/powerpc/include/asm/kvm_host.h >> @@ -243,6 +243,7 @@ struct kvm_arch { >> int hpt_cma_alloc; >> struct dentry *debugfs_dir; >> struct dentry *htab_dentry; >> +u8 fwnmi_enabled; >> #endif /* CONFIG_KVM_BOOK3S_HV_POSSIBLE */ >> #ifdef CONFIG_KVM_BOOK3S_PR_POSSIBLE >> struct mutex hpt_mutex; >> diff --git a/arch/powerpc/kernel/asm-offsets.c >> b/arch/powerpc/kernel/asm-offsets.c >> index 221d584..6a4e81a 100644 >> --- a/arch/powerpc/kernel/asm-offsets.c >> +++ b/arch/powerpc/kernel/asm-offsets.c >> @@ -506,6 +506,7 @@ int main(void) >> DEFINE(KVM_ENABLED_HCALLS, offsetof(struct kvm, arch.enabled_hcalls)); >> DEFINE(KVM_LPCR, offsetof(struct kvm, arch.lpcr)); >> DEFINE(KVM_VRMA_SLB_V, offsetof(struct kvm, arch.vrma_slb_v)); >> +DEFINE(KVM_FWNMI, offsetof(struct kvm, arch.fwnmi_enabled)); >> DEFINE(VCPU_DSISR, offsetof(struct kvm_vcpu, arch.shregs.dsisr)); >> DEFINE(VCPU_DAR, offsetof(struct kvm_vcpu, arch.shregs.dar)); >> DEFINE(VCPU_VPA, offsetof(struct kvm_vcpu, arch.vpa.pinned_addr)); >> diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c >> index 2280497..1b1dff0 100644 >> --- a/arch/powerpc/kvm/book3s_hv.c >> +++ b/arch/powerpc/kvm/book3s_hv.c >> @@ -859,15 +859,9 @@ static int kvmppc_handle_exit_hv(struct kvm_run *run, >> struct kvm_vcpu *vcpu, >> r = RESUME_GUEST; >> break; >> case BOOK3S_INTERRUPT_MACHINE_CHECK: >> -/* >> - * Deliver a machine check interrupt to the guest. >> - * We have to do this, even if the host has handled the >> - * machine check, because machine checks use SRR0/1 and >> - * the interrupt might have trashed guest state in them. >> - */ >> -kvmppc_book3s_queue_irqprio(vcpu, >> -BOOK3S_INTERRUPT_MACHINE_CHECK); >> -r = RESUME_GUEST; >> +/* Exit to guest with KVM_EXIT_NMI as exit reason */ >> +run->exit_reason = KVM_EXIT_NMI; >> +r = RESUME_HOST; >> break; >> case BOOK3S_INTERRUPT_PROGRAM: >> { >> diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S >> b/arch/powerpc/kvm/book3s_hv_rmhandlers.S >> index b98889e..f43c124 100644 >> --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S >> +++
Re: [PATCH v2] KVM: PPC: Exit guest upon fatal machine check exception
On Wed, Dec 16, 2015 at 11:26:12AM +0530, Aravinda Prasad wrote: > This patch modifies KVM to cause a guest exit with > KVM_EXIT_NMI instead of immediately delivering a 0x200 > interrupt to guest upon machine check exception in > guest address. Exiting the guest enables QEMU to build > error log and deliver machine check exception to guest > OS (either via guest OS registered machine check > handler or via 0x200 guest OS interrupt vector). > > This approach simplifies the delivering of machine > check exception to guest OS compared to the earlier approach > of KVM directly invoking 0x200 guest interrupt vector. > In the earlier approach QEMU patched the 0x200 interrupt > vector during boot. The patched code at 0x200 issued a > private hcall to pass the control to QEMU to build the > error log. > > This design/approach is based on the feedback for the > QEMU patches to handle machine check exception. Details > of earlier approach of handling machine check exception > in QEMU and related discussions can be found at: > > https://lists.nongnu.org/archive/html/qemu-devel/2014-11/msg00813.html > > This patch also introduces a new KVM capability to > control how KVM behaves on machine check exception. > Without this capability, KVM redirects machine check > exceptions to guest's 0x200 vector if the address in > error belongs to guest. With this capability KVM > causes a guest exit with NMI exit reason. > > This is required to avoid problems if a new kernel/KVM > is used with an old QEMU for guests that don't issue > "ibm,nmi-register". As old QEMU does not understand the > NMI exit type, it treats it as a fatal error. However, > the guest could have handled the machine check error > if the exception was delivered to guest's 0x200 interrupt > vector instead of NMI exit in case of old QEMU. > > Change Log v2: > - Added KVM capability > > Signed-off-by: Aravinda Prasad> --- > arch/powerpc/include/asm/kvm_host.h |1 + > arch/powerpc/kernel/asm-offsets.c |1 + > arch/powerpc/kvm/book3s_hv.c| 12 +++--- > arch/powerpc/kvm/book3s_hv_rmhandlers.S | 37 > +++ > arch/powerpc/kvm/powerpc.c |7 ++ > include/uapi/linux/kvm.h|1 + > 6 files changed, 31 insertions(+), 28 deletions(-) > > diff --git a/arch/powerpc/include/asm/kvm_host.h > b/arch/powerpc/include/asm/kvm_host.h > index 827a38d..8a652ba 100644 > --- a/arch/powerpc/include/asm/kvm_host.h > +++ b/arch/powerpc/include/asm/kvm_host.h > @@ -243,6 +243,7 @@ struct kvm_arch { > int hpt_cma_alloc; > struct dentry *debugfs_dir; > struct dentry *htab_dentry; > + u8 fwnmi_enabled; > #endif /* CONFIG_KVM_BOOK3S_HV_POSSIBLE */ > #ifdef CONFIG_KVM_BOOK3S_PR_POSSIBLE > struct mutex hpt_mutex; > diff --git a/arch/powerpc/kernel/asm-offsets.c > b/arch/powerpc/kernel/asm-offsets.c > index 221d584..6a4e81a 100644 > --- a/arch/powerpc/kernel/asm-offsets.c > +++ b/arch/powerpc/kernel/asm-offsets.c > @@ -506,6 +506,7 @@ int main(void) > DEFINE(KVM_ENABLED_HCALLS, offsetof(struct kvm, arch.enabled_hcalls)); > DEFINE(KVM_LPCR, offsetof(struct kvm, arch.lpcr)); > DEFINE(KVM_VRMA_SLB_V, offsetof(struct kvm, arch.vrma_slb_v)); > + DEFINE(KVM_FWNMI, offsetof(struct kvm, arch.fwnmi_enabled)); > DEFINE(VCPU_DSISR, offsetof(struct kvm_vcpu, arch.shregs.dsisr)); > DEFINE(VCPU_DAR, offsetof(struct kvm_vcpu, arch.shregs.dar)); > DEFINE(VCPU_VPA, offsetof(struct kvm_vcpu, arch.vpa.pinned_addr)); > diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c > index 2280497..1b1dff0 100644 > --- a/arch/powerpc/kvm/book3s_hv.c > +++ b/arch/powerpc/kvm/book3s_hv.c > @@ -859,15 +859,9 @@ static int kvmppc_handle_exit_hv(struct kvm_run *run, > struct kvm_vcpu *vcpu, > r = RESUME_GUEST; > break; > case BOOK3S_INTERRUPT_MACHINE_CHECK: > - /* > - * Deliver a machine check interrupt to the guest. > - * We have to do this, even if the host has handled the > - * machine check, because machine checks use SRR0/1 and > - * the interrupt might have trashed guest state in them. > - */ > - kvmppc_book3s_queue_irqprio(vcpu, > - BOOK3S_INTERRUPT_MACHINE_CHECK); > - r = RESUME_GUEST; > + /* Exit to guest with KVM_EXIT_NMI as exit reason */ > + run->exit_reason = KVM_EXIT_NMI; > + r = RESUME_HOST; > break; > case BOOK3S_INTERRUPT_PROGRAM: > { > diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S > b/arch/powerpc/kvm/book3s_hv_rmhandlers.S > index b98889e..f43c124 100644 > --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S > +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S > @@ -147,7 +147,6 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S) > addir1, r1, 112
Re: [PATCH v2] KVM: PPC: Exit guest upon fatal machine check exception
On Wed, Dec 16, 2015 at 11:26:12AM +0530, Aravinda Prasad wrote: > This patch modifies KVM to cause a guest exit with > KVM_EXIT_NMI instead of immediately delivering a 0x200 > interrupt to guest upon machine check exception in > guest address. Exiting the guest enables QEMU to build > error log and deliver machine check exception to guest > OS (either via guest OS registered machine check > handler or via 0x200 guest OS interrupt vector). > > This approach simplifies the delivering of machine > check exception to guest OS compared to the earlier approach > of KVM directly invoking 0x200 guest interrupt vector. > In the earlier approach QEMU patched the 0x200 interrupt > vector during boot. The patched code at 0x200 issued a > private hcall to pass the control to QEMU to build the > error log. > > This design/approach is based on the feedback for the > QEMU patches to handle machine check exception. Details > of earlier approach of handling machine check exception > in QEMU and related discussions can be found at: > > https://lists.nongnu.org/archive/html/qemu-devel/2014-11/msg00813.html > > This patch also introduces a new KVM capability to > control how KVM behaves on machine check exception. > Without this capability, KVM redirects machine check > exceptions to guest's 0x200 vector if the address in > error belongs to guest. With this capability KVM > causes a guest exit with NMI exit reason. > > This is required to avoid problems if a new kernel/KVM > is used with an old QEMU for guests that don't issue > "ibm,nmi-register". As old QEMU does not understand the > NMI exit type, it treats it as a fatal error. However, > the guest could have handled the machine check error > if the exception was delivered to guest's 0x200 interrupt > vector instead of NMI exit in case of old QEMU. > > Change Log v2: > - Added KVM capability > > Signed-off-by: Aravinda Prasad> --- > arch/powerpc/include/asm/kvm_host.h |1 + > arch/powerpc/kernel/asm-offsets.c |1 + > arch/powerpc/kvm/book3s_hv.c| 12 +++--- > arch/powerpc/kvm/book3s_hv_rmhandlers.S | 37 > +++ > arch/powerpc/kvm/powerpc.c |7 ++ > include/uapi/linux/kvm.h|1 + > 6 files changed, 31 insertions(+), 28 deletions(-) > > diff --git a/arch/powerpc/include/asm/kvm_host.h > b/arch/powerpc/include/asm/kvm_host.h > index 827a38d..8a652ba 100644 > --- a/arch/powerpc/include/asm/kvm_host.h > +++ b/arch/powerpc/include/asm/kvm_host.h > @@ -243,6 +243,7 @@ struct kvm_arch { > int hpt_cma_alloc; > struct dentry *debugfs_dir; > struct dentry *htab_dentry; > + u8 fwnmi_enabled; > #endif /* CONFIG_KVM_BOOK3S_HV_POSSIBLE */ > #ifdef CONFIG_KVM_BOOK3S_PR_POSSIBLE > struct mutex hpt_mutex; > diff --git a/arch/powerpc/kernel/asm-offsets.c > b/arch/powerpc/kernel/asm-offsets.c > index 221d584..6a4e81a 100644 > --- a/arch/powerpc/kernel/asm-offsets.c > +++ b/arch/powerpc/kernel/asm-offsets.c > @@ -506,6 +506,7 @@ int main(void) > DEFINE(KVM_ENABLED_HCALLS, offsetof(struct kvm, arch.enabled_hcalls)); > DEFINE(KVM_LPCR, offsetof(struct kvm, arch.lpcr)); > DEFINE(KVM_VRMA_SLB_V, offsetof(struct kvm, arch.vrma_slb_v)); > + DEFINE(KVM_FWNMI, offsetof(struct kvm, arch.fwnmi_enabled)); > DEFINE(VCPU_DSISR, offsetof(struct kvm_vcpu, arch.shregs.dsisr)); > DEFINE(VCPU_DAR, offsetof(struct kvm_vcpu, arch.shregs.dar)); > DEFINE(VCPU_VPA, offsetof(struct kvm_vcpu, arch.vpa.pinned_addr)); > diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c > index 2280497..1b1dff0 100644 > --- a/arch/powerpc/kvm/book3s_hv.c > +++ b/arch/powerpc/kvm/book3s_hv.c > @@ -859,15 +859,9 @@ static int kvmppc_handle_exit_hv(struct kvm_run *run, > struct kvm_vcpu *vcpu, > r = RESUME_GUEST; > break; > case BOOK3S_INTERRUPT_MACHINE_CHECK: > - /* > - * Deliver a machine check interrupt to the guest. > - * We have to do this, even if the host has handled the > - * machine check, because machine checks use SRR0/1 and > - * the interrupt might have trashed guest state in them. > - */ > - kvmppc_book3s_queue_irqprio(vcpu, > - BOOK3S_INTERRUPT_MACHINE_CHECK); > - r = RESUME_GUEST; > + /* Exit to guest with KVM_EXIT_NMI as exit reason */ > + run->exit_reason = KVM_EXIT_NMI; > + r = RESUME_HOST; > break; > case BOOK3S_INTERRUPT_PROGRAM: > { > diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S > b/arch/powerpc/kvm/book3s_hv_rmhandlers.S > index b98889e..f43c124 100644 > --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S > +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S > @@ -147,7 +147,6 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S) > addir1, r1, 112
Re: [PATCH v2] KVM: PPC: Exit guest upon fatal machine check exception
On Wednesday 16 December 2015 03:10 PM, Thomas Huth wrote: > On 16/12/15 06:56, Aravinda Prasad wrote: >> This patch modifies KVM to cause a guest exit with >> KVM_EXIT_NMI instead of immediately delivering a 0x200 >> interrupt to guest upon machine check exception in >> guest address. Exiting the guest enables QEMU to build >> error log and deliver machine check exception to guest >> OS (either via guest OS registered machine check >> handler or via 0x200 guest OS interrupt vector). >> >> This approach simplifies the delivering of machine >> check exception to guest OS compared to the earlier approach >> of KVM directly invoking 0x200 guest interrupt vector. >> In the earlier approach QEMU patched the 0x200 interrupt >> vector during boot. The patched code at 0x200 issued a >> private hcall to pass the control to QEMU to build the >> error log. >> >> This design/approach is based on the feedback for the >> QEMU patches to handle machine check exception. Details >> of earlier approach of handling machine check exception >> in QEMU and related discussions can be found at: >> >> https://lists.nongnu.org/archive/html/qemu-devel/2014-11/msg00813.html >> >> This patch also introduces a new KVM capability to >> control how KVM behaves on machine check exception. >> Without this capability, KVM redirects machine check >> exceptions to guest's 0x200 vector if the address in >> error belongs to guest. With this capability KVM >> causes a guest exit with NMI exit reason. >> >> This is required to avoid problems if a new kernel/KVM >> is used with an old QEMU for guests that don't issue >> "ibm,nmi-register". As old QEMU does not understand the >> NMI exit type, it treats it as a fatal error. However, >> the guest could have handled the machine check error >> if the exception was delivered to guest's 0x200 interrupt >> vector instead of NMI exit in case of old QEMU. >> >> Change Log v2: >> - Added KVM capability >> >> Signed-off-by: Aravinda Prasad>> --- >> arch/powerpc/include/asm/kvm_host.h |1 + >> arch/powerpc/kernel/asm-offsets.c |1 + >> arch/powerpc/kvm/book3s_hv.c| 12 +++--- >> arch/powerpc/kvm/book3s_hv_rmhandlers.S | 37 >> +++ >> arch/powerpc/kvm/powerpc.c |7 ++ >> include/uapi/linux/kvm.h|1 + >> 6 files changed, 31 insertions(+), 28 deletions(-) >> >> diff --git a/arch/powerpc/include/asm/kvm_host.h >> b/arch/powerpc/include/asm/kvm_host.h >> index 827a38d..8a652ba 100644 >> --- a/arch/powerpc/include/asm/kvm_host.h >> +++ b/arch/powerpc/include/asm/kvm_host.h >> @@ -243,6 +243,7 @@ struct kvm_arch { >> int hpt_cma_alloc; >> struct dentry *debugfs_dir; >> struct dentry *htab_dentry; >> +u8 fwnmi_enabled; > > Here you declare the variable as 8-bits ... > >> #endif /* CONFIG_KVM_BOOK3S_HV_POSSIBLE */ >> #ifdef CONFIG_KVM_BOOK3S_PR_POSSIBLE >> struct mutex hpt_mutex; >> diff --git a/arch/powerpc/kernel/asm-offsets.c >> b/arch/powerpc/kernel/asm-offsets.c >> index 221d584..6a4e81a 100644 >> --- a/arch/powerpc/kernel/asm-offsets.c >> +++ b/arch/powerpc/kernel/asm-offsets.c >> @@ -506,6 +506,7 @@ int main(void) >> DEFINE(KVM_ENABLED_HCALLS, offsetof(struct kvm, arch.enabled_hcalls)); >> DEFINE(KVM_LPCR, offsetof(struct kvm, arch.lpcr)); >> DEFINE(KVM_VRMA_SLB_V, offsetof(struct kvm, arch.vrma_slb_v)); >> +DEFINE(KVM_FWNMI, offsetof(struct kvm, arch.fwnmi_enabled)); > > ... then define an asm-offset for it ... > >> DEFINE(VCPU_DSISR, offsetof(struct kvm_vcpu, arch.shregs.dsisr)); >> DEFINE(VCPU_DAR, offsetof(struct kvm_vcpu, arch.shregs.dar)); >> DEFINE(VCPU_VPA, offsetof(struct kvm_vcpu, arch.vpa.pinned_addr)); >> diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S >> b/arch/powerpc/kvm/book3s_hv_rmhandlers.S >> index b98889e..f43c124 100644 >> --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S >> +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S > [...] >> @@ -2381,24 +2377,27 @@ machine_check_realmode: >> ld r9, HSTATE_KVM_VCPU(r13) >> li r12, BOOK3S_INTERRUPT_MACHINE_CHECK >> /* >> - * Deliver unhandled/fatal (e.g. UE) MCE errors to guest through >> - * machine check interrupt (set HSRR0 to 0x200). And for handled >> - * errors (no-fatal), just go back to guest execution with current >> - * HSRR0 instead of exiting guest. This new approach will inject >> - * machine check to guest for fatal error causing guest to crash. >> - * >> - * The old code used to return to host for unhandled errors which >> - * was causing guest to hang with soft lockups inside guest and >> - * makes it difficult to recover guest instance. >> + * Deliver unhandled/fatal (e.g. UE) MCE errors to guest >> + * by exiting the guest with KVM_EXIT_NMI exit reason (exit >> + * reason set later based on trap). For handled errors >> + * (no-fatal), go back to guest
Re: [PATCH v2] KVM: PPC: Exit guest upon fatal machine check exception
On Wednesday 16 December 2015 03:10 PM, Thomas Huth wrote: > On 16/12/15 06:56, Aravinda Prasad wrote: >> This patch modifies KVM to cause a guest exit with >> KVM_EXIT_NMI instead of immediately delivering a 0x200 >> interrupt to guest upon machine check exception in >> guest address. Exiting the guest enables QEMU to build >> error log and deliver machine check exception to guest >> OS (either via guest OS registered machine check >> handler or via 0x200 guest OS interrupt vector). >> >> This approach simplifies the delivering of machine >> check exception to guest OS compared to the earlier approach >> of KVM directly invoking 0x200 guest interrupt vector. >> In the earlier approach QEMU patched the 0x200 interrupt >> vector during boot. The patched code at 0x200 issued a >> private hcall to pass the control to QEMU to build the >> error log. >> >> This design/approach is based on the feedback for the >> QEMU patches to handle machine check exception. Details >> of earlier approach of handling machine check exception >> in QEMU and related discussions can be found at: >> >> https://lists.nongnu.org/archive/html/qemu-devel/2014-11/msg00813.html >> >> This patch also introduces a new KVM capability to >> control how KVM behaves on machine check exception. >> Without this capability, KVM redirects machine check >> exceptions to guest's 0x200 vector if the address in >> error belongs to guest. With this capability KVM >> causes a guest exit with NMI exit reason. >> >> This is required to avoid problems if a new kernel/KVM >> is used with an old QEMU for guests that don't issue >> "ibm,nmi-register". As old QEMU does not understand the >> NMI exit type, it treats it as a fatal error. However, >> the guest could have handled the machine check error >> if the exception was delivered to guest's 0x200 interrupt >> vector instead of NMI exit in case of old QEMU. >> >> Change Log v2: >> - Added KVM capability >> >> Signed-off-by: Aravinda Prasad>> --- >> arch/powerpc/include/asm/kvm_host.h |1 + >> arch/powerpc/kernel/asm-offsets.c |1 + >> arch/powerpc/kvm/book3s_hv.c| 12 +++--- >> arch/powerpc/kvm/book3s_hv_rmhandlers.S | 37 >> +++ >> arch/powerpc/kvm/powerpc.c |7 ++ >> include/uapi/linux/kvm.h|1 + >> 6 files changed, 31 insertions(+), 28 deletions(-) >> >> diff --git a/arch/powerpc/include/asm/kvm_host.h >> b/arch/powerpc/include/asm/kvm_host.h >> index 827a38d..8a652ba 100644 >> --- a/arch/powerpc/include/asm/kvm_host.h >> +++ b/arch/powerpc/include/asm/kvm_host.h >> @@ -243,6 +243,7 @@ struct kvm_arch { >> int hpt_cma_alloc; >> struct dentry *debugfs_dir; >> struct dentry *htab_dentry; >> +u8 fwnmi_enabled; > > Here you declare the variable as 8-bits ... > >> #endif /* CONFIG_KVM_BOOK3S_HV_POSSIBLE */ >> #ifdef CONFIG_KVM_BOOK3S_PR_POSSIBLE >> struct mutex hpt_mutex; >> diff --git a/arch/powerpc/kernel/asm-offsets.c >> b/arch/powerpc/kernel/asm-offsets.c >> index 221d584..6a4e81a 100644 >> --- a/arch/powerpc/kernel/asm-offsets.c >> +++ b/arch/powerpc/kernel/asm-offsets.c >> @@ -506,6 +506,7 @@ int main(void) >> DEFINE(KVM_ENABLED_HCALLS, offsetof(struct kvm, arch.enabled_hcalls)); >> DEFINE(KVM_LPCR, offsetof(struct kvm, arch.lpcr)); >> DEFINE(KVM_VRMA_SLB_V, offsetof(struct kvm, arch.vrma_slb_v)); >> +DEFINE(KVM_FWNMI, offsetof(struct kvm, arch.fwnmi_enabled)); > > ... then define an asm-offset for it ... > >> DEFINE(VCPU_DSISR, offsetof(struct kvm_vcpu, arch.shregs.dsisr)); >> DEFINE(VCPU_DAR, offsetof(struct kvm_vcpu, arch.shregs.dar)); >> DEFINE(VCPU_VPA, offsetof(struct kvm_vcpu, arch.vpa.pinned_addr)); >> diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S >> b/arch/powerpc/kvm/book3s_hv_rmhandlers.S >> index b98889e..f43c124 100644 >> --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S >> +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S > [...] >> @@ -2381,24 +2377,27 @@ machine_check_realmode: >> ld r9, HSTATE_KVM_VCPU(r13) >> li r12, BOOK3S_INTERRUPT_MACHINE_CHECK >> /* >> - * Deliver unhandled/fatal (e.g. UE) MCE errors to guest through >> - * machine check interrupt (set HSRR0 to 0x200). And for handled >> - * errors (no-fatal), just go back to guest execution with current >> - * HSRR0 instead of exiting guest. This new approach will inject >> - * machine check to guest for fatal error causing guest to crash. >> - * >> - * The old code used to return to host for unhandled errors which >> - * was causing guest to hang with soft lockups inside guest and >> - * makes it difficult to recover guest instance. >> + * Deliver unhandled/fatal (e.g. UE) MCE errors to guest >> + * by exiting the guest with KVM_EXIT_NMI exit reason (exit >> + * reason set later based on trap). For handled errors >> + * (no-fatal), go back to guest
Re: [PATCH v2] KVM: PPC: Exit guest upon fatal machine check exception
On 16/12/15 06:56, Aravinda Prasad wrote: > This patch modifies KVM to cause a guest exit with > KVM_EXIT_NMI instead of immediately delivering a 0x200 > interrupt to guest upon machine check exception in > guest address. Exiting the guest enables QEMU to build > error log and deliver machine check exception to guest > OS (either via guest OS registered machine check > handler or via 0x200 guest OS interrupt vector). > > This approach simplifies the delivering of machine > check exception to guest OS compared to the earlier approach > of KVM directly invoking 0x200 guest interrupt vector. > In the earlier approach QEMU patched the 0x200 interrupt > vector during boot. The patched code at 0x200 issued a > private hcall to pass the control to QEMU to build the > error log. > > This design/approach is based on the feedback for the > QEMU patches to handle machine check exception. Details > of earlier approach of handling machine check exception > in QEMU and related discussions can be found at: > > https://lists.nongnu.org/archive/html/qemu-devel/2014-11/msg00813.html > > This patch also introduces a new KVM capability to > control how KVM behaves on machine check exception. > Without this capability, KVM redirects machine check > exceptions to guest's 0x200 vector if the address in > error belongs to guest. With this capability KVM > causes a guest exit with NMI exit reason. > > This is required to avoid problems if a new kernel/KVM > is used with an old QEMU for guests that don't issue > "ibm,nmi-register". As old QEMU does not understand the > NMI exit type, it treats it as a fatal error. However, > the guest could have handled the machine check error > if the exception was delivered to guest's 0x200 interrupt > vector instead of NMI exit in case of old QEMU. > > Change Log v2: > - Added KVM capability > > Signed-off-by: Aravinda Prasad> --- > arch/powerpc/include/asm/kvm_host.h |1 + > arch/powerpc/kernel/asm-offsets.c |1 + > arch/powerpc/kvm/book3s_hv.c| 12 +++--- > arch/powerpc/kvm/book3s_hv_rmhandlers.S | 37 > +++ > arch/powerpc/kvm/powerpc.c |7 ++ > include/uapi/linux/kvm.h|1 + > 6 files changed, 31 insertions(+), 28 deletions(-) > > diff --git a/arch/powerpc/include/asm/kvm_host.h > b/arch/powerpc/include/asm/kvm_host.h > index 827a38d..8a652ba 100644 > --- a/arch/powerpc/include/asm/kvm_host.h > +++ b/arch/powerpc/include/asm/kvm_host.h > @@ -243,6 +243,7 @@ struct kvm_arch { > int hpt_cma_alloc; > struct dentry *debugfs_dir; > struct dentry *htab_dentry; > + u8 fwnmi_enabled; Here you declare the variable as 8-bits ... > #endif /* CONFIG_KVM_BOOK3S_HV_POSSIBLE */ > #ifdef CONFIG_KVM_BOOK3S_PR_POSSIBLE > struct mutex hpt_mutex; > diff --git a/arch/powerpc/kernel/asm-offsets.c > b/arch/powerpc/kernel/asm-offsets.c > index 221d584..6a4e81a 100644 > --- a/arch/powerpc/kernel/asm-offsets.c > +++ b/arch/powerpc/kernel/asm-offsets.c > @@ -506,6 +506,7 @@ int main(void) > DEFINE(KVM_ENABLED_HCALLS, offsetof(struct kvm, arch.enabled_hcalls)); > DEFINE(KVM_LPCR, offsetof(struct kvm, arch.lpcr)); > DEFINE(KVM_VRMA_SLB_V, offsetof(struct kvm, arch.vrma_slb_v)); > + DEFINE(KVM_FWNMI, offsetof(struct kvm, arch.fwnmi_enabled)); ... then define an asm-offset for it ... > DEFINE(VCPU_DSISR, offsetof(struct kvm_vcpu, arch.shregs.dsisr)); > DEFINE(VCPU_DAR, offsetof(struct kvm_vcpu, arch.shregs.dar)); > DEFINE(VCPU_VPA, offsetof(struct kvm_vcpu, arch.vpa.pinned_addr)); > diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S > b/arch/powerpc/kvm/book3s_hv_rmhandlers.S > index b98889e..f43c124 100644 > --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S > +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S [...] > @@ -2381,24 +2377,27 @@ machine_check_realmode: > ld r9, HSTATE_KVM_VCPU(r13) > li r12, BOOK3S_INTERRUPT_MACHINE_CHECK > /* > - * Deliver unhandled/fatal (e.g. UE) MCE errors to guest through > - * machine check interrupt (set HSRR0 to 0x200). And for handled > - * errors (no-fatal), just go back to guest execution with current > - * HSRR0 instead of exiting guest. This new approach will inject > - * machine check to guest for fatal error causing guest to crash. > - * > - * The old code used to return to host for unhandled errors which > - * was causing guest to hang with soft lockups inside guest and > - * makes it difficult to recover guest instance. > + * Deliver unhandled/fatal (e.g. UE) MCE errors to guest > + * by exiting the guest with KVM_EXIT_NMI exit reason (exit > + * reason set later based on trap). For handled errors > + * (no-fatal), go back to guest execution with current HSRR0 > + * instead of exiting the guest. This approach will cause > + * the guest to exit in case of fatal
Re: [PATCH v2] KVM: PPC: Exit guest upon fatal machine check exception
On 16/12/15 06:56, Aravinda Prasad wrote: > This patch modifies KVM to cause a guest exit with > KVM_EXIT_NMI instead of immediately delivering a 0x200 > interrupt to guest upon machine check exception in > guest address. Exiting the guest enables QEMU to build > error log and deliver machine check exception to guest > OS (either via guest OS registered machine check > handler or via 0x200 guest OS interrupt vector). > > This approach simplifies the delivering of machine > check exception to guest OS compared to the earlier approach > of KVM directly invoking 0x200 guest interrupt vector. > In the earlier approach QEMU patched the 0x200 interrupt > vector during boot. The patched code at 0x200 issued a > private hcall to pass the control to QEMU to build the > error log. > > This design/approach is based on the feedback for the > QEMU patches to handle machine check exception. Details > of earlier approach of handling machine check exception > in QEMU and related discussions can be found at: > > https://lists.nongnu.org/archive/html/qemu-devel/2014-11/msg00813.html > > This patch also introduces a new KVM capability to > control how KVM behaves on machine check exception. > Without this capability, KVM redirects machine check > exceptions to guest's 0x200 vector if the address in > error belongs to guest. With this capability KVM > causes a guest exit with NMI exit reason. > > This is required to avoid problems if a new kernel/KVM > is used with an old QEMU for guests that don't issue > "ibm,nmi-register". As old QEMU does not understand the > NMI exit type, it treats it as a fatal error. However, > the guest could have handled the machine check error > if the exception was delivered to guest's 0x200 interrupt > vector instead of NMI exit in case of old QEMU. > > Change Log v2: > - Added KVM capability > > Signed-off-by: Aravinda Prasad> --- > arch/powerpc/include/asm/kvm_host.h |1 + > arch/powerpc/kernel/asm-offsets.c |1 + > arch/powerpc/kvm/book3s_hv.c| 12 +++--- > arch/powerpc/kvm/book3s_hv_rmhandlers.S | 37 > +++ > arch/powerpc/kvm/powerpc.c |7 ++ > include/uapi/linux/kvm.h|1 + > 6 files changed, 31 insertions(+), 28 deletions(-) > > diff --git a/arch/powerpc/include/asm/kvm_host.h > b/arch/powerpc/include/asm/kvm_host.h > index 827a38d..8a652ba 100644 > --- a/arch/powerpc/include/asm/kvm_host.h > +++ b/arch/powerpc/include/asm/kvm_host.h > @@ -243,6 +243,7 @@ struct kvm_arch { > int hpt_cma_alloc; > struct dentry *debugfs_dir; > struct dentry *htab_dentry; > + u8 fwnmi_enabled; Here you declare the variable as 8-bits ... > #endif /* CONFIG_KVM_BOOK3S_HV_POSSIBLE */ > #ifdef CONFIG_KVM_BOOK3S_PR_POSSIBLE > struct mutex hpt_mutex; > diff --git a/arch/powerpc/kernel/asm-offsets.c > b/arch/powerpc/kernel/asm-offsets.c > index 221d584..6a4e81a 100644 > --- a/arch/powerpc/kernel/asm-offsets.c > +++ b/arch/powerpc/kernel/asm-offsets.c > @@ -506,6 +506,7 @@ int main(void) > DEFINE(KVM_ENABLED_HCALLS, offsetof(struct kvm, arch.enabled_hcalls)); > DEFINE(KVM_LPCR, offsetof(struct kvm, arch.lpcr)); > DEFINE(KVM_VRMA_SLB_V, offsetof(struct kvm, arch.vrma_slb_v)); > + DEFINE(KVM_FWNMI, offsetof(struct kvm, arch.fwnmi_enabled)); ... then define an asm-offset for it ... > DEFINE(VCPU_DSISR, offsetof(struct kvm_vcpu, arch.shregs.dsisr)); > DEFINE(VCPU_DAR, offsetof(struct kvm_vcpu, arch.shregs.dar)); > DEFINE(VCPU_VPA, offsetof(struct kvm_vcpu, arch.vpa.pinned_addr)); > diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S > b/arch/powerpc/kvm/book3s_hv_rmhandlers.S > index b98889e..f43c124 100644 > --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S > +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S [...] > @@ -2381,24 +2377,27 @@ machine_check_realmode: > ld r9, HSTATE_KVM_VCPU(r13) > li r12, BOOK3S_INTERRUPT_MACHINE_CHECK > /* > - * Deliver unhandled/fatal (e.g. UE) MCE errors to guest through > - * machine check interrupt (set HSRR0 to 0x200). And for handled > - * errors (no-fatal), just go back to guest execution with current > - * HSRR0 instead of exiting guest. This new approach will inject > - * machine check to guest for fatal error causing guest to crash. > - * > - * The old code used to return to host for unhandled errors which > - * was causing guest to hang with soft lockups inside guest and > - * makes it difficult to recover guest instance. > + * Deliver unhandled/fatal (e.g. UE) MCE errors to guest > + * by exiting the guest with KVM_EXIT_NMI exit reason (exit > + * reason set later based on trap). For handled errors > + * (no-fatal), go back to guest execution with current HSRR0 > + * instead of exiting the guest. This approach will cause > + * the guest to exit in case of fatal
[PATCH v2] KVM: PPC: Exit guest upon fatal machine check exception
This patch modifies KVM to cause a guest exit with KVM_EXIT_NMI instead of immediately delivering a 0x200 interrupt to guest upon machine check exception in guest address. Exiting the guest enables QEMU to build error log and deliver machine check exception to guest OS (either via guest OS registered machine check handler or via 0x200 guest OS interrupt vector). This approach simplifies the delivering of machine check exception to guest OS compared to the earlier approach of KVM directly invoking 0x200 guest interrupt vector. In the earlier approach QEMU patched the 0x200 interrupt vector during boot. The patched code at 0x200 issued a private hcall to pass the control to QEMU to build the error log. This design/approach is based on the feedback for the QEMU patches to handle machine check exception. Details of earlier approach of handling machine check exception in QEMU and related discussions can be found at: https://lists.nongnu.org/archive/html/qemu-devel/2014-11/msg00813.html This patch also introduces a new KVM capability to control how KVM behaves on machine check exception. Without this capability, KVM redirects machine check exceptions to guest's 0x200 vector if the address in error belongs to guest. With this capability KVM causes a guest exit with NMI exit reason. This is required to avoid problems if a new kernel/KVM is used with an old QEMU for guests that don't issue "ibm,nmi-register". As old QEMU does not understand the NMI exit type, it treats it as a fatal error. However, the guest could have handled the machine check error if the exception was delivered to guest's 0x200 interrupt vector instead of NMI exit in case of old QEMU. Change Log v2: - Added KVM capability Signed-off-by: Aravinda Prasad--- arch/powerpc/include/asm/kvm_host.h |1 + arch/powerpc/kernel/asm-offsets.c |1 + arch/powerpc/kvm/book3s_hv.c| 12 +++--- arch/powerpc/kvm/book3s_hv_rmhandlers.S | 37 +++ arch/powerpc/kvm/powerpc.c |7 ++ include/uapi/linux/kvm.h|1 + 6 files changed, 31 insertions(+), 28 deletions(-) diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h index 827a38d..8a652ba 100644 --- a/arch/powerpc/include/asm/kvm_host.h +++ b/arch/powerpc/include/asm/kvm_host.h @@ -243,6 +243,7 @@ struct kvm_arch { int hpt_cma_alloc; struct dentry *debugfs_dir; struct dentry *htab_dentry; + u8 fwnmi_enabled; #endif /* CONFIG_KVM_BOOK3S_HV_POSSIBLE */ #ifdef CONFIG_KVM_BOOK3S_PR_POSSIBLE struct mutex hpt_mutex; diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c index 221d584..6a4e81a 100644 --- a/arch/powerpc/kernel/asm-offsets.c +++ b/arch/powerpc/kernel/asm-offsets.c @@ -506,6 +506,7 @@ int main(void) DEFINE(KVM_ENABLED_HCALLS, offsetof(struct kvm, arch.enabled_hcalls)); DEFINE(KVM_LPCR, offsetof(struct kvm, arch.lpcr)); DEFINE(KVM_VRMA_SLB_V, offsetof(struct kvm, arch.vrma_slb_v)); + DEFINE(KVM_FWNMI, offsetof(struct kvm, arch.fwnmi_enabled)); DEFINE(VCPU_DSISR, offsetof(struct kvm_vcpu, arch.shregs.dsisr)); DEFINE(VCPU_DAR, offsetof(struct kvm_vcpu, arch.shregs.dar)); DEFINE(VCPU_VPA, offsetof(struct kvm_vcpu, arch.vpa.pinned_addr)); diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index 2280497..1b1dff0 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -859,15 +859,9 @@ static int kvmppc_handle_exit_hv(struct kvm_run *run, struct kvm_vcpu *vcpu, r = RESUME_GUEST; break; case BOOK3S_INTERRUPT_MACHINE_CHECK: - /* -* Deliver a machine check interrupt to the guest. -* We have to do this, even if the host has handled the -* machine check, because machine checks use SRR0/1 and -* the interrupt might have trashed guest state in them. -*/ - kvmppc_book3s_queue_irqprio(vcpu, - BOOK3S_INTERRUPT_MACHINE_CHECK); - r = RESUME_GUEST; + /* Exit to guest with KVM_EXIT_NMI as exit reason */ + run->exit_reason = KVM_EXIT_NMI; + r = RESUME_HOST; break; case BOOK3S_INTERRUPT_PROGRAM: { diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S index b98889e..f43c124 100644 --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S @@ -147,7 +147,6 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S) addir1, r1, 112 ld r7, HSTATE_HOST_MSR(r13) - cmpwi cr1, r12, BOOK3S_INTERRUPT_MACHINE_CHECK cmpwi r12, BOOK3S_INTERRUPT_EXTERNAL beq 11f cmpwi cr2, r12, BOOK3S_INTERRUPT_HMI @@
[PATCH v2] KVM: PPC: Exit guest upon fatal machine check exception
This patch modifies KVM to cause a guest exit with KVM_EXIT_NMI instead of immediately delivering a 0x200 interrupt to guest upon machine check exception in guest address. Exiting the guest enables QEMU to build error log and deliver machine check exception to guest OS (either via guest OS registered machine check handler or via 0x200 guest OS interrupt vector). This approach simplifies the delivering of machine check exception to guest OS compared to the earlier approach of KVM directly invoking 0x200 guest interrupt vector. In the earlier approach QEMU patched the 0x200 interrupt vector during boot. The patched code at 0x200 issued a private hcall to pass the control to QEMU to build the error log. This design/approach is based on the feedback for the QEMU patches to handle machine check exception. Details of earlier approach of handling machine check exception in QEMU and related discussions can be found at: https://lists.nongnu.org/archive/html/qemu-devel/2014-11/msg00813.html This patch also introduces a new KVM capability to control how KVM behaves on machine check exception. Without this capability, KVM redirects machine check exceptions to guest's 0x200 vector if the address in error belongs to guest. With this capability KVM causes a guest exit with NMI exit reason. This is required to avoid problems if a new kernel/KVM is used with an old QEMU for guests that don't issue "ibm,nmi-register". As old QEMU does not understand the NMI exit type, it treats it as a fatal error. However, the guest could have handled the machine check error if the exception was delivered to guest's 0x200 interrupt vector instead of NMI exit in case of old QEMU. Change Log v2: - Added KVM capability Signed-off-by: Aravinda Prasad--- arch/powerpc/include/asm/kvm_host.h |1 + arch/powerpc/kernel/asm-offsets.c |1 + arch/powerpc/kvm/book3s_hv.c| 12 +++--- arch/powerpc/kvm/book3s_hv_rmhandlers.S | 37 +++ arch/powerpc/kvm/powerpc.c |7 ++ include/uapi/linux/kvm.h|1 + 6 files changed, 31 insertions(+), 28 deletions(-) diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h index 827a38d..8a652ba 100644 --- a/arch/powerpc/include/asm/kvm_host.h +++ b/arch/powerpc/include/asm/kvm_host.h @@ -243,6 +243,7 @@ struct kvm_arch { int hpt_cma_alloc; struct dentry *debugfs_dir; struct dentry *htab_dentry; + u8 fwnmi_enabled; #endif /* CONFIG_KVM_BOOK3S_HV_POSSIBLE */ #ifdef CONFIG_KVM_BOOK3S_PR_POSSIBLE struct mutex hpt_mutex; diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c index 221d584..6a4e81a 100644 --- a/arch/powerpc/kernel/asm-offsets.c +++ b/arch/powerpc/kernel/asm-offsets.c @@ -506,6 +506,7 @@ int main(void) DEFINE(KVM_ENABLED_HCALLS, offsetof(struct kvm, arch.enabled_hcalls)); DEFINE(KVM_LPCR, offsetof(struct kvm, arch.lpcr)); DEFINE(KVM_VRMA_SLB_V, offsetof(struct kvm, arch.vrma_slb_v)); + DEFINE(KVM_FWNMI, offsetof(struct kvm, arch.fwnmi_enabled)); DEFINE(VCPU_DSISR, offsetof(struct kvm_vcpu, arch.shregs.dsisr)); DEFINE(VCPU_DAR, offsetof(struct kvm_vcpu, arch.shregs.dar)); DEFINE(VCPU_VPA, offsetof(struct kvm_vcpu, arch.vpa.pinned_addr)); diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index 2280497..1b1dff0 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -859,15 +859,9 @@ static int kvmppc_handle_exit_hv(struct kvm_run *run, struct kvm_vcpu *vcpu, r = RESUME_GUEST; break; case BOOK3S_INTERRUPT_MACHINE_CHECK: - /* -* Deliver a machine check interrupt to the guest. -* We have to do this, even if the host has handled the -* machine check, because machine checks use SRR0/1 and -* the interrupt might have trashed guest state in them. -*/ - kvmppc_book3s_queue_irqprio(vcpu, - BOOK3S_INTERRUPT_MACHINE_CHECK); - r = RESUME_GUEST; + /* Exit to guest with KVM_EXIT_NMI as exit reason */ + run->exit_reason = KVM_EXIT_NMI; + r = RESUME_HOST; break; case BOOK3S_INTERRUPT_PROGRAM: { diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S index b98889e..f43c124 100644 --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S @@ -147,7 +147,6 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S) addir1, r1, 112 ld r7, HSTATE_HOST_MSR(r13) - cmpwi cr1, r12, BOOK3S_INTERRUPT_MACHINE_CHECK cmpwi r12, BOOK3S_INTERRUPT_EXTERNAL beq 11f cmpwi cr2, r12, BOOK3S_INTERRUPT_HMI @@
Re: [PATCH v2] KVM: PPC: Exit guest upon fatal machine check exception
Hi, > This patch also introduces a new KVM capability to > control how KVM behaves on machine check exception. > Without this capability, KVM redirects machine check > exceptions to guest's 0x200 vector if the address in > error belongs to guest. With this capability KVM > causes a guest exit with NMI exit reason. > > This is required to avoid problems if a new kernel/KVM > is used with an old QEMU for guests that don't issue > "ibm,nmi-register". As old QEMU does not understand the > NMI exit type, it treats it as a fatal error. However, > the guest could have handled the machine check error > if the exception was delivered to guest's 0x200 interrupt > vector instead of NMI exit in case of old QEMU. > > Change Log v2: > - Added KVM capability I'm not really qualified to review the contents of this patch, but I'm happy that the changes in v2 address the concern I had for version 1: thank you. Regards, Daniel > > Signed-off-by: Aravinda Prasad> --- > arch/powerpc/include/asm/kvm_host.h |1 + > arch/powerpc/kernel/asm-offsets.c |1 + > arch/powerpc/kvm/book3s_hv.c| 12 +++--- > arch/powerpc/kvm/book3s_hv_rmhandlers.S | 37 > +++ > arch/powerpc/kvm/powerpc.c |7 ++ > include/uapi/linux/kvm.h|1 + > 6 files changed, 31 insertions(+), 28 deletions(-) > > diff --git a/arch/powerpc/include/asm/kvm_host.h > b/arch/powerpc/include/asm/kvm_host.h > index 827a38d..8a652ba 100644 > --- a/arch/powerpc/include/asm/kvm_host.h > +++ b/arch/powerpc/include/asm/kvm_host.h > @@ -243,6 +243,7 @@ struct kvm_arch { > int hpt_cma_alloc; > struct dentry *debugfs_dir; > struct dentry *htab_dentry; > + u8 fwnmi_enabled; > #endif /* CONFIG_KVM_BOOK3S_HV_POSSIBLE */ > #ifdef CONFIG_KVM_BOOK3S_PR_POSSIBLE > struct mutex hpt_mutex; > diff --git a/arch/powerpc/kernel/asm-offsets.c > b/arch/powerpc/kernel/asm-offsets.c > index 221d584..6a4e81a 100644 > --- a/arch/powerpc/kernel/asm-offsets.c > +++ b/arch/powerpc/kernel/asm-offsets.c > @@ -506,6 +506,7 @@ int main(void) > DEFINE(KVM_ENABLED_HCALLS, offsetof(struct kvm, arch.enabled_hcalls)); > DEFINE(KVM_LPCR, offsetof(struct kvm, arch.lpcr)); > DEFINE(KVM_VRMA_SLB_V, offsetof(struct kvm, arch.vrma_slb_v)); > + DEFINE(KVM_FWNMI, offsetof(struct kvm, arch.fwnmi_enabled)); > DEFINE(VCPU_DSISR, offsetof(struct kvm_vcpu, arch.shregs.dsisr)); > DEFINE(VCPU_DAR, offsetof(struct kvm_vcpu, arch.shregs.dar)); > DEFINE(VCPU_VPA, offsetof(struct kvm_vcpu, arch.vpa.pinned_addr)); > diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c > index 2280497..1b1dff0 100644 > --- a/arch/powerpc/kvm/book3s_hv.c > +++ b/arch/powerpc/kvm/book3s_hv.c > @@ -859,15 +859,9 @@ static int kvmppc_handle_exit_hv(struct kvm_run *run, > struct kvm_vcpu *vcpu, > r = RESUME_GUEST; > break; > case BOOK3S_INTERRUPT_MACHINE_CHECK: > - /* > - * Deliver a machine check interrupt to the guest. > - * We have to do this, even if the host has handled the > - * machine check, because machine checks use SRR0/1 and > - * the interrupt might have trashed guest state in them. > - */ > - kvmppc_book3s_queue_irqprio(vcpu, > - BOOK3S_INTERRUPT_MACHINE_CHECK); > - r = RESUME_GUEST; > + /* Exit to guest with KVM_EXIT_NMI as exit reason */ > + run->exit_reason = KVM_EXIT_NMI; > + r = RESUME_HOST; > break; > case BOOK3S_INTERRUPT_PROGRAM: > { > diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S > b/arch/powerpc/kvm/book3s_hv_rmhandlers.S > index b98889e..f43c124 100644 > --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S > +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S > @@ -147,7 +147,6 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S) > addir1, r1, 112 > ld r7, HSTATE_HOST_MSR(r13) > > - cmpwi cr1, r12, BOOK3S_INTERRUPT_MACHINE_CHECK > cmpwi r12, BOOK3S_INTERRUPT_EXTERNAL > beq 11f > cmpwi cr2, r12, BOOK3S_INTERRUPT_HMI > @@ -160,7 +159,6 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S) > mtmsrd r6, 1 /* Clear RI in MSR */ > mtsrr0 r8 > mtsrr1 r7 > - beq cr1, 13f/* machine check */ > RFI > > /* On POWER7, we have external interrupts set to use HSRR0/1 */ > @@ -168,8 +166,6 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S) > mtspr SPRN_HSRR1, r7 > ba 0x500 > > -13: b machine_check_fwnmi > - > 14: mtspr SPRN_HSRR0, r8 > mtspr SPRN_HSRR1, r7 > b hmi_exception_after_realmode > @@ -2381,24 +2377,27 @@ machine_check_realmode: > ld r9, HSTATE_KVM_VCPU(r13) > li r12, BOOK3S_INTERRUPT_MACHINE_CHECK >
Re: [PATCH v2] KVM: PPC: Exit guest upon fatal machine check exception
Hi, > This patch also introduces a new KVM capability to > control how KVM behaves on machine check exception. > Without this capability, KVM redirects machine check > exceptions to guest's 0x200 vector if the address in > error belongs to guest. With this capability KVM > causes a guest exit with NMI exit reason. > > This is required to avoid problems if a new kernel/KVM > is used with an old QEMU for guests that don't issue > "ibm,nmi-register". As old QEMU does not understand the > NMI exit type, it treats it as a fatal error. However, > the guest could have handled the machine check error > if the exception was delivered to guest's 0x200 interrupt > vector instead of NMI exit in case of old QEMU. > > Change Log v2: > - Added KVM capability I'm not really qualified to review the contents of this patch, but I'm happy that the changes in v2 address the concern I had for version 1: thank you. Regards, Daniel > > Signed-off-by: Aravinda Prasad> --- > arch/powerpc/include/asm/kvm_host.h |1 + > arch/powerpc/kernel/asm-offsets.c |1 + > arch/powerpc/kvm/book3s_hv.c| 12 +++--- > arch/powerpc/kvm/book3s_hv_rmhandlers.S | 37 > +++ > arch/powerpc/kvm/powerpc.c |7 ++ > include/uapi/linux/kvm.h|1 + > 6 files changed, 31 insertions(+), 28 deletions(-) > > diff --git a/arch/powerpc/include/asm/kvm_host.h > b/arch/powerpc/include/asm/kvm_host.h > index 827a38d..8a652ba 100644 > --- a/arch/powerpc/include/asm/kvm_host.h > +++ b/arch/powerpc/include/asm/kvm_host.h > @@ -243,6 +243,7 @@ struct kvm_arch { > int hpt_cma_alloc; > struct dentry *debugfs_dir; > struct dentry *htab_dentry; > + u8 fwnmi_enabled; > #endif /* CONFIG_KVM_BOOK3S_HV_POSSIBLE */ > #ifdef CONFIG_KVM_BOOK3S_PR_POSSIBLE > struct mutex hpt_mutex; > diff --git a/arch/powerpc/kernel/asm-offsets.c > b/arch/powerpc/kernel/asm-offsets.c > index 221d584..6a4e81a 100644 > --- a/arch/powerpc/kernel/asm-offsets.c > +++ b/arch/powerpc/kernel/asm-offsets.c > @@ -506,6 +506,7 @@ int main(void) > DEFINE(KVM_ENABLED_HCALLS, offsetof(struct kvm, arch.enabled_hcalls)); > DEFINE(KVM_LPCR, offsetof(struct kvm, arch.lpcr)); > DEFINE(KVM_VRMA_SLB_V, offsetof(struct kvm, arch.vrma_slb_v)); > + DEFINE(KVM_FWNMI, offsetof(struct kvm, arch.fwnmi_enabled)); > DEFINE(VCPU_DSISR, offsetof(struct kvm_vcpu, arch.shregs.dsisr)); > DEFINE(VCPU_DAR, offsetof(struct kvm_vcpu, arch.shregs.dar)); > DEFINE(VCPU_VPA, offsetof(struct kvm_vcpu, arch.vpa.pinned_addr)); > diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c > index 2280497..1b1dff0 100644 > --- a/arch/powerpc/kvm/book3s_hv.c > +++ b/arch/powerpc/kvm/book3s_hv.c > @@ -859,15 +859,9 @@ static int kvmppc_handle_exit_hv(struct kvm_run *run, > struct kvm_vcpu *vcpu, > r = RESUME_GUEST; > break; > case BOOK3S_INTERRUPT_MACHINE_CHECK: > - /* > - * Deliver a machine check interrupt to the guest. > - * We have to do this, even if the host has handled the > - * machine check, because machine checks use SRR0/1 and > - * the interrupt might have trashed guest state in them. > - */ > - kvmppc_book3s_queue_irqprio(vcpu, > - BOOK3S_INTERRUPT_MACHINE_CHECK); > - r = RESUME_GUEST; > + /* Exit to guest with KVM_EXIT_NMI as exit reason */ > + run->exit_reason = KVM_EXIT_NMI; > + r = RESUME_HOST; > break; > case BOOK3S_INTERRUPT_PROGRAM: > { > diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S > b/arch/powerpc/kvm/book3s_hv_rmhandlers.S > index b98889e..f43c124 100644 > --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S > +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S > @@ -147,7 +147,6 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S) > addir1, r1, 112 > ld r7, HSTATE_HOST_MSR(r13) > > - cmpwi cr1, r12, BOOK3S_INTERRUPT_MACHINE_CHECK > cmpwi r12, BOOK3S_INTERRUPT_EXTERNAL > beq 11f > cmpwi cr2, r12, BOOK3S_INTERRUPT_HMI > @@ -160,7 +159,6 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S) > mtmsrd r6, 1 /* Clear RI in MSR */ > mtsrr0 r8 > mtsrr1 r7 > - beq cr1, 13f/* machine check */ > RFI > > /* On POWER7, we have external interrupts set to use HSRR0/1 */ > @@ -168,8 +166,6 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S) > mtspr SPRN_HSRR1, r7 > ba 0x500 > > -13: b machine_check_fwnmi > - > 14: mtspr SPRN_HSRR0, r8 > mtspr SPRN_HSRR1, r7 > b hmi_exception_after_realmode > @@ -2381,24 +2377,27 @@ machine_check_realmode: > ld r9, HSTATE_KVM_VCPU(r13) > li r12, BOOK3S_INTERRUPT_MACHINE_CHECK >