| Message ID | 148396203530.1471.16105350692124392705.stgit@aravinda (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
On Mon, Jan 09, 2017 at 05:10:35PM +0530, Aravinda Prasad wrote: > This patch introduces a new KVM capability to control > how KVM behaves on machine check exception (MCE). > Without this capability, KVM redirects machine check > exceptions to guest's 0x200 vector, if the address in > error belongs to the guest. With this capability KVM > causes a guest exit with NMI exit reason. > > The new capability 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. > Can you move these to a cover letter, the description here does not match the changes > QEMU part can be found at: > http://lists.nongnu.org/archive/html/qemu-ppc/2015-12/msg00199.html > Balbir Singh.
On Mon, Jan 09, 2017 at 05:10:35PM +0530, Aravinda Prasad wrote: > This patch introduces a new KVM capability to control > how KVM behaves on machine check exception (MCE). > Without this capability, KVM redirects machine check > exceptions to guest's 0x200 vector, if the address in > error belongs to the guest. With this capability KVM > causes a guest exit with NMI exit reason. > > The new capability 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. You need to add a description of the new capability to Documentation/virtual/kvm/api.txt. Paul.
On Thursday 12 January 2017 03:26 PM, Paul Mackerras wrote: > On Mon, Jan 09, 2017 at 05:10:35PM +0530, Aravinda Prasad wrote: >> This patch introduces a new KVM capability to control >> how KVM behaves on machine check exception (MCE). >> Without this capability, KVM redirects machine check >> exceptions to guest's 0x200 vector, if the address in >> error belongs to the guest. With this capability KVM >> causes a guest exit with NMI exit reason. >> >> The new capability 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. > > You need to add a description of the new capability to > Documentation/virtual/kvm/api.txt. sure. > > Paul. >
diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h index 28350a2..018c684 100644 --- a/arch/powerpc/include/asm/kvm_host.h +++ b/arch/powerpc/include/asm/kvm_host.h @@ -264,6 +264,7 @@ 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 caec7bf..3acd503 100644 --- a/arch/powerpc/kernel/asm-offsets.c +++ b/arch/powerpc/kernel/asm-offsets.c @@ -494,6 +494,7 @@ int main(void) DEFINE(KVM_NEED_FLUSH, offsetof(struct kvm, arch.need_tlb_flush.bits)); DEFINE(KVM_ENABLED_HCALLS, offsetof(struct kvm, arch.enabled_hcalls)); 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/powerpc.c b/arch/powerpc/kvm/powerpc.c index 70963c8..a4405a8 100644 --- a/arch/powerpc/kvm/powerpc.c +++ b/arch/powerpc/kvm/powerpc.c @@ -604,6 +604,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) r = cpu_has_feature(CPU_FTR_TM_COMP) && is_kvmppc_hv_enabled(kvm); break; + case KVM_CAP_PPC_FWNMI: + r = 1; + break; default: r = 0; break; @@ -1204,6 +1207,10 @@ static int kvm_vcpu_ioctl_enable_cap(struct kvm_vcpu *vcpu, break; } #endif /* CONFIG_KVM_XICS */ + case KVM_CAP_PPC_FWNMI: + r = 0; + vcpu->kvm->arch.fwnmi_enabled = true; + break; default: r = -EINVAL; break; diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index 4ee67cb..3e41c42 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -870,6 +870,7 @@ struct kvm_ppc_smmu_info { #define KVM_CAP_S390_USER_INSTR0 130 #define KVM_CAP_MSI_DEVID 131 #define KVM_CAP_PPC_HTM 132 +#define KVM_CAP_PPC_FWNMI 133 #ifdef KVM_CAP_IRQ_ROUTING
This patch introduces a new KVM capability to control how KVM behaves on machine check exception (MCE). Without this capability, KVM redirects machine check exceptions to guest's 0x200 vector, if the address in error belongs to the guest. With this capability KVM causes a guest exit with NMI exit reason. The new capability 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. QEMU part can be found at: http://lists.nongnu.org/archive/html/qemu-ppc/2015-12/msg00199.html Change Log v4: - Allow host-side handling of the machine check exception before passing on the exception to the guest. Change Log v3: - Split the patch into 2. First patch introduces the new capability while the second one enhances KVM to redirect MCE. - Fix access width bug Change Log v2: - Added KVM capability Signed-off-by: Aravinda Prasad <aravinda@linux.vnet.ibm.com> Reviewed-by: David Gibson <david@gibson.dropbear.id.au> --- arch/powerpc/include/asm/kvm_host.h | 1 + arch/powerpc/kernel/asm-offsets.c | 1 + arch/powerpc/kvm/powerpc.c | 7 +++++++ include/uapi/linux/kvm.h | 1 + 4 files changed, 10 insertions(+)