diff options
| -rw-r--r-- | Documentation/virtual/kvm/api.txt | 16 | ||||
| -rw-r--r-- | arch/ia64/kvm/kvm-ia64.c | 1 | ||||
| -rw-r--r-- | arch/x86/kvm/x86.c | 1 | ||||
| -rw-r--r-- | include/uapi/linux/kvm.h | 1 | ||||
| -rw-r--r-- | virt/kvm/ioapic.c | 1 |
5 files changed, 18 insertions, 2 deletions
diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt index 6cd63a9010fb..4714f282a43e 100644 --- a/Documentation/virtual/kvm/api.txt +++ b/Documentation/virtual/kvm/api.txt @@ -612,6 +612,20 @@ On some architectures it is required that an interrupt controller model has been previously created with KVM_CREATE_IRQCHIP. Note that edge-triggered interrupts require the level to be set to 1 and then back to 0. +On real hardware, interrupt pins can be active-low or active-high. This +does not matter for the level field of struct kvm_irq_level: 1 always +means active (asserted), 0 means inactive (deasserted). + +x86 allows the operating system to program the interrupt polarity +(active-low/active-high) for level-triggered interrupts, and KVM used +to consider the polarity. However, due to bitrot in the handling of +active-low interrupts, the above convention is now valid on x86 too. +This is signaled by KVM_CAP_X86_IOAPIC_POLARITY_IGNORED. Userspace +should not present interrupts to the guest as active-low unless this +capability is present (or unless it is not using the in-kernel irqchip, +of course). + + ARM/arm64 can signal an interrupt either at the CPU level, or at the in-kernel irqchip (GIC), and for in-kernel irqchip can tell the GIC to use PPIs designated for specific cpus. The irq field is interpreted @@ -628,7 +642,7 @@ The irq_type field has the following values: (The irq_id field thus corresponds nicely to the IRQ ID in the ARM GIC specs) -In both cases, level is used to raise/lower the line. +In both cases, level is used to assert/deassert the line. struct kvm_irq_level { union { diff --git a/arch/ia64/kvm/kvm-ia64.c b/arch/ia64/kvm/kvm-ia64.c index 53f44bee9ebb..6a4309bb821a 100644 --- a/arch/ia64/kvm/kvm-ia64.c +++ b/arch/ia64/kvm/kvm-ia64.c @@ -199,6 +199,7 @@ int kvm_dev_ioctl_check_extension(long ext) case KVM_CAP_IRQCHIP: case KVM_CAP_MP_STATE: case KVM_CAP_IRQ_INJECT_STATUS: + case KVM_CAP_IOAPIC_POLARITY_IGNORED: r = 1; break; case KVM_CAP_COALESCED_MMIO: diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index d906391a0a3f..a37da6b0165a 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -2657,6 +2657,7 @@ int kvm_dev_ioctl_check_extension(long ext) case KVM_CAP_KVMCLOCK_CTRL: case KVM_CAP_READONLY_MEM: case KVM_CAP_HYPERV_TIME: + case KVM_CAP_IOAPIC_POLARITY_IGNORED: #ifdef CONFIG_KVM_DEVICE_ASSIGNMENT case KVM_CAP_ASSIGN_DEV_IRQ: case KVM_CAP_PCI_2_3: diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index 7d76401d2bb5..a7518be31d53 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -740,6 +740,7 @@ struct kvm_ppc_smmu_info { #define KVM_CAP_SPAPR_MULTITCE 94 #define KVM_CAP_EXT_EMUL_CPUID 95 #define KVM_CAP_HYPERV_TIME 96 +#define KVM_CAP_IOAPIC_POLARITY_IGNORED 97 #ifdef KVM_CAP_IRQ_ROUTING diff --git a/virt/kvm/ioapic.c b/virt/kvm/ioapic.c index ce9ed99ad7dc..1539d3757a04 100644 --- a/virt/kvm/ioapic.c +++ b/virt/kvm/ioapic.c @@ -328,7 +328,6 @@ int kvm_ioapic_set_irq(struct kvm_ioapic *ioapic, int irq, int irq_source_id, irq_level = __kvm_irq_line_state(&ioapic->irq_states[irq], irq_source_id, level); entry = ioapic->redirtbl[irq]; - irq_level ^= entry.fields.polarity; if (!irq_level) { ioapic->irr &= ~mask; ret = 1; |