Re: [PATCH v5 06/14] KVM: ARM: Inject IRQs and FIQs from userspace

Gleb Natapov
2013-01-15T09:56:41Z

On Tue, Jan 08, 2013 at 01:39:17PM -0500, Christoffer Dall wrote:
> From: Christoffer Dall <cdall@cs.columbia.edu>
>
> All interrupt injection is now based on the VM ioctl KVM_IRQ_LINE. This
> works semantically well for the GIC as we in fact raise/lower a line on
> a machine component (the gic). The IOCTL uses the follwing struct.
>
> struct kvm_irq_level {
> union {
> __u32 irq; /* GSI */
> __s32 status; /* not used for KVM_IRQ_LEVEL */
> };
> __u32 level; /* 0 or 1 */
> };
>
> ARM can signal an interrupt either at the CPU level, or at the in-kernel irqchip
CPU level interrupt should use KVM_INTERRUPT instead.

> (GIC), and for in-kernel irqchip can tell the GIC to use PPIs designated for
> specific cpus. The irq field is interpreted like this:
>
Haven't read about GIC yet. Is PPI an interrupt that device can send
directly to a specific CPU? Can we model that with irq routing like we do
for MSI?

>  bits: | 31 ... 24 | 23 ... 16 | 15 ... 0 |
> field: | irq_type | vcpu_index | irq_number |
>
> The irq_type field has the following values:
> - irq_type[0]: out-of-kernel GIC: irq_number 0 is IRQ, irq_number 1 is FIQ
> - irq_type[1]: in-kernel GIC: SPI, irq_number between 32 and 1019 (incl.)
> (the vcpu_index field is ignored)
> - irq_type[2]: in-kernel GIC: PPI, irq_number between 16 and 31 (incl.)
>
> The irq_number thus corresponds to the irq ID in as in the GICv2 specs.
>
> This is documented in Documentation/kvm/api.txt.
>
> Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com>
> Signed-off-by: Christoffer Dall <c.dall@virtualopensystems.com>
> ---
> Documentation/virtual/kvm/api.txt | 25 ++++++++++++--
> arch/arm/include/asm/kvm_arm.h | 1 +
> arch/arm/include/uapi/asm/kvm.h | 21 ++++++++++++
> arch/arm/kvm/arm.c | 65 +++++++++++++++++++++++++++++++++++++
> arch/arm/kvm/trace.h | 25 ++++++++++++++
> include/uapi/linux/kvm.h | 1 +
> 6 files changed, 134 insertions(+), 4 deletions(-)
>
> diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
> index 4237c27..5050492 100644
> --- a/Documentation/virtual/kvm/api.txt
> +++ b/Documentation/virtual/kvm/api.txt
> @@ -615,15 +615,32 @@ created.
> 4.25 KVM_IRQ_LINE
>
> Capability: KVM_CAP_IRQCHIP
> -Architectures: x86, ia64
> +Architectures: x86, ia64, arm
> Type: vm ioctl
> Parameters: struct kvm_irq_level
> Returns: 0 on success, -1 on error
>
> Sets the level of a GSI input to the interrupt controller model in the kernel.
> -Requires 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 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.
> +
> +ARM 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 like this:
> +
> +  bits: | 31 ... 24 | 23 ... 16 | 15 ... 0 |
> + field: | irq_type | vcpu_index | irq_id |
> +
> +The irq_type field has the following values:
> +- irq_type[0]: out-of-kernel GIC: irq_id 0 is IRQ, irq_id 1 is FIQ
> +- irq_type[1]: in-kernel GIC: SPI, irq_id between 32 and 1019 (incl.)
> + (the vcpu_index field is ignored)
> +- irq_type[2]: in-kernel GIC: PPI, irq_id between 16 and 31 (incl.)
> +
> +(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.
>
> struct kvm_irq_level {
> union {
> diff --git a/arch/arm/include/asm/kvm_arm.h b/arch/arm/include/asm/kvm_arm.h
> index 613afe2..fb22ee8 100644
> --- a/arch/arm/include/asm/kvm_arm.h
> +++ b/arch/arm/include/asm/kvm_arm.h
> @@ -68,6 +68,7 @@
> #define HCR_GUEST_MASK (HCR_TSC | HCR_TSW | HCR_TWI | HCR_VM | HCR_BSU_IS | \
> HCR_FB | HCR_TAC | HCR_AMO | HCR_IMO | HCR_FMO | \
> HCR_SWIO | HCR_TIDCP)
> +#define HCR_VIRT_EXCP_MASK (HCR_VA | HCR_VI | HCR_VF)
>
> /* Hyp System Control Register (HSCTLR) bits */
> #define HSCTLR_TE (1 << 30)
> diff --git a/arch/arm/include/uapi/asm/kvm.h b/arch/arm/include/uapi/asm/kvm.h
> index c6298b1..4cf6d8f 100644
> --- a/arch/arm/include/uapi/asm/kvm.h
> +++ b/arch/arm/include/uapi/asm/kvm.h
> @@ -23,6 +23,7 @@
> #include <asm/ptrace.h>
>
> #define __KVM_HAVE_GUEST_DEBUG
> +#define __KVM_HAVE_IRQ_LINE
>
> #define KVM_REG_SIZE(id) \
> (1U << (((id) & KVM_REG_SIZE_MASK) >> KVM_REG_SIZE_SHIFT))
> @@ -103,4 +104,24 @@ struct kvm_arch_memory_slot {
> #define KVM_REG_ARM_CORE (0x0010 << KVM_REG_ARM_COPROC_SHIFT)
> #define KVM_REG_ARM_CORE_REG(name) (offsetof(struct kvm_regs, name) / 4)
>
> +/* KVM_IRQ_LINE irq field index values */
> +#define KVM_ARM_IRQ_TYPE_SHIFT 24
> +#define KVM_ARM_IRQ_TYPE_MASK 0xff
> +#define KVM_ARM_IRQ_VCPU_SHIFT 16
> +#define KVM_ARM_IRQ_VCPU_MASK 0xff
> +#define KVM_ARM_IRQ_NUM_SHIFT 0
> +#define KVM_ARM_IRQ_NUM_MASK 0xffff
> +
> +/* irq_type field */
> +#define KVM_ARM_IRQ_TYPE_CPU 0
> +#define KVM_ARM_IRQ_TYPE_SPI 1
> +#define KVM_ARM_IRQ_TYPE_PPI 2
> +
> +/* out-of-kernel GIC cpu interrupt injection irq_number field */
> +#define KVM_ARM_IRQ_CPU_IRQ 0
> +#define KVM_ARM_IRQ_CPU_FIQ 1
> +
> +/* Highest supported SPI, from VGIC_NR_IRQS */
> +#define KVM_ARM_IRQ_GIC_MAX 127
> +
> #endif /* __ARM_KVM_H__ */
> diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
> index ab82039..9b4566e 100644
> --- a/arch/arm/kvm/arm.c
> +++ b/arch/arm/kvm/arm.c
> @@ -24,6 +24,7 @@
> #include <linux/fs.h>
> #include <linux/mman.h>
> #include <linux/sched.h>
> +#include <linux/kvm.h>
> #include <trace/events/kvm.h>
>
> #define CREATE_TRACE_POINTS
> @@ -284,6 +285,7 @@ void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu)
>
> void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
> {
> + vcpu->cpu = cpu;
> }
>
> void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
> @@ -324,6 +326,69 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
> return -EINVAL;
> }
>
> +static int vcpu_interrupt_line(struct kvm_vcpu *vcpu, int number, bool level)
> +{
> + int bit_index;
> + bool set;
> + unsigned long *ptr;
> +
> + if (number == KVM_ARM_IRQ_CPU_IRQ)
> + bit_index = __ffs(HCR_VI);
> + else /* KVM_ARM_IRQ_CPU_FIQ */
> + bit_index = __ffs(HCR_VF);
> +
> + ptr = (unsigned long *)&vcpu->arch.irq_lines;
> + if (level)
> + set = test_and_set_bit(bit_index, ptr);
> + else
> + set = test_and_clear_bit(bit_index, ptr);
> +
> + /*
> + * If we didn't change anything, no need to wake up or kick other CPUs
> + */
> + if (set == level)
> + return 0;
> +
> + /*
> + * The vcpu irq_lines field was updated, wake up sleeping VCPUs and
> + * trigger a world-switch round on the running physical CPU to set the
> + * virtual IRQ/FIQ fields in the HCR appropriately.
> + */
> + kvm_vcpu_kick(vcpu);
> +
> + return 0;
> +}
> +
> +int kvm_vm_ioctl_irq_line(struct kvm *kvm, struct kvm_irq_level *irq_level)
> +{
> + u32 irq = irq_level->irq;
> + unsigned int irq_type, vcpu_idx, irq_num;
> + int nrcpus = atomic_read(&kvm->online_vcpus);
> + struct kvm_vcpu *vcpu = NULL;
> + bool level = irq_level->level;
> +
> + irq_type = (irq >> KVM_ARM_IRQ_TYPE_SHIFT) & KVM_ARM_IRQ_TYPE_MASK;
> + vcpu_idx = (irq >> KVM_ARM_IRQ_VCPU_SHIFT) & KVM_ARM_IRQ_VCPU_MASK;
> + irq_num = (irq >> KVM_ARM_IRQ_NUM_SHIFT) & KVM_ARM_IRQ_NUM_MASK;
> +
> + trace_kvm_irq_line(irq_type, vcpu_idx, irq_num, irq_level->level);
> +
> + if (irq_type != KVM_ARM_IRQ_TYPE_CPU)
> + return -EINVAL;
> +
> + if (vcpu_idx >= nrcpus)
> + return -EINVAL;
> +
> + vcpu = kvm_get_vcpu(kvm, vcpu_idx);
> + if (!vcpu)
> + return -EINVAL;
> +
> + if (irq_num > KVM_ARM_IRQ_CPU_FIQ)
> + return -EINVAL;
> +
> + return vcpu_interrupt_line(vcpu, irq_num, level);
> +}
> +
> long kvm_arch_vcpu_ioctl(struct file *filp,
> unsigned int ioctl, unsigned long arg)
> {
> diff --git a/arch/arm/kvm/trace.h b/arch/arm/kvm/trace.h
> index 862b2cc..105d1f7 100644
> --- a/arch/arm/kvm/trace.h
> +++ b/arch/arm/kvm/trace.h
> @@ -39,6 +39,31 @@ TRACE_EVENT(kvm_exit,
> TP_printk("PC: 0x%08lx", __entry->vcpu_pc)
> );
>
> +TRACE_EVENT(kvm_irq_line,
> + TP_PROTO(unsigned int type, int vcpu_idx, int irq_num, int level),
> + TP_ARGS(type, vcpu_idx, irq_num, level),
> +
> + TP_STRUCT__entry(
> + __field( unsigned int, type )
> + __field( int, vcpu_idx )
> + __field( int, irq_num )
> + __field( int, level )
> + ),
> +
> + TP_fast_assign(
> + __entry->type = type;
> + __entry->vcpu_idx = vcpu_idx;
> + __entry->irq_num = irq_num;
> + __entry->level = level;
> + ),
> +
> + TP_printk("Inject %s interrupt (%d), vcpu->idx: %d, num: %d, level: %d",
> + (__entry->type == KVM_ARM_IRQ_TYPE_CPU) ? "CPU" :
> + (__entry->type == KVM_ARM_IRQ_TYPE_PPI) ? "VGIC PPI" :
> + (__entry->type == KVM_ARM_IRQ_TYPE_SPI) ? "VGIC SPI" : "UNKNOWN",
> + __entry->type, __entry->vcpu_idx, __entry->irq_num, __entry->level)
> +);
> +
> TRACE_EVENT(kvm_unmap_hva,
> TP_PROTO(unsigned long hva),
> TP_ARGS(hva),
> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> index 24978d5..dc63665 100644
> --- a/include/uapi/linux/kvm.h
> +++ b/include/uapi/linux/kvm.h
> @@ -115,6 +115,7 @@ struct kvm_irq_level {
> * ACPI gsi notion of irq.
> * For IA-64 (APIC model) IOAPIC0: irq 0-23; IOAPIC1: irq 24-47..
> * For X86 (standard AT mode) PIC0/1: irq 0-15. IOAPIC0: 0-23..
> + * For ARM: See Documentation/virtual/kvm/api.txt
> */
> union {
> __u32 irq;
>
> --
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--
Gleb.