On 2012-08-16 17:29, Christoffer Dall wrote:
> From: Christoffer Dall <cdall@xxxxxxxxxxxxxxx>
>
> Userspace can inject IRQs and FIQs through the KVM_IRQ_LINE VM ioctl.
> This ioctl is used since the sematics are in fact two lines that can be
> either raised or lowered on the VCPU - the IRQ and FIQ lines.
>
> KVM needs to know which VCPU it must operate on and whether the FIQ or
> IRQ line is raised/lowered. Hence both pieces of information is packed
> in the kvm_irq_level->irq field. The irq fild value will be:
> IRQ: vcpu_index << 1
> FIQ: (vcpu_index << 1) | 1
>
> This is documented in Documentation/kvm/api.txt.
>
> The effect of the ioctl is simply to simply raise/lower the
> corresponding irq_line field on the VCPU struct, which will cause the
> world-switch code to raise/lower virtual interrupts when running the
> guest on next switch. The wait_for_interrupt flag is also cleared for
> raised IRQs or FIQs causing an idle VCPU to become active again. CPUs
> in guest mode are kicked to make sure they refresh their interrupt status.
>
> Signed-off-by: Christoffer Dall <c.dall@xxxxxxxxxxxxxxxxxxxxxx>
> ---
> Documentation/virtual/kvm/api.txt | 12 ++++++---
> arch/arm/include/asm/kvm.h | 9 +++++++
> arch/arm/include/asm/kvm_arm.h | 1 +
> arch/arm/kvm/arm.c | 47 +++++++++++++++++++++++++++++++++++++
> include/linux/kvm.h | 1 +
> 5 files changed, 66 insertions(+), 4 deletions(-)
>
> diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
> index bf33aaa..8345b78 100644
> --- a/Documentation/virtual/kvm/api.txt
> +++ b/Documentation/virtual/kvm/api.txt
> @@ -614,15 +614,19 @@ only go to the IOAPIC. On ia64, a IOSAPIC is created.
> 4.25 KVM_IRQ_LINE
So this IOCTL is now used for injecting from a userspace GIC model to
the VCPUs, right? Then this version is OK as userspace should be able to
detect IRQ coalescing per IRQ generating device.
However, injecting into an in-kernel GIC should use KVM_IRQ_LINE_STATUS
later on, keeping the door open for userspace implementing the IRQ
de-coalescing (for custom periodic timer devices). Have you thought
about how that IRQ injecting interface will look like, how the
interrupts will be specified? Do you actually plan to have both version
as ABI (with and without in-kernel irqchip)?
>
> 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
^^^^
Please be more specific to help the poor users of this interface
guessing if the should or should not call CREATE_IRQCHIP first.
> +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 uses two types of interrupt lines per CPU: IRQ and FIQ. The value of the
> +irq field should be (vcpu_index << 1) for IRQs and ((vcpu_index << 1) | 1) for
> +FIQs. Level is used to raise/lower the line.
>
> struct kvm_irq_level {
> union {
> diff --git a/arch/arm/include/asm/kvm.h b/arch/arm/include/asm/kvm.h
> index bc5d72b..4a3e25d 100644
> --- a/arch/arm/include/asm/kvm.h
> +++ b/arch/arm/include/asm/kvm.h
> @@ -22,6 +22,15 @@
> #include <asm/types.h>
>
> #define __KVM_HAVE_GUEST_DEBUG
> +#define __KVM_HAVE_IRQ_LINE
> +
> +/*
> + * KVM_IRQ_LINE macros to set/read IRQ/FIQ for specific VCPU index.
> + */
> +enum KVM_ARM_IRQ_LINE_TYPE {
> + KVM_ARM_IRQ_LINE = 0,
> + KVM_ARM_FIQ_LINE = 1,
> +};
>
> /*
> * Modes used for short-hand mode determinition in the world-switch code and
> diff --git a/arch/arm/include/asm/kvm_arm.h b/arch/arm/include/asm/kvm_arm.h
> index 6e46541..0f641c1 100644
> --- a/arch/arm/include/asm/kvm_arm.h
> +++ b/arch/arm/include/asm/kvm_arm.h
> @@ -74,6 +74,7 @@
> #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/kvm/arm.c b/arch/arm/kvm/arm.c
> index 3f97e7c..8306587 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
> @@ -265,6 +266,7 @@ 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)
> @@ -305,6 +307,51 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
> return -EINVAL;
> }
>
> +int kvm_vm_ioctl_irq_line(struct kvm *kvm, struct kvm_irq_level *irq_level)
> +{
> + unsigned int vcpu_idx;
> + struct kvm_vcpu *vcpu;
> + unsigned long *ptr;
> + bool set;
> + int bit_index;
> +
> + vcpu_idx = irq_level->irq >> 1;
> + if (vcpu_idx >= KVM_MAX_VCPUS)
> + return -EINVAL;
> +
> + vcpu = kvm_get_vcpu(kvm, vcpu_idx);
> + if (!vcpu)
> + return -EINVAL;
> +
> + trace_kvm_set_irq(irq_level->irq, irq_level->level, 0);
> +
> + if ((irq_level->irq & 1) == KVM_ARM_IRQ_LINE)
> + bit_index = ffs(HCR_VI) - 1;
> + else /* KVM_ARM_FIQ_LINE */
> + bit_index = ffs(HCR_VF) - 1;
> +
> + ptr = (unsigned long *)&vcpu->arch.irq_lines;
> + if (irq_level->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 == !!irq_level->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;
> +}
> +
> long kvm_arch_vcpu_ioctl(struct file *filp,
> unsigned int ioctl, unsigned long arg)
> {
> diff --git a/include/linux/kvm.h b/include/linux/kvm.h
> index 5fb08b5..c9b2556 100644
> --- a/include/linux/kvm.h
> +++ b/include/linux/kvm.h
> @@ -111,6 +111,7 @@ 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: IRQ: irq = (2*vcpu_index). FIQ: irq = (2*vcpu_indx + 1).
> */
> union {
> __u32 irq;
>
> --
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>
Jan
--
Siemens AG, Corporate Technology, CT RTC ITP SDP-DE
Corporate Competence Center Embedded Linux
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