[PATCH v2 07/14] KVM: ARM: Inject IRQs and FIQs from userspace

Christoffer Dall
2012-10-01T09:10:51Z

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
(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_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.

Signed-off-by: Christoffer Dall <c.dall@virtualopensystems.com>
---
Documentation/virtual/kvm/api.txt | 25 +++++++++++--
arch/arm/include/asm/kvm.h | 21 +++++++++++
arch/arm/include/asm/kvm_arm.h | 1 +
arch/arm/kvm/arm.c | 70 +++++++++++++++++++++++++++++++++++++
arch/arm/kvm/trace.h | 25 +++++++++++++
include/linux/kvm.h | 1 +
6 files changed, 139 insertions(+), 4 deletions(-)

diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index 599b1e7..fd1c1bc 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.h b/arch/arm/include/asm/kvm.h
index 5918afe..eb5f528 100644
--- a/arch/arm/include/asm/kvm.h
+++ b/arch/arm/include/asm/kvm.h
@@ -22,6 +22,7 @@
#include <asm/types.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))
@@ -86,4 +87,24 @@ struct kvm_reg_list {
#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/include/asm/kvm_arm.h b/arch/arm/include/asm/kvm_arm.h
index f6e8f6f..4f54cda 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/kvm/arm.c b/arch/arm/kvm/arm.c
index 5ac3132..15e2ab1 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
@@ -272,6 +273,7 @@ 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)
@@ -312,6 +314,74 @@ 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 ||
+ irq_type == KVM_ARM_IRQ_TYPE_PPI) {
+ if (vcpu_idx >= nrcpus)
+ return -EINVAL;
+
+ vcpu = kvm_get_vcpu(kvm, vcpu_idx);
+ if (!vcpu)
+ return -EINVAL;
+ }
+
+ switch (irq_type) {
+ case KVM_ARM_IRQ_TYPE_CPU:
+ if (irq_num > KVM_ARM_IRQ_CPU_FIQ)
+ return -EINVAL;
+
+ return vcpu_interrupt_line(vcpu, irq_num, level);
+ }
+
+ return -EINVAL;
+}
+
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/linux/kvm.h b/include/linux/kvm.h
index a960f66..8091b1d 100644
--- a/include/linux/kvm.h
+++ b/include/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: IRQ: irq = (2*vcpu_index). FIQ: irq = (2*vcpu_indx + 1).
*/
union {
__u32 irq;