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KVM: Introduce direct MSI message injection for in-kernel irqchips

Currently, MSI messages can only be injected to in-kernel irqchips by
defining a corresponding IRQ route for each message. This is not only
unhandy if the MSI messages are generated "on the fly" by user space,
IRQ routes are a limited resource that user space has to manage
carefully.

By providing a direct injection path, we can both avoid using up limited
resources and simplify the necessary steps for user land.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
master
Jan Kiszka 10 years ago
committed by Avi Kivity
parent
commit
07975ad3b3
  1. 21
      Documentation/virtual/kvm/api.txt
  2. 1
      arch/x86/kvm/Kconfig
  3. 11
      include/linux/kvm.h
  4. 2
      include/linux/kvm_host.h
  5. 3
      virt/kvm/Kconfig
  6. 14
      virt/kvm/irq_comm.c
  7. 14
      virt/kvm/kvm_main.c

21
Documentation/virtual/kvm/api.txt

@ -1689,6 +1689,27 @@ where the guest will clear the flag: when the soft lockup watchdog timer resets
itself or when a soft lockup is detected. This ioctl can be called any time
after pausing the vcpu, but before it is resumed.
4.71 KVM_SIGNAL_MSI
Capability: KVM_CAP_SIGNAL_MSI
Architectures: x86
Type: vm ioctl
Parameters: struct kvm_msi (in)
Returns: >0 on delivery, 0 if guest blocked the MSI, and -1 on error
Directly inject a MSI message. Only valid with in-kernel irqchip that handles
MSI messages.
struct kvm_msi {
__u32 address_lo;
__u32 address_hi;
__u32 data;
__u32 flags;
__u8 pad[16];
};
No flags are defined so far. The corresponding field must be 0.
5. The kvm_run structure
Application code obtains a pointer to the kvm_run structure by

1
arch/x86/kvm/Kconfig

@ -36,6 +36,7 @@ config KVM
select TASKSTATS
select TASK_DELAY_ACCT
select PERF_EVENTS
select HAVE_KVM_MSI
---help---
Support hosting fully virtualized guest machines using hardware
virtualization extensions. You will need a fairly recent

11
include/linux/kvm.h

@ -590,6 +590,7 @@ struct kvm_ppc_pvinfo {
#define KVM_CAP_SYNC_REGS 74
#define KVM_CAP_PCI_2_3 75
#define KVM_CAP_KVMCLOCK_CTRL 76
#define KVM_CAP_SIGNAL_MSI 77
#ifdef KVM_CAP_IRQ_ROUTING
@ -715,6 +716,14 @@ struct kvm_one_reg {
__u64 addr;
};
struct kvm_msi {
__u32 address_lo;
__u32 address_hi;
__u32 data;
__u32 flags;
__u8 pad[16];
};
/*
* ioctls for VM fds
*/
@ -789,6 +798,8 @@ struct kvm_s390_ucas_mapping {
/* Available with KVM_CAP_PCI_2_3 */
#define KVM_ASSIGN_SET_INTX_MASK _IOW(KVMIO, 0xa4, \
struct kvm_assigned_pci_dev)
/* Available with KVM_CAP_SIGNAL_MSI */
#define KVM_SIGNAL_MSI _IOW(KVMIO, 0xa5, struct kvm_msi)
/*
* ioctls for vcpu fds

2
include/linux/kvm_host.h

@ -802,6 +802,8 @@ int kvm_set_irq_routing(struct kvm *kvm,
unsigned flags);
void kvm_free_irq_routing(struct kvm *kvm);
int kvm_send_userspace_msi(struct kvm *kvm, struct kvm_msi *msi);
#else
static inline void kvm_free_irq_routing(struct kvm *kvm) {}

3
virt/kvm/Kconfig

@ -18,3 +18,6 @@ config KVM_MMIO
config KVM_ASYNC_PF
bool
config HAVE_KVM_MSI
bool

14
virt/kvm/irq_comm.c

@ -138,6 +138,20 @@ int kvm_set_msi(struct kvm_kernel_irq_routing_entry *e,
return kvm_irq_delivery_to_apic(kvm, NULL, &irq);
}
int kvm_send_userspace_msi(struct kvm *kvm, struct kvm_msi *msi)
{
struct kvm_kernel_irq_routing_entry route;
if (!irqchip_in_kernel(kvm) || msi->flags != 0)
return -EINVAL;
route.msi.address_lo = msi->address_lo;
route.msi.address_hi = msi->address_hi;
route.msi.data = msi->data;
return kvm_set_msi(&route, kvm, KVM_USERSPACE_IRQ_SOURCE_ID, 1);
}
/*
* Return value:
* < 0 Interrupt was ignored (masked or not delivered for other reasons)

14
virt/kvm/kvm_main.c

@ -2059,6 +2059,17 @@ static long kvm_vm_ioctl(struct file *filp,
kvm->bsp_vcpu_id = arg;
mutex_unlock(&kvm->lock);
break;
#endif
#ifdef CONFIG_HAVE_KVM_MSI
case KVM_SIGNAL_MSI: {
struct kvm_msi msi;
r = -EFAULT;
if (copy_from_user(&msi, argp, sizeof msi))
goto out;
r = kvm_send_userspace_msi(kvm, &msi);
break;
}
#endif
default:
r = kvm_arch_vm_ioctl(filp, ioctl, arg);
@ -2188,6 +2199,9 @@ static long kvm_dev_ioctl_check_extension_generic(long arg)
case KVM_CAP_SET_BOOT_CPU_ID:
#endif
case KVM_CAP_INTERNAL_ERROR_DATA:
#ifdef CONFIG_HAVE_KVM_MSI
case KVM_CAP_SIGNAL_MSI:
#endif
return 1;
#ifdef CONFIG_HAVE_KVM_IRQCHIP
case KVM_CAP_IRQ_ROUTING:

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