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Commit 07975ad3 authored by Jan Kiszka's avatar Jan Kiszka Committed by Avi Kivity
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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: default avatarJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent 1f15d109

Documentation/virtual/kvm/api.txt

+21 −0
Original line number Diff line number Diff line
@@ -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

arch/x86/kvm/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -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

include/linux/kvm.h

+11 −0
Original line number Diff line number Diff line
@@ -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

include/linux/kvm_host.h

+2 −0
Original line number Diff line number Diff line
@@ -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) {}

virt/kvm/Kconfig

+3 −0
Original line number Diff line number Diff line
@@ -18,3 +18,6 @@ config KVM_MMIO 


config KVM_ASYNC_PF

       bool



config HAVE_KVM_MSI

       bool