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>

diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index 81ff39f6248d8bccca9b9c13e85ecb0aae52e3e3..a1552210b16d9d6299b9a213d2f68f4fe7c56f22 100644 (file)
--- a/Documentation/virtual/kvm/api.txt
+++ b/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

diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig
index 1a7fe868f375cb6bccb281599359b8c2dbad8073..a28f338843eaa083a046ea69dca78f6e3ff541fe 100644 (file)
--- a/arch/x86/kvm/Kconfig
+++ b/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

diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index 7a9dd4b3dede496d4a84b686f715406c554fde03..225b452e1d1ddb3e31713663b112791881f2a692 100644 (file)
--- a/include/linux/kvm.h
+++ b/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

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 186ffab0b9f0d46ce9d1da15a387bfd6846d1f9e..6f343307d72b05216aee152ca68f46ecd007132b 100644 (file)
--- a/include/linux/kvm_host.h
+++ b/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) {}

diff --git a/virt/kvm/Kconfig b/virt/kvm/Kconfig
index f63ccb0a5982d15436420a964aa2428ef311f58c..28694f4a91398998f569c234c7faee104a945259 100644 (file)
--- a/virt/kvm/Kconfig
+++ b/virt/kvm/Kconfig
@@ -18,3 +18,6 @@ config KVM_MMIO
 
 config KVM_ASYNC_PF
        bool
+
+config HAVE_KVM_MSI
+       bool

diff --git a/virt/kvm/irq_comm.c b/virt/kvm/irq_comm.c
index 9f614b4e365f77e38ce4b8dec4eeac15148cd5b7..a6a0365475edafc1935e46c04297931eadb8663c 100644 (file)
--- a/virt/kvm/irq_comm.c
+++ b/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)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 9eb7936e491d20d28477660966540ed945fe78a1..1847c762d8d949e320c25c678bcdd652a71b8145 100644 (file)
--- a/virt/kvm/kvm_main.c
+++ b/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: