On Thu, Mar 29, 2012 at 09:14:12PM +0200, Jan Kiszka wrote:
> 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@xxxxxxxxxxx>
> ---
>
> Changes in v4:
> - Fix the build by factoring out kvm_send_userspace_msi:
> irqchip_in_kernel is not generically available. But abstracting it
> for all arch is tricky and therefore left to the poor people who have
> to introduce non-x86 irqchip support to this x86-focused corner.
>
> Lesson (probably not) learned: Never underestimate the complexity of
> trivial changes.
>
> Documentation/virtual/kvm/api.txt | 21 +++++++++++++++++++++
> arch/x86/kvm/Kconfig | 1 +
> include/linux/kvm.h | 11 +++++++++++
> include/linux/kvm_host.h | 2 ++
> virt/kvm/Kconfig | 3 +++
> virt/kvm/irq_comm.c | 14 ++++++++++++++
> virt/kvm/kvm_main.c | 14 ++++++++++++++
> 7 files changed, 66 insertions(+), 0 deletions(-)
>
> diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
> index 81ff39f..ed27d1b 100644
> --- a/Documentation/virtual/kvm/api.txt
> +++ b/Documentation/virtual/kvm/api.txt
> @@ -1482,6 +1482,27 @@ See KVM_ASSIGN_DEV_IRQ for the data structure. The target device is specified
> by assigned_dev_id. In the flags field, only KVM_DEV_ASSIGN_MASK_INTX is
> evaluated.
>
> +4.61 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.
> +
> 4.62 KVM_CREATE_SPAPR_TCE
>
> Capability: KVM_CAP_SPAPR_TCE
> diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig
> index 1a7fe86..a28f338 100644
> --- 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 7a9dd4b..225b452 100644
> --- 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 6cf158c..35c69d6 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -774,6 +774,8 @@ 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 f63ccb0..28694f4 100644
> --- 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 9f614b4..a6a0365 100644
> --- 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 a612bc8..5addfa8 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -2063,6 +2063,17 @@ static long kvm_vm_ioctl(struct file *filp,
> 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;
Wait a second, we should validate flags: you say
"this field should be 0" so we should check it.
> + r = kvm_send_userspace_msi(kvm, &msi);
> + break;
> + }
> +#endif
> default:
> r = kvm_arch_vm_ioctl(filp, ioctl, arg);
> if (r == -ENOTTY)
> @@ -2191,6 +2202,9 @@ 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:
> --
> 1.7.3.4
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