On 2012-03-29 21:41, Michael S. Tsirkin wrote:
> 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.
Yep, see kvm_send_userspace_msi.
Jan
>
>> + 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
--
Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux
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