Hi Christoffer,
On 03/04/16 10:15, Christoffer Dall wrote:
> On Sat, Mar 26, 2016 at 02:13:59AM +0000, Andre Przywara wrote:
>> The ARM GICv3 ITS MSI controller requires a device ID to be able to
>> assign the proper interrupt vector. On real hardware, this ID is
>> sampled from the bus. To be able to emulate an ITS controller, extend
>> the KVM MSI interface to let userspace provide such a device ID. For
>> PCI devices, the device ID is simply the 16-bit bus-device-function
>> triplet, which should be easily available to the userland tool.
>>
>> Also there is a new KVM capability which advertises whether the
>> current VM requires a device ID to be set along with the MSI data.
>> This flag is still reported as not available everywhere, later we will
>> enable it when ITS emulation is used.
>>
>> Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
>> Reviewed-by: Eric Auger <eric.auger@xxxxxxxxxx>
>> ---
>> Documentation/virtual/kvm/api.txt | 12 ++++++++++--
>> include/uapi/linux/kvm.h | 5 ++++-
>> 2 files changed, 14 insertions(+), 3 deletions(-)
>>
>> diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
>> index cb2ef0b..8f7351d 100644
>> --- a/Documentation/virtual/kvm/api.txt
>> +++ b/Documentation/virtual/kvm/api.txt
>> @@ -2163,10 +2163,18 @@ struct kvm_msi {
>> __u32 address_hi;
>> __u32 data;
>> __u32 flags;
>> - __u8 pad[16];
>> + __u32 devid;
>
> Are we imposing any unfortunate restrictions for other architectures by
> using a u32 over a u64 for the device ID?
Mmmh, good point. I guess not only for other architectures, but also for
the future in general.
Are there any objections against increasing this to a u64?
Cheers,
Andre.
>> + __u8 pad[12];
>> };
>>
>> -No flags are defined so far. The corresponding field must be 0.
>> +flags: KVM_MSI_VALID_DEVID: devid contains a valid value
>> +devid: If KVM_MSI_VALID_DEVID is set, contains a unique device identifier
>> + for the device that wrote the MSI message.
>> + For PCI, this is usually a BFD identifier in the lower 16 bits.
>> +
>> +The per-VM KVM_CAP_MSI_DEVID capability advertises the need to provide
>> +the device ID. If this capability is not set, userland cannot rely on
>> +the kernel to allow the KVM_MSI_VALID_DEVID flag being set.
>>
>>
>> 4.71 KVM_CREATE_PIT2
>> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
>> index 50f44a2..6a02871 100644
>> --- a/include/uapi/linux/kvm.h
>> +++ b/include/uapi/linux/kvm.h
>> @@ -852,6 +852,7 @@ struct kvm_ppc_smmu_info {
>> #define KVM_CAP_S390_RI 124
>> #define KVM_CAP_ARM_PMU_V3 125
>> #define KVM_CAP_VCPU_ATTRIBUTES 126
>> +#define KVM_CAP_MSI_DEVID 127
>>
>> #ifdef KVM_CAP_IRQ_ROUTING
>>
>> @@ -1010,12 +1011,14 @@ struct kvm_one_reg {
>> __u64 addr;
>> };
>>
>> +#define KVM_MSI_VALID_DEVID (1U << 0)
>> struct kvm_msi {
>> __u32 address_lo;
>> __u32 address_hi;
>> __u32 data;
>> __u32 flags;
>> - __u8 pad[16];
>> + __u32 devid;
>> + __u8 pad[12];
>> };
>>
>> struct kvm_arm_device_addr {
>> --
>> 2.7.3
>>
>
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