Re: [PATCH v2 1/7] KVM: api: introduce KVM_IRQ_ROUTING_EXTENDED_MSI

From: Eric Auger <eric.auger@linaro.org>
To: Andre Przywara <andre.przywara@arm.com>,
	"eric.auger@st.com" <eric.auger@st.com>
Cc: "linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	Marc Zyngier <Marc.Zyngier@arm.com>,
	"christoffer.dall@linaro.org" <christoffer.dall@linaro.org>,
	"kvmarm@lists.cs.columbia.edu" <kvmarm@lists.cs.columbia.edu>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	"p.fedin@samsung.com" <p.fedin@samsung.com>,
	"pbonzini@redhat.com" <pbonzini@redhat.com>
Subject: Re: [PATCH v2 1/7] KVM: api: introduce KVM_IRQ_ROUTING_EXTENDED_MSI
Date: Mon, 13 Jul 2015 11:25:23 +0200	[thread overview]
Message-ID: <55A38403.8080409@linaro.org> (raw)
In-Reply-To: <55A04A72.4010205@arm.com>

Hi Andre,
On 07/11/2015 12:42 AM, Andre Przywara wrote:
> On 09/07/15 09:22, Eric Auger wrote:
>> On ARM, the MSI msg (address and data) comes along with
>> out-of-band device ID information. The device ID encodes the
>> device that writes the MSI msg. Let's convey the device id in
>> kvm_irq_routing_msi and use a new routing entry type to
>> indicate the devid is populated.
>>
>> Signed-off-by: Eric Auger <eric.auger@linaro.org>
> 
> Reviewed-by: Andre Przywara <andre.przywara@arm.com>
> 
> Just some forward looking statement: If this gets based on top of my ITS
> emulation v2 series,
yes this is my intent
 the documentation should state that the new
> KVM_CAP_MSI_DEVID capability tells userland about the need to provide
> the device ID.
I will add this note

Thanks!
Eric
> 
> Cheers,
> Andre.
> 
>>
>> ---
>>
>> v1 -> v2:
>> - devid id passed in kvm_irq_routing_msi instead of in
>>   kvm_irq_routing_entry
>>
>> RFC -> PATCH
>> - remove kvm_irq_routing_extended_msi and use union instead
>> ---
>>  Documentation/virtual/kvm/api.txt | 10 +++++++++-
>>  include/uapi/linux/kvm.h          |  6 +++++-
>>  2 files changed, 14 insertions(+), 2 deletions(-)
>>
>> diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
>> index bea8de7..3d920cd 100644
>> --- a/Documentation/virtual/kvm/api.txt
>> +++ b/Documentation/virtual/kvm/api.txt
>> @@ -1453,6 +1453,7 @@ struct kvm_irq_routing_entry {
>>  #define KVM_IRQ_ROUTING_IRQCHIP 1
>>  #define KVM_IRQ_ROUTING_MSI 2
>>  #define KVM_IRQ_ROUTING_S390_ADAPTER 3
>> +#define KVM_IRQ_ROUTING_EXTENDED_MSI 4
>>  
>>  No flags are specified so far, the corresponding field must be set to zero.
>>  
>> @@ -1465,9 +1466,16 @@ struct kvm_irq_routing_msi {
>>  	__u32 address_lo;
>>  	__u32 address_hi;
>>  	__u32 data;
>> -	__u32 pad;
>> +	union {
>> +		__u32 pad;
>> +		__u32 devid;
>> +	};
>>  };
>>  
>> +for KVM_IRQ_ROUTING_EXTENDED_MSI routing entry type, the kvm_irq_routing_msi
>> +routing entry is used and devid is populated with the device ID that wrote
>> +the MSI message. For PCI, this is usually a BFD identifier in the lower 16 bits.
>> +
>>  struct kvm_irq_routing_s390_adapter {
>>  	__u64 ind_addr;
>>  	__u64 summary_addr;
>> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
>> index 9a261e5..39ec164 100644
>> --- a/include/uapi/linux/kvm.h
>> +++ b/include/uapi/linux/kvm.h
>> @@ -829,7 +829,10 @@ struct kvm_irq_routing_msi {
>>  	__u32 address_lo;
>>  	__u32 address_hi;
>>  	__u32 data;
>> -	__u32 pad;
>> +	union {
>> +		__u32 pad;
>> +		__u32 devid;
>> +	};
>>  };
>>  
>>  struct kvm_irq_routing_s390_adapter {
>> @@ -844,6 +847,7 @@ struct kvm_irq_routing_s390_adapter {
>>  #define KVM_IRQ_ROUTING_IRQCHIP 1
>>  #define KVM_IRQ_ROUTING_MSI 2
>>  #define KVM_IRQ_ROUTING_S390_ADAPTER 3
>> +#define KVM_IRQ_ROUTING_EXTENDED_MSI 4
>>  
>>  struct kvm_irq_routing_entry {
>>  	__u32 gsi;
>>
>