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    SubjectRE: [PATCH 1/7] KVM: api: add kvm_irq_routing_extended_msi
    Date
     Hello!

    > -----Original Message-----
    > From: kvm-owner@vger.kernel.org [mailto:kvm-owner@vger.kernel.org] On Behalf Of Eric Auger
    > Sent: Monday, June 29, 2015 6:37 PM
    > To: eric.auger@st.com; eric.auger@linaro.org; linux-arm-kernel@lists.infradead.org;
    > marc.zyngier@arm.com; christoffer.dall@linaro.org; andre.przywara@arm.com;
    > kvmarm@lists.cs.columbia.edu; kvm@vger.kernel.org
    > Cc: linux-kernel@vger.kernel.org; patches@linaro.org; p.fedin@samsung.com; pbonzini@redhat.com
    > Subject: [PATCH 1/7] KVM: api: add kvm_irq_routing_extended_msi
    >
    > On ARM, the MSI msg (address and data) comes along with
    > out-of-band device ID information. The device ID encodes the device
    > that composes the MSI msg. Let's create a new routing entry type,
    > dubbed KVM_IRQ_ROUTING_EXTENDED_MSI and use the __u32 pad space
    > to convey the device ID.
    >
    > Signed-off-by: Eric Auger <eric.auger@linaro.org>
    >
    > ---
    >
    > RFC -> PATCH
    > - remove kvm_irq_routing_extended_msi and use union instead
    > ---
    > Documentation/virtual/kvm/api.txt | 9 ++++++++-
    > include/uapi/linux/kvm.h | 6 +++++-
    > 2 files changed, 13 insertions(+), 2 deletions(-)
    >
    > diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
    > index d20fd94..6426ae9 100644
    > --- a/Documentation/virtual/kvm/api.txt
    > +++ b/Documentation/virtual/kvm/api.txt
    > @@ -1414,7 +1414,10 @@ struct kvm_irq_routing_entry {
    > __u32 gsi;
    > __u32 type;
    > __u32 flags;
    > - __u32 pad;
    > + union {
    > + __u32 pad;
    > + __u32 devid;
    > + };
    > union {
    > struct kvm_irq_routing_irqchip irqchip;
    > struct kvm_irq_routing_msi msi;

    devid is actually a part of MSI bunch. Shouldn't it be a part of struct kvm_irq_routing_msi then?
    It also has reserved pad.

    > @@ -1427,6 +1430,10 @@ 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
    > +
    > +In case of KVM_IRQ_ROUTING_EXTENDED_MSI routing type, devid is used to convey
    > +the device ID.
    >
    > No flags are specified so far, the corresponding field must be set to zero.

    What if we use KVM_MSI_VALID_DEVID flag instead of new KVM_IRQ_ROUTING_EXTENDED_MSI definition? I
    believe this would make an API more consistent and introduce less new definitions.

    >
    > diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
    > index 2a23705..8484681 100644
    > --- a/include/uapi/linux/kvm.h
    > +++ b/include/uapi/linux/kvm.h
    > @@ -841,12 +841,16 @@ 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;
    > __u32 type;
    > __u32 flags;
    > - __u32 pad;
    > + union {
    > + __u32 pad;
    > + __u32 devid;
    > + };
    > union {
    > struct kvm_irq_routing_irqchip irqchip;
    > struct kvm_irq_routing_msi msi;
    > --
    > 1.9.1
    >
    > --
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    Kind regards,
    Pavel Fedin
    Expert Engineer
    Samsung Electronics Research center Russia



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