[PATCH v4 01/12] KVM: extend struct kvm_msi to hold a 32-bit device ID

[Chalamarla, Tirumalesh]

On 3/25/16, 7:13 PM, "kvmarm-bounces at lists.cs.columbia.edu on behalf of Andre Przywara" <kvmarm-bounces at lists.cs.columbia.edu on behalf of andre.przywara at arm.com> 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.

Once VFIO is used it becomes impossible to guess the device ID.
Does the VFIO series take care of this? 
>
>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 at arm.com>
>Reviewed-by: Eric Auger <eric.auger at linaro.org>
>---
> 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;
>+	__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
>
>_______________________________________________
>kvmarm mailing list
>kvmarm at lists.cs.columbia.edu
>https://lists.cs.columbia.edu/mailman/listinfo/kvmarm