[PATCH 02/13] KVM: extend struct kvm_msi to hold a 32-bit device ID

Andre Przywara andre.przywara at arm.com
Fri May 29 02:53:18 PDT 2015

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.

Signed-off-by: Andre Przywara <andre.przywara at arm.com>
 Documentation/virtual/kvm/api.txt | 8 ++++++--
 include/uapi/linux/kvm.h          | 4 +++-
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index 9fa2bf8..891d64a 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -2121,10 +2121,14 @@ 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 is valid, otherwise ignored.
+devid: If KVM_MSI_VALID_DEVID is set, contains a value to identify the device
+       that wrote the MSI message. For PCI, this is usually a BFD
+       identifier in the lower 16 bits.
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 4b60056..2a23705 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -965,12 +965,14 @@ 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 {

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