[RFC PATCH] xen/dm: arm: Introudce arm_inject_msi DM op

[Mykyta Poturai <Mykyta_Poturai@xxxxxxxx>]

This patch adds the ability for the device emulator to inject MSI
interrupts into guests. This is done by adding a new DM op to the device
model library.

It is not possible to reuse already existing inject_msi DM op, because
it does not have a devid parameter, which is required for translation of
MSIs to interrupt numbers on ARM.

This approach was successfully tested on a virtio-pci setup with QEMU
backend emulating block devices with following changes from the mainline
Xen:

This branch was taken as a base for virtio-pci:
https://github.com/xen-troops/xen/tree/xen-4.18-xt0.2

With added new VGICv3 from here:
https://github.com/Deedone/xen/tree/new_vgic_v2
(although it should also work with the current VGIC)

And patches from this branch to allow for proper ITS emulation in guests:
https://github.com/stewdk/xen/commits/pcie-passthrough-arm-vpci-v11

The main purpose of this RFC is to get some feedback on the addition of
the new DM op. Is it the right approach or should we somehow modify the
existing inject_msi DM op to be compatible with ARM?

Signed-off-by: Mykyta Poturai <mykyta_poturai@xxxxxxxx>
---
 tools/include/xendevicemodel.h               |  4 ++++
 tools/libs/devicemodel/core.c                | 19 +++++++++++++++++++
 tools/libs/devicemodel/libxendevicemodel.map |  5 +++++
 xen/arch/arm/dm.c                            | 15 +++++++++++++++
 xen/arch/arm/include/asm/new_vgic.h          |  2 ++
 xen/arch/arm/vgic/vgic-its.c                 |  2 +-
 xen/include/public/hvm/dm_op.h               | 10 ++++++++++
 7 files changed, 56 insertions(+), 1 deletion(-)

diff --git a/tools/include/xendevicemodel.h b/tools/include/xendevicemodel.h
index 797e0c6b29..e28710a6a5 100644
--- a/tools/include/xendevicemodel.h
+++ b/tools/include/xendevicemodel.h
@@ -236,6 +236,10 @@ int xendevicemodel_inject_msi(
     xendevicemodel_handle *dmod, domid_t domid, uint64_t msi_addr,
     uint32_t msi_data);
 
+int xendevicemodel_arm_inject_msi(
+    xendevicemodel_handle *dmod, domid_t domid, uint64_t msi_addr, uint32_t 
devid,
+    uint32_t data);
+
 /**
  * This function enables tracking of changes in the VRAM area.
  *
diff --git a/tools/libs/devicemodel/core.c b/tools/libs/devicemodel/core.c
index 8e619eeb0a..d15ffa46fb 100644
--- a/tools/libs/devicemodel/core.c
+++ b/tools/libs/devicemodel/core.c
@@ -448,6 +448,25 @@ int xendevicemodel_set_irq_level(
     return xendevicemodel_op(dmod, domid, 1, &op, sizeof(op));
 }
 
+int xendevicemodel_arm_inject_msi(
+    xendevicemodel_handle *dmod, domid_t domid, uint64_t msi_addr, uint32_t 
msi_data,
+    uint32_t devid)
+{
+    struct xen_dm_op op;
+    struct xen_dm_op_arm_inject_msi *data;
+
+    memset(&op, 0, sizeof(op));
+
+    op.op = XEN_DMOP_arm_inject_msi;
+    data = &op.u.arm_inject_msi;
+
+    data->addr = msi_addr;
+    data->devid = devid;
+    data->data = msi_data;
+
+    return xendevicemodel_op(dmod, domid, 1, &op, sizeof(op));
+}
+
 int xendevicemodel_set_pci_link_route(
     xendevicemodel_handle *dmod, domid_t domid, uint8_t link, uint8_t irq)
 {
diff --git a/tools/libs/devicemodel/libxendevicemodel.map 
b/tools/libs/devicemodel/libxendevicemodel.map
index f7f9e3d932..8dceba5056 100644
--- a/tools/libs/devicemodel/libxendevicemodel.map
+++ b/tools/libs/devicemodel/libxendevicemodel.map
@@ -44,3 +44,8 @@ VERS_1.4 {
                xendevicemodel_set_irq_level;
                xendevicemodel_nr_vcpus;
 } VERS_1.3;
+
+VERS_1.5 {
+       global:
+               xendevicemodel_arm_inject_msi;
+} VERS_1.4;
diff --git a/xen/arch/arm/dm.c b/xen/arch/arm/dm.c
index 5569efa121..b42f11e569 100644
--- a/xen/arch/arm/dm.c
+++ b/xen/arch/arm/dm.c
@@ -27,6 +27,7 @@ int dm_op(const struct dmop_args *op_args)
         [XEN_DMOP_set_ioreq_server_state]           = sizeof(struct 
xen_dm_op_set_ioreq_server_state),
         [XEN_DMOP_destroy_ioreq_server]             = sizeof(struct 
xen_dm_op_destroy_ioreq_server),
         [XEN_DMOP_set_irq_level]                    = sizeof(struct 
xen_dm_op_set_irq_level),
+        [XEN_DMOP_arm_inject_msi]                   = sizeof(struct 
xen_dm_op_arm_inject_msi),
         [XEN_DMOP_nr_vcpus]                         = sizeof(struct 
xen_dm_op_nr_vcpus),
     };
 
@@ -112,6 +113,20 @@ int dm_op(const struct dmop_args *op_args)
         break;
     }
 
+    case XEN_DMOP_arm_inject_msi:
+    {
+        const struct xen_dm_op_arm_inject_msi *data =
+            &op.u.arm_inject_msi;
+
+        if ( d->arch.vgic.its == NULL )
+        {
+            rc = -EINVAL;
+            break;
+        }
+        vgic_its_trigger_msi(d, d->arch.vgic.its, data->devid, data->data);
+        break;
+
+    }
     case XEN_DMOP_nr_vcpus:
     {
         struct xen_dm_op_nr_vcpus *data = &op.u.nr_vcpus;
diff --git a/xen/arch/arm/include/asm/new_vgic.h 
b/xen/arch/arm/include/asm/new_vgic.h
index dfc434ab41..dedc294ce9 100644
--- a/xen/arch/arm/include/asm/new_vgic.h
+++ b/xen/arch/arm/include/asm/new_vgic.h
@@ -275,6 +275,8 @@ int vgic_its_add_device(struct domain *d, struct 
vgic_its_device *its_dev);
 void vgic_its_delete_device(struct domain *d, struct vgic_its_device *its_dev);
 struct vgic_its_device* vgic_its_get_device(struct domain *d, paddr_t 
vdoorbell,
                                          uint32_t vdevid);
+int vgic_its_trigger_msi(struct domain *d, struct vgic_its *its,
+                                u32 devid, u32 eventid);
 #else
 static inline void vgic_enable_lpis(struct vcpu *vcpu)
 {
diff --git a/xen/arch/arm/vgic/vgic-its.c b/xen/arch/arm/vgic/vgic-its.c
index fd5aaf4a70..706987d93a 100644
--- a/xen/arch/arm/vgic/vgic-its.c
+++ b/xen/arch/arm/vgic/vgic-its.c
@@ -608,7 +608,7 @@ int vgic_its_inject_cached_translation(struct domain *d, 
struct vgic_its *its, u
  * Returns 0 on success, a positive error value for any ITS mapping
  * related errors and negative error values for generic errors.
  */
-static int vgic_its_trigger_msi(struct domain *d, struct vgic_its *its,
+int vgic_its_trigger_msi(struct domain *d, struct vgic_its *its,
                                 u32 devid, u32 eventid)
 {
     struct vgic_irq *irq = NULL;
diff --git a/xen/include/public/hvm/dm_op.h b/xen/include/public/hvm/dm_op.h
index fa98551914..a7d72e4389 100644
--- a/xen/include/public/hvm/dm_op.h
+++ b/xen/include/public/hvm/dm_op.h
@@ -444,6 +444,15 @@ struct xen_dm_op_nr_vcpus {
 };
 typedef struct xen_dm_op_nr_vcpus xen_dm_op_nr_vcpus_t;
 
+#define XEN_DMOP_arm_inject_msi 21
+
+struct xen_dm_op_arm_inject_msi {
+    uint64_t addr;
+    uint32_t data;
+    uint32_t devid;
+};
+typedef struct xen_dm_op_arm_inject_msi xen_dm_op_arm_inject_msi_t;
+
 struct xen_dm_op {
     uint32_t op;
     uint32_t pad;
@@ -463,6 +472,7 @@ struct xen_dm_op {
         xen_dm_op_set_mem_type_t set_mem_type;
         xen_dm_op_inject_event_t inject_event;
         xen_dm_op_inject_msi_t inject_msi;
+        xen_dm_op_arm_inject_msi_t arm_inject_msi;
         xen_dm_op_map_mem_type_to_ioreq_server_t map_mem_type_to_ioreq_server;
         xen_dm_op_remote_shutdown_t remote_shutdown;
         xen_dm_op_relocate_memory_t relocate_memory;
-- 
2.34.1