[Xen-devel] [PATCH v3 13/24] xen/arm: Implement hypercall PHYSDEVOP_{, un}map_pirq

[Julien Grall <julien.grall@xxxxxxxxxx>]

The physdev sub-hypercalls PHYSDEVOP_{,map}_pirq allow the toolstack to
assign/deassign a physical IRQ to the guest (via the config options "irqs"
for xl). The x86 version is using them with PIRQ (IRQ bound to an event
channel). As ARM doesn't have a such concept, we could reuse it to bound
a physical IRQ to a virtual IRQ.

For now, we allow only SPIs to be mapped to the guest.
The type MAP_PIRQ_TYPE_GSI is used for this purpose.

Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxx>

---
    I'm not sure it's the best solution to reuse hypercalls for a
    different purpose. If x86 plan to have a such concept (i.e binding a
    physical IRQ to a virtual IRQ), we could introduce new hypercalls.
    Any thoughs?

    TODO: This patch is lacking of support of vIRQ != IRQ. I plan to
    handle it correctly on the next version.

    Changes in v3:
        - Functions to allocate/release/reserved a VIRQ has been moved
        in a separate patch
        - Make clear that only MAP_PIRQ_GSI is only supported for now

    Changes in v2:
        - Add PHYSDEVOP_unmap_pirq
        - Rework commit message
        - Add functions to allocate/release a VIRQ
        - is_routable_irq has been renamed into is_assignable_irq
---
 xen/arch/arm/physdev.c | 136 ++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 134 insertions(+), 2 deletions(-)

diff --git a/xen/arch/arm/physdev.c b/xen/arch/arm/physdev.c
index 61b4a18..0cf9bbd 100644
--- a/xen/arch/arm/physdev.c
+++ b/xen/arch/arm/physdev.c
@@ -8,13 +8,145 @@
 #include <xen/types.h>
 #include <xen/lib.h>
 #include <xen/errno.h>
+#include <xen/iocap.h>
+#include <xen/guest_access.h>
+#include <xsm/xsm.h>
+#include <asm/current.h>
 #include <asm/hypercall.h>
+#include <public/physdev.h>
 
+static int physdev_map_pirq(domid_t domid, int type, int index, int *pirq_p)
+{
+    struct domain *d;
+    int ret;
+    int irq = index;
+    int virq;
+
+    d = rcu_lock_domain_by_any_id(domid);
+    if ( d == NULL )
+        return -ESRCH;
+
+    ret = xsm_map_domain_pirq(XSM_TARGET, d);
+    if ( ret )
+        goto free_domain;
+
+    /* For now we only suport GSI */
+    if ( type != MAP_PIRQ_TYPE_GSI )
+    {
+        ret = -EINVAL;
+        dprintk(XENLOG_G_ERR,
+                "dom%u: wrong map_pirq type 0x%x, only MAP_PIRQ_TYPE_GSI is 
supported.\n",
+                d->domain_id, type);
+        goto free_domain;
+    }
+
+    if ( !is_assignable_irq(irq) )
+    {
+        ret = -EINVAL;
+        dprintk(XENLOG_G_ERR, "IRQ%u is not routable to a guest\n", irq);
+        goto free_domain;
+    }
+
+    ret = -EPERM;
+    if ( !irq_access_permitted(current->domain, irq) )
+        goto free_domain;
+
+    if ( *pirq_p < 0 )
+    {
+        BUG_ON(irq < 16);   /* is_assignable_irq already denies SGIs */
+        virq = vgic_allocate_virq(d, (irq >= 32));
+
+        ret = -ENOSPC;
+        if ( virq < 0 )
+            goto free_domain;
+    }
+    else
+    {
+        ret = -EBUSY;
+        virq = *pirq_p;
+
+        if ( !vgic_reserve_virq(d, virq) )
+            goto free_domain;
+    }
+
+    gdprintk(XENLOG_DEBUG, "irq = %u virq = %u\n", irq, virq);
+
+    ret = route_irq_to_guest(d, virq, irq, "routed IRQ");
+
+    if ( !ret )
+        *pirq_p = virq;
+    else
+        vgic_free_virq(d, virq);
+
+free_domain:
+    rcu_unlock_domain(d);
+
+    return ret;
+}
+
+int physdev_unmap_pirq(domid_t domid, int pirq)
+{
+    struct domain *d;
+    int ret;
+
+    d = rcu_lock_domain_by_any_id(domid);
+    if ( d == NULL )
+        return -ESRCH;
+
+    ret = xsm_unmap_domain_pirq(XSM_TARGET, d);
+    if ( ret )
+        goto free_domain;
+
+    ret = release_guest_irq(d, pirq);
+    if ( ret )
+        goto free_domain;
+
+    vgic_free_virq(d, pirq);
+
+free_domain:
+    rcu_unlock_domain(d);
+
+    return ret;
+}
 
 int do_physdev_op(int cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
 {
-    printk("%s %d cmd=%d: not implemented yet\n", __func__, __LINE__, cmd);
-    return -ENOSYS;
+    int ret;
+
+    switch ( cmd )
+    {
+    case PHYSDEVOP_map_pirq:
+        {
+            physdev_map_pirq_t map;
+
+            ret = -EFAULT;
+            if ( copy_from_guest(&map, arg, 1) != 0 )
+                break;
+
+            ret = physdev_map_pirq(map.domid, map.type, map.index, &map.pirq);
+
+            if ( __copy_to_guest(arg, &map, 1) )
+                ret = -EFAULT;
+        }
+        break;
+
+    case PHYSDEVOP_unmap_pirq:
+        {
+            physdev_unmap_pirq_t unmap;
+
+            ret = -EFAULT;
+            if ( copy_from_guest(&unmap, arg, 1) != 0 )
+                break;
+
+            ret = physdev_unmap_pirq(unmap.domid, unmap.pirq);
+        }
+
+    default:
+        ret = -ENOSYS;
+        break;
+    }
+
+    return ret;
 }
 
 /*
-- 
2.1.4


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