xen/arm: Automatically find a PPI for the DOM0 event channel interrupt

Use the new vgic interface to know which virtual PPI is free and use it
for the event channel code.

At the DOM0 creation time, Xen doesn't know which vIRQ will be free.
All the vIRQ will be reserved when we parse the device tree. So we can
allocate the vIRQ just after the device tree has been parsed.

It's safe to defer the allocation because no vIRQ can be injected as
long as the vCPU is not online.

As the device tree node "hypervisor" containing the description of the
event channel interrupt is created earlier, add a placeholder which will
be fix up once Xen has allocated the PPI.

Also correct the check in arch_domain_create to use is_hardware_domain.

Signed-off-by: Julien Grall <julien.grall@linaro.org>
Acked-by: Ian Campbell <ian.campbell@citrix.com>

diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
index 7a690b243411c92b73af4fcf03ef5b361aefa297..fdba081a7a68980cc647d5200ef6a7d75679ee52 100644 (file)
--- a/xen/arch/arm/domain.c
+++ b/xen/arch/arm/domain.c
@@ -542,13 +542,18 @@ int arch_domain_create(struct domain *d, unsigned int domcr_flags)
     if ( (rc = domain_vtimer_init(d)) != 0 )
         goto fail;
 
-    if ( d->domain_id )
+    /*
+     * The hardware domain will get a PPI later in
+     * arch/arm/domain_build.c  depending on the
+     * interrupt map of the hardware.
+     */
+    if ( !is_hardware_domain(d) )
+    {
         d->arch.evtchn_irq = GUEST_EVTCHN_PPI;
-    else
-        d->arch.evtchn_irq = platform_dom0_evtchn_ppi();
-
-    if ( !vgic_reserve_virq(d, d->arch.evtchn_irq) )
-        BUG();
+        /* At this stage vgic_reserve_virq should never fail */
+        if ( !vgic_reserve_virq(d, GUEST_EVTCHN_PPI) )
+            BUG();
+    }
 
     /*
      * Virtual UART is only used by linux early printk and decompress code.

diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index 137cd2a6c91613fa5de7546232252bf1fa3a50f2..9f1f59fa1e40d4e437b8fc692750bcbaa5792ba7 100644 (file)
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -627,16 +627,10 @@ static int make_hypervisor_node(struct domain *d,
         return res;
 
     /*
-     * interrupts is evtchn upcall:
-     *  - Active-low level-sensitive
-     *  - All cpus
-     *
-     * TODO: Handle correctly the cpumask
+     * Placeholder for the event channel interrupt.  The values will be
+     * replaced later.
      */
-    DPRINT("  Event channel interrupt to %u\n", d->arch.evtchn_irq);
-    set_interrupt_ppi(intr, d->arch.evtchn_irq, 0xf,
-                   DT_IRQ_TYPE_LEVEL_LOW);
-
+    set_interrupt_ppi(intr, ~0, 0xf, DT_IRQ_TYPE_INVALID);
     res = fdt_property_interrupts(fdt, &intr, 1);
     if ( res )
         return res;
@@ -1277,6 +1271,43 @@ static void initrd_load(struct kernel_info *kinfo)
     }
 }
 
+static void evtchn_fixup(struct domain *d, struct kernel_info *kinfo)
+{
+    int res, node;
+    gic_interrupt_t intr;
+
+    /*
+     * The allocation of the event channel IRQ has been deferred until
+     * now. At this time, all PPIs used by DOM0 have been registered.
+     */
+    res = vgic_allocate_ppi(d);
+    if ( res < 0 )
+        panic("Unable to allocate a PPI for the event channel interrupt\n");
+
+    d->arch.evtchn_irq = res;
+
+    printk("Allocating PPI %u for event channel interrupt\n",
+           d->arch.evtchn_irq);
+
+    /* Fix up "interrupts" in /hypervisor node */
+    node = fdt_path_offset(kinfo->fdt, "/hypervisor");
+    if ( node < 0 )
+        panic("Cannot find the /hypervisor node");
+
+    /* Interrupt event channel upcall:
+     *  - Active-low level-sensitive
+     *  - All CPUs
+     *
+     *  TODO: Handle properly the cpumask
+     */
+    set_interrupt_ppi(intr, d->arch.evtchn_irq, 0xf,
+                      DT_IRQ_TYPE_LEVEL_LOW);
+    res = fdt_setprop_inplace(kinfo->fdt, node, "interrupts",
+                              &intr, sizeof(intr));
+    if ( res )
+        panic("Cannot fix up \"interrupts\" property of the hypervisor node");
+}
+
 int construct_dom0(struct domain *d)
 {
     struct kernel_info kinfo = {};
@@ -1338,6 +1369,8 @@ int construct_dom0(struct domain *d)
     kernel_load(&kinfo);
     /* initrd_load will fix up the fdt, so call it before dtb_load */
     initrd_load(&kinfo);
+    /* Allocate the event channel IRQ and fix up the device tree */
+    evtchn_fixup(d, &kinfo);
     dtb_load(&kinfo);
 
     /* Now that we are done restore the original p2m and current. */

diff --git a/xen/arch/arm/platform.c b/xen/arch/arm/platform.c
index a79a0980799bafdbf93fa6973f9fa45e818ee472..86daf2bf6c55447267b25d36b14c83a9e6e43281 100644 (file)
--- a/xen/arch/arm/platform.c
+++ b/xen/arch/arm/platform.c
@@ -160,13 +160,6 @@ bool_t platform_device_is_blacklisted(const struct dt_device_node *node)
     return (dt_match_node(blacklist, node) != NULL);
 }
 
-unsigned int platform_dom0_evtchn_ppi(void)
-{
-    if ( platform && platform->dom0_evtchn_ppi )
-        return platform->dom0_evtchn_ppi;
-    return GUEST_EVTCHN_PPI;
-}
-
 void platform_dom0_gnttab(paddr_t *start, paddr_t *size)
 {
     if ( platform && platform->dom0_gnttab_size )

diff --git a/xen/arch/arm/platforms/xgene-storm.c b/xen/arch/arm/platforms/xgene-storm.c
index ef3ba63cdc451e00b8718606e5e44a6c3b79e203..eee650e84d171b384d6432cf42e68bac03f94b4c 100644 (file)
--- a/xen/arch/arm/platforms/xgene-storm.c
+++ b/xen/arch/arm/platforms/xgene-storm.c
@@ -232,7 +232,6 @@ PLATFORM_START(xgene_storm, "APM X-GENE STORM")
     .quirks = xgene_storm_quirks,
     .specific_mapping = xgene_storm_specific_mapping,
 
-    .dom0_evtchn_ppi = 24,
     .dom0_gnttab_start = 0x1f800000,
     .dom0_gnttab_size = 0x20000,
 PLATFORM_END

diff --git a/xen/include/asm-arm/platform.h b/xen/include/asm-arm/platform.h
index eefaca6e04f5e0adbeb08ba0980aef96d9617a10..4eba37bf7f71937006b5f3e5e2749a187796e4c8 100644 (file)
--- a/xen/include/asm-arm/platform.h
+++ b/xen/include/asm-arm/platform.h
@@ -37,10 +37,6 @@ struct platform_desc {
      * List of devices which must not pass-through to a guest
      */
     const struct dt_device_match *blacklist_dev;
-    /*
-     * The IRQ (PPI) to use to inject event channels to dom0.
-     */
-    unsigned int dom0_evtchn_ppi;
     /*
      * The location of a region of physical address space which dom0
      * can use for grant table mappings. If size is zero defaults to