[PATCH 14/16] RFC: xen: arm: allow platform code to select dom0 event channel irq

[Ian Campbell <ian.campbell@citrix.com>]

Currently the hardcoded use of GUEST_EVTCHN_PPI is problematic if that is a
real PPI on the platform.

We really need to be smarter about selecting an unused PPI but in the meantime
we can at least give the platform code the option of hardcoding a number which
works for the platform.

Hardcode a suitable PPI on the Xgene platform.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
---
RFC: I'm not all that happy with this, but it seems better than nothing for
4.4...

If other existing platforms also have this issue I can extend the patch if
told what a suitable PPI is.
---
 xen/arch/arm/domain.c                |    7 +++++--
 xen/arch/arm/platform.c              |    7 +++++++
 xen/arch/arm/platforms/xgene-storm.c |    1 +
 xen/include/asm-arm/platform.h       |    5 +++++
 4 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
index 2f57d01..52d2403 100644
--- a/xen/arch/arm/domain.c
+++ b/xen/arch/arm/domain.c
@@ -31,6 +31,7 @@
 #include <asm/processor-ca15.h>
 
 #include <asm/gic.h>
+#include <asm/platform.h>
 #include "vtimer.h"
 #include "vuart.h"
 
@@ -526,8 +527,10 @@ int arch_domain_create(struct domain *d, unsigned int domcr_flags)
     if ( (rc = vcpu_domain_init(d)) != 0 )
         goto fail;
 
-    /* XXX dom0 needs more intelligent selection of PPI */
-    d->arch.evtchn_irq = GUEST_EVTCHN_PPI;
+    if ( d->domain_id )
+        d->arch.evtchn_irq = GUEST_EVTCHN_PPI;
+    else
+        d->arch.evtchn_irq = platform_dom0_evtchn_ppi();
 
     /*
      * Virtual UART is only used by linux early printk and decompress code.
diff --git a/xen/arch/arm/platform.c b/xen/arch/arm/platform.c
index 0fbbdc7..a7f9ee4 100644
--- a/xen/arch/arm/platform.c
+++ b/xen/arch/arm/platform.c
@@ -156,6 +156,13 @@ bool_t platform_device_is_blacklisted(const struct dt_device_node *node)
     return dt_match_node(blacklist, node);
 }
 
+unsigned int platform_dom0_evtchn_ppi(void)
+{
+    if ( platform && platform->dom0_evtchn_ppi )
+        return platform->dom0_evtchn_ppi;
+    return GUEST_EVTCHN_PPI;
+}
+
 /*
  * Local variables:
  * mode: C
diff --git a/xen/arch/arm/platforms/xgene-storm.c b/xen/arch/arm/platforms/xgene-storm.c
index 23986a9..b1b850b 100644
--- a/xen/arch/arm/platforms/xgene-storm.c
+++ b/xen/arch/arm/platforms/xgene-storm.c
@@ -52,6 +52,7 @@ PLATFORM_START(xgene_storm, "APM X-GENE STORM")
     .init = xgene_storm_init,
     .reset = xgene_storm_reset,
     .quirks = xgene_storm_quirks,
+    .dom0_evtchn_ppi = 24,
 PLATFORM_END
 
 /*
diff --git a/xen/include/asm-arm/platform.h b/xen/include/asm-arm/platform.h
index c282b30..92b954d 100644
--- a/xen/include/asm-arm/platform.h
+++ b/xen/include/asm-arm/platform.h
@@ -37,6 +37,10 @@ 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;
 };
 
 /*
@@ -56,6 +60,7 @@ void platform_reset(void);
 void platform_poweroff(void);
 bool_t platform_has_quirk(uint32_t quirk);
 bool_t platform_device_is_blacklisted(const struct dt_device_node *node);
+unsigned int platform_dom0_evtchn_ppi(void);
 
 #define PLATFORM_START(_name, _namestr)                         \
 static const struct platform_desc  __plat_desc_##_name __used   \
-- 
1.7.10.4