xen/arm: vgic-v3: Set stride during domain initialization

The stride may not be set if the hardware GIC is using the default
layout. It happens on the Foundation model.

On GICv3, the default stride is 2 * 64K. Therefore it's possible to avoid
checking at every redistributor MMIO access if the stride is not set.

Because domU uses a static stride configuration this only happens for
dom0, so we can move this code in gicv_v3_init. Take the opportunity to move
the stride setting a bit earlier because the loop to set regions will require
the stride.

Also, use 2 * 64K rather than 128K and explain the reason.

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

diff --git a/xen/arch/arm/gic-v3.c b/xen/arch/arm/gic-v3.c
index 47452cac35c536bf5d91ab7db50b3863f55684a1..7b33ff720368b93423652cb8ca19e07e58701494 100644 (file)
--- a/xen/arch/arm/gic-v3.c
+++ b/xen/arch/arm/gic-v3.c
@@ -897,12 +897,21 @@ static int gicv_v3_init(struct domain *d)
     {
         d->arch.vgic.dbase = gicv3.dbase;
         d->arch.vgic.dbase_size = gicv3.dbase_size;
+
+        d->arch.vgic.rdist_stride = gicv3.rdist_stride;
+        /*
+         * If the stride is not set, the default stride for GICv3 is 2 * 64K:
+         *     - first 64k page for Control and Physical LPIs
+         *     - second 64k page for Control and Generation of SGIs
+         */
+        if ( !d->arch.vgic.rdist_stride )
+            d->arch.vgic.rdist_stride = 2 * SZ_64K;
+
         for ( i = 0; i < gicv3.rdist_count; i++ )
         {
             d->arch.vgic.rbase[i] = gicv3.rdist_regions[i].base;
             d->arch.vgic.rbase_size[i] = gicv3.rdist_regions[i].size;
         }
-        d->arch.vgic.rdist_stride = gicv3.rdist_stride;
         d->arch.vgic.rdist_count = gicv3.rdist_count;
     }
     else

diff --git a/xen/arch/arm/vgic-v3.c b/xen/arch/arm/vgic-v3.c
index 2c1471774baa1fdf3dc7e892ec94e3936c8894f8..c5a743a9f4c5eb2a96129050fce015c7363b6345 100644 (file)
--- a/xen/arch/arm/vgic-v3.c
+++ b/xen/arch/arm/vgic-v3.c
@@ -625,11 +625,7 @@ static int vgic_v3_rdistr_mmio_read(struct vcpu *v, mmio_info_t *info)
 
     perfc_incr(vgicr_reads);
 
-    if ( v->domain->arch.vgic.rdist_stride != 0 )
-        offset = info->gpa & (v->domain->arch.vgic.rdist_stride - 1);
-    else
-        /* If stride is not set. Default 128K */
-        offset = info->gpa & (SZ_128K - 1);
+    offset = info->gpa & (v->domain->arch.vgic.rdist_stride - 1);
 
     if ( offset < SZ_64K )
         return __vgic_v3_rdistr_rd_mmio_read(v, info, offset);
@@ -649,11 +645,7 @@ static int vgic_v3_rdistr_mmio_write(struct vcpu *v, mmio_info_t *info)
 
     perfc_incr(vgicr_writes);
 
-    if ( v->domain->arch.vgic.rdist_stride != 0 )
-        offset = info->gpa & (v->domain->arch.vgic.rdist_stride - 1);
-    else
-        /* If stride is not set. Default 128K */
-        offset = info->gpa & (SZ_128K - 1);
+    offset = info->gpa & (v->domain->arch.vgic.rdist_stride - 1);
 
     if ( offset < SZ_64K )
         return __vgic_v3_rdistr_rd_mmio_write(v, info, offset);