[Xen-devel] [PATCH v3 04/13] xen: arm: add a quirk to handle platforms with unusual GIC layout

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

On some platforms the pages are placed at a 64K stride instead of as
contiguous 4K pages.

This is because the ARM64 architecture allows for page sizes of 4/16/64K in
the MMU so a larger stride allow more granular control of mappings. We only
currently support 4K.

Use this quirk on the xgene platform.

This should ideally be fixed by an extension to the device tree bindings as
described in http://www.spinics.net/lists/devicetree/msg10473.html especially
http://www.spinics.net/lists/devicetree/msg10478.html. However for the time
being a platform specific quirk will do.

Note that we always map the GICV to the guest (including dom0) at a 4K stride
length and this is reflected in the DTB passed to the guest.

Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
---
v3: Always map the GICV to the guest as contiguous 4k pages.
v2: This replaces "xen: arm: GICC_DIR register at offset 0x10000 instead of 
0x1000"
---
 xen/arch/arm/gic.c                   |   37 ++++++++++++++++++++++++++++------
 xen/arch/arm/platforms/xgene-storm.c |    2 +-
 xen/include/asm-arm/platform.h       |    5 +++++
 3 files changed, 37 insertions(+), 7 deletions(-)

diff --git a/xen/arch/arm/gic.c b/xen/arch/arm/gic.c
index ab49106..da4685e 100644
--- a/xen/arch/arm/gic.c
+++ b/xen/arch/arm/gic.c
@@ -30,6 +30,7 @@
 #include <xen/device_tree.h>
 #include <asm/p2m.h>
 #include <asm/domain.h>
+#include <asm/platform.h>
 
 #include <asm/gic.h>
 
@@ -444,7 +445,10 @@ void __init gic_init(void)
     BUILD_BUG_ON(FIXMAP_ADDR(FIXMAP_GICC1) !=
                  FIXMAP_ADDR(FIXMAP_GICC2)-PAGE_SIZE);
     set_fixmap(FIXMAP_GICC1, gic.cbase >> PAGE_SHIFT, DEV_SHARED);
-    set_fixmap(FIXMAP_GICC2, (gic.cbase >> PAGE_SHIFT) + 1, DEV_SHARED);
+    if ( platform_has_quirk(PLATFORM_QUIRK_GIC_64K_STRIDE) )
+        set_fixmap(FIXMAP_GICC2, (gic.cbase >> PAGE_SHIFT) + 0x10, DEV_SHARED);
+    else
+        set_fixmap(FIXMAP_GICC2, (gic.cbase >> PAGE_SHIFT) + 0x1, DEV_SHARED);
     set_fixmap(FIXMAP_GICH, gic.hbase >> PAGE_SHIFT, DEV_SHARED);
 
     /* Global settings: interrupt distributor */
@@ -823,6 +827,8 @@ void gic_interrupt(struct cpu_user_regs *regs, int is_fiq)
 
 int gicv_setup(struct domain *d)
 {
+    int ret;
+
     /*
      * Domain 0 gets the hardware address.
      * Guests get the virtual platform layout.
@@ -840,11 +846,30 @@ int gicv_setup(struct domain *d)
 
     d->arch.vgic.nr_lines = 0;
 
-    /* map the gic virtual cpu interface in the gic cpu interface region of
-     * the guest */
-    return map_mmio_regions(d, d->arch.vgic.cbase,
-                            d->arch.vgic.cbase + (2 * PAGE_SIZE) - 1,
-                            gic.vbase);
+    /*
+     * Map the gic virtual cpu interface in the gic cpu interface
+     * region of the guest.
+     *
+     * The second page is always mapped at +4K irrespective of the
+     * GIC_64K_STRIDE quirk. The DTB passed to the guest reflects this.
+     */
+    ret = map_mmio_regions(d, d->arch.vgic.cbase,
+                           d->arch.vgic.cbase + PAGE_SIZE - 1,
+                           gic.vbase);
+    if (ret)
+        return ret;
+
+    if ( platform_has_quirk(PLATFORM_QUIRK_GIC_64K_STRIDE) )
+        ret = map_mmio_regions(d, d->arch.vgic.cbase + PAGE_SIZE,
+                               d->arch.vgic.cbase + (2 * PAGE_SIZE) - 1,
+                               gic.vbase + PAGE_SIZE);
+    else
+        ret = map_mmio_regions(d, d->arch.vgic.cbase + PAGE_SIZE,
+                               d->arch.vgic.cbase + (2 * PAGE_SIZE) - 1,
+                               gic.vbase + 16*PAGE_SIZE);
+
+    return ret;
+
 }
 
 static void gic_irq_eoi(void *info)
diff --git a/xen/arch/arm/platforms/xgene-storm.c 
b/xen/arch/arm/platforms/xgene-storm.c
index 0198cec..23ec46d 100644
--- a/xen/arch/arm/platforms/xgene-storm.c
+++ b/xen/arch/arm/platforms/xgene-storm.c
@@ -23,7 +23,7 @@
 
 static uint32_t xgene_storm_quirks(void)
 {
-    return PLATFORM_QUIRK_DOM0_MAPPING_11;
+    return PLATFORM_QUIRK_DOM0_MAPPING_11|PLATFORM_QUIRK_GIC_64K_STRIDE;
 }
 
 
diff --git a/xen/include/asm-arm/platform.h b/xen/include/asm-arm/platform.h
index c282b30..c9314e5 100644
--- a/xen/include/asm-arm/platform.h
+++ b/xen/include/asm-arm/platform.h
@@ -44,6 +44,11 @@ struct platform_desc {
  * Useful on platform where System MMU is not yet implemented
  */
 #define PLATFORM_QUIRK_DOM0_MAPPING_11 (1 << 0)
+/*
+ * Quirk for platforms where the 4K GIC register ranges are placed at
+ * 64K stride.
+ */
+#define PLATFORM_QUIRK_GIC_64K_STRIDE (1 << 1)
 
 void __init platform_init(void);
 int __init platform_init_time(void);
-- 
1.7.10.4


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