[PATCH] xen: arm: remove hardcoded gnttab location from dom0

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

The DT provided to guests (including dom0) includes a Xen node which, among
other things, describes an MMIO region which can be safely used for grant
table mappings (i.e. it is a hole in the physical address space). For domU we
provide a hardcoded values based on our hardcoded guest virtual machine
layout. However for dom0 we need to fit in with the underlying platform.
Leaving this hardcoded was an oversight which on some platforms could result
in the grant table overlaying RAM or MMIO regions which are in use by domain
0.

For the 4.4 release do as we did with the dom0 evtchn PPI and provide a hook
for the platform code to supply a suitable hardcoded address for the platform
(derived from reading the data sheet). Platforms which do not provide the hook
get the existing address as a default.

After 4.4 we should switch to selecting a region of host RAM which is not RAM
in the guest address map. This should be more flexible and safer but the patch
was looking too complex for 4.4.

Platform        Gnttab Address
========        ==============
exynos5.c       0xb0000000, confirmed with Julien.
sunxi.c         0x01d00000, confirmed in data sheet.
midway.c        0xff800000, confirmed with Andre, boot tested.
vexpress.c      0xb0000000, existing hardcoded value was selected for vexpress.
omap5.c         0xb0000000, no datasheet, looks safe in DTB.
xgene-storm.c   0x1f800000, reserved according to datasheet, boot tested.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Cc: Julien.Grall@linaro.org
Cc: Stefano.Stabellini@eu.citrix.com
Cc: Andre Przywara <andre.przywara@linaro.org>
Cc: Chen Baozi <baozich@gmail.com>
Cc: Pranavkumar Sawargaonkar <psawargaonkar@apm.com>
Cc: Anup Patel <apatel@apm.com>
---
 xen/arch/arm/domain_build.c          |    7 +++++--
 xen/arch/arm/platform.c              |   14 ++++++++++++++
 xen/arch/arm/platforms/midway.c      |    3 +++
 xen/arch/arm/platforms/sunxi.c       |    3 +++
 xen/arch/arm/platforms/xgene-storm.c |    3 +++
 xen/include/asm-arm/platform.h       |    7 +++++++
 6 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index be39686..332e937 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -329,6 +329,7 @@ static int make_hypervisor_node(struct domain *d,
     int res;
     int addrcells = dt_n_addr_cells(parent);
     int sizecells = dt_n_size_cells(parent);
+    paddr_t gnttab_start, gnttab_size;
 
     DPRINT("Create hypervisor node\n");
 
@@ -350,10 +351,12 @@ static int make_hypervisor_node(struct domain *d,
     if ( res )
         return res;
 
-    DPRINT("  Grant table range: 0xb0000000-0x20000\n");
+    platform_dom0_gnttab(&gnttab_start, &gnttab_size);
+    DPRINT("  Grant table range: %#"PRIpaddr"-%#"PRIpaddr"\n",
+           gnttab_start, gnttab_start + gnttab_size);
     /* reg 0 is grant table space */
     cells = &reg[0];
-    dt_set_range(&cells, parent, 0xb0000000, 0x20000);
+    dt_set_range(&cells, parent, gnttab_start, gnttab_size);
     res = fdt_property(fdt, "reg", reg,
                        dt_cells_to_size(addrcells + sizecells));
     if ( res )
diff --git a/xen/arch/arm/platform.c b/xen/arch/arm/platform.c
index a7f9ee4..87ceff1 100644
--- a/xen/arch/arm/platform.c
+++ b/xen/arch/arm/platform.c
@@ -163,6 +163,20 @@ unsigned int platform_dom0_evtchn_ppi(void)
     return GUEST_EVTCHN_PPI;
 }
 
+void platform_dom0_gnttab(paddr_t *start, paddr_t *size)
+{
+    if ( platform && platform->dom0_gnttab_size )
+    {
+        *start = platform->dom0_gnttab_start;
+        *size = platform->dom0_gnttab_size;
+    }
+    else
+    {
+        *start = 0xb0000000;
+        *size = 0x20000;
+    }
+}
+
 /*
  * Local variables:
  * mode: C
diff --git a/xen/arch/arm/platforms/midway.c b/xen/arch/arm/platforms/midway.c
index 399056b..27f46f8 100644
--- a/xen/arch/arm/platforms/midway.c
+++ b/xen/arch/arm/platforms/midway.c
@@ -57,6 +57,9 @@ PLATFORM_START(midway, "CALXEDA MIDWAY")
     .compatible = midway_dt_compat,
     .reset = midway_reset,
     .quirks = midway_quirks,
+
+    .dom0_gnttab_start = 0xff800000,
+    .dom0_gnttab_size = 0x20000,
 PLATFORM_END
 
 /*
diff --git a/xen/arch/arm/platforms/sunxi.c b/xen/arch/arm/platforms/sunxi.c
index b466518..fb12801 100644
--- a/xen/arch/arm/platforms/sunxi.c
+++ b/xen/arch/arm/platforms/sunxi.c
@@ -37,6 +37,9 @@ static const struct dt_device_match sunxi_blacklist_dev[] __initconst =
 PLATFORM_START(sunxi, "Allwinner A20")
     .compatible = sunxi_dt_compat,
     .blacklist_dev = sunxi_blacklist_dev,
+
+    .dom0_gnttab_start = 0x01d00000,
+    .dom0_gnttab_size = 0x20000,
 PLATFORM_END
 
 /*
diff --git a/xen/arch/arm/platforms/xgene-storm.c b/xen/arch/arm/platforms/xgene-storm.c
index ea9b0f4..c0c6857 100644
--- a/xen/arch/arm/platforms/xgene-storm.c
+++ b/xen/arch/arm/platforms/xgene-storm.c
@@ -118,7 +118,10 @@ PLATFORM_START(xgene_storm, "APM X-GENE STORM")
     .compatible = xgene_storm_dt_compat,
     .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 5900ee4..bda4e41 100644
--- a/xen/include/asm-arm/platform.h
+++ b/xen/include/asm-arm/platform.h
@@ -41,6 +41,12 @@ struct platform_desc {
      * 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
+     * 0xb0000000-0xb0020000.
+     */
+    paddr_t dom0_gnttab_start, dom0_gnttab_size;
 };
 
 /*
@@ -66,6 +72,7 @@ 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);
+void platform_dom0_gnttab(paddr_t *start, paddr_t *size);
 
 #define PLATFORM_START(_name, _namestr)                         \
 static const struct platform_desc  __plat_desc_##_name __used   \
-- 
1.7.10.4