[PATCH for-4.22 v2 1/4] xen/arm: gic: defer host LPI allocation until after ITS init

[Mykola Kvach <xakep.amatop@xxxxxxxxx>]

From: Mykola Kvach <mykola_kvach@xxxxxxxx>

gicv3_lpi_init_host_lpis() allocates host LPI state, including the
host LPI lookup table, CPU notifier state and the boot CPU pending table.
Those allocations use gicv3_its_get_memflags().

ITS workarounds are discovered from gicv3_its_init(), so allocating host
LPI state from gicv3_dist_init() can happen before the memory restrictions
required by the ITS are known. On affected systems this can leave
Redistributor LPI state allocated and programmed with the default memory
policy.

Move host LPI initialization after gicv3_its_init(), and only run it when
a host ITS was found. The old call ignored the return value. Now that the
call is made from gicv3_init(), check it and panic on failure because
Redistributor LPI initialization relies on that state being available.

Signed-off-by: Mykola Kvach <mykola_kvach@xxxxxxxx>
---
Changes in v2:
- Replace the v1 ITS pre-initialization hook with the less invasive
  approach suggested during review: move the existing host LPI
  initialization after gicv3_its_init().
- Check gicv3_lpi_init_host_lpis() and panic on failure, matching the fatal
  nature of host LPI setup once ITS initialization succeeded.
---
 xen/arch/arm/gic-v3.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/xen/arch/arm/gic-v3.c b/xen/arch/arm/gic-v3.c
index 17ff85ef5d..acdac22953 100644
--- a/xen/arch/arm/gic-v3.c
+++ b/xen/arch/arm/gic-v3.c
@@ -764,9 +764,6 @@ static void __init gicv3_dist_init(void)
     type = readl_relaxed(GICD + GICD_TYPER);
     nr_lines = 32 * ((type & GICD_TYPE_LINES) + 1);
 
-    if ( type & GICD_TYPE_LPIS )
-        gicv3_lpi_init_host_lpis(GICD_TYPE_ID_BITS(type));
-
     /* Only 1020 interrupts are supported */
     nr_lines = min(1020U, nr_lines);
     gicv3_info.nr_lines = nr_lines;
@@ -1990,6 +1987,17 @@ static int __init gicv3_init(void)
         res = gicv3_its_init();
         if ( res )
             panic("GICv3: ITS: initialization failed: %d\n", res);
+
+        /*
+         * Host LPI allocation uses ITS-derived memory attributes, so defer it
+         * until after gicv3_its_init() has discovered ITS workarounds.
+         */
+        if ( gicv3_its_host_has_its() )
+        {
+            res = gicv3_lpi_init_host_lpis(intid_bits);
+            if ( res )
+                panic("GICv3: LPI initialization failed: %d\n", res);
+        }
     }
 
     res = gicv3_cpu_init();
-- 
2.43.0