[PATCH 1/3] irqchip/gic-v3-its: Align sub-page ITTs to 256 bytes

[Fuad Tabba <fuad.tabba@linux.dev>]

Commit e36d4165f0796 ("irqchip/gic-v3-its: Rely on genpool alignment")
dropped the ALIGN() of the ITT address in MAPD, on the premise that the
ITT pool returns 256-byte aligned blocks. However, the pool's minimum
allocation order is get_order(ITS_ITT_ALIGN), which is 0, so its
granule is a single byte. An ITT whose size is not a multiple of 256
leaves the next one misaligned, MAPD drops the low bits of its address,
and that device's ITEs land on the previous device's ITT. QEMU's
emulated ITS has 12-byte ITEs, so two devices with 32 vectors each are
enough to hit it.

Create the pool with a granule of ITS_ITT_ALIGN.

Fixes: e36d4165f0796 ("irqchip/gic-v3-its: Rely on genpool alignment")
Signed-off-by: Fuad Tabba <fuad.tabba@linux.dev>
---
 drivers/irqchip/irq-gic-v3-its.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index 282e4bafb084f..5613c52adf88e 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -5849,7 +5849,7 @@ int __init its_init(struct fwnode_handle *handle, struct rdists *rdists,
 	bool has_v4_1 = false;
 	int err;
 
-	itt_pool = gen_pool_create(get_order(ITS_ITT_ALIGN), -1);
+	itt_pool = gen_pool_create(ilog2(ITS_ITT_ALIGN), -1);
 	if (!itt_pool)
 		return -ENOMEM;
 
-- 
2.47.3