[PATCH 1/3] irqchip/gic-v3-its: Don't free a vPE table shared with another ITS

[Fuad Tabba]

On GICv4.1, its_alloc_tables() copies a sibling's vPE table baser
rather than allocating one, but its_free_tables() frees it like the
rest. A probe failure on the copying ITS then frees pages the enabled
sibling still points GITS_BASER2 at, and the kernel comes up running
on that sibling.

Mark a shared table so its_free_tables() skips it.

Fixes: 5e5168461c22c ("irqchip/gic-v4.1: VPE table (aka GICR_VPROPBASER) allocation")
Signed-off-by: Fuad Tabba <fuad.tabba at linux.dev>
---
 drivers/irqchip/irq-gic-v3-its.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index e9807af235373..58e52095e6ea8 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -87,6 +87,8 @@ struct its_baser {
 	u64		val;
 	u32		order;
 	u32		psz;
+	/* Inherited from a sibling ITS, not freed here */
+	bool		shared;
 };
 
 struct its_device;
@@ -2604,7 +2606,8 @@ static void its_free_tables(struct its_node *its)
 
 	for (i = 0; i < GITS_BASER_NR_REGS; i++) {
 		if (its->tables[i].base) {
-			its_free_pages(its->tables[i].base, its->tables[i].order);
+			if (!its->tables[i].shared)
+				its_free_pages(its->tables[i].base, its->tables[i].order);
 			its->tables[i].base = NULL;
 		}
 	}
@@ -2703,6 +2706,7 @@ static int its_alloc_tables(struct its_node *its)
 				WARN_ON(i != 2);
 				if ((sibling = find_sibling_its(its))) {
 					*baser = sibling->tables[2];
+					baser->shared = true;
 					its_write_baser(its, baser, baser->val);
 					continue;
 				}
-- 
2.39.5