[PATCH v3 04/13] irqchip/gic-v3-its: Page-align ITT allocations under protected KVM

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

From: Bartłomiej Grzesik <bgrzesik@google.com>

A later patch has the protected KVM hypervisor take each device's ITT
for as long as the device is mapped, by having the host donate its
pages. A page the hypervisor already owns can't be donated again, so the
MAPD of a device whose ITT shares a page with another device's would be
rejected.

Round each ITT up to whole pages in protected mode. This spends up to a
page per MSI device where a 256-byte ITT would have shared one: tens of
pages on a phone, thousands on a server with thousands of VFs.

Signed-off-by: Bartłomiej Grzesik <bgrzesik@google.com>
Signed-off-by: Fuad Tabba <fuad.tabba@linux.dev>
---
 drivers/irqchip/irq-gic-v3-its.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index 282e4bafb084f..8cc1bd8e7835b 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -3493,6 +3493,9 @@ static struct its_device *its_create_device(struct its_node *its, u32 dev_id,
 	nr_ites = max(2, nvecs);
 	sz = nr_ites * (FIELD_GET(GITS_TYPER_ITT_ENTRY_SIZE, its->typer) + 1);
 	sz = max(sz, ITS_ITT_ALIGN);
+	/* The hypervisor takes ITT pages per device. */
+	if (gic_is_protected_kvm())
+		sz = PAGE_ALIGN(sz);
 
 	itt = itt_alloc_pool(its->numa_node, sz);
 
-- 
2.47.3