[PATCH AUTOSEL 6.6 198/294] firmware: arm_ffa: Reject higher major version as incompatible

[Sasha Levin]

From: Sudeep Holla <sudeep.holla at arm.com>

[ Upstream commit efff6a7f16b34fd902f342b58bd8bafc2d6f2fd1 ]

When the firmware compatibility was handled previously in the commit
8e3f9da608f1 ("firmware: arm_ffa: Handle compatibility with different firmware versions"),
we only addressed firmware versions that have higher minor versions
compared to the driver version which is should be considered compatible
unless the firmware returns NOT_SUPPORTED.

However, if the firmware reports higher major version than the driver
supported, we need to reject it. If the firmware can work in a compatible
mode with the driver requested version, it must return the same major
version as requested.

Tested-by: Viresh Kumar <viresh.kumar at linaro.org>
Message-Id: <20250217-ffa_updates-v3-12-bd1d9de615e7 at arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla at arm.com>
Signed-off-by: Sasha Levin <sashal at kernel.org>
---
 drivers/firmware/arm_ffa/driver.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/firmware/arm_ffa/driver.c b/drivers/firmware/arm_ffa/driver.c
index 7cd6b1564e801..906f0988bb557 100644
--- a/drivers/firmware/arm_ffa/driver.c
+++ b/drivers/firmware/arm_ffa/driver.c
@@ -121,6 +121,14 @@ static int ffa_version_check(u32 *version)
 		return -EOPNOTSUPP;
 	}
 
+	if (FFA_MAJOR_VERSION(ver.a0) > FFA_MAJOR_VERSION(FFA_DRIVER_VERSION)) {
+		pr_err("Incompatible v%d.%d! Latest supported v%d.%d\n",
+		       FFA_MAJOR_VERSION(ver.a0), FFA_MINOR_VERSION(ver.a0),
+		       FFA_MAJOR_VERSION(FFA_DRIVER_VERSION),
+		       FFA_MINOR_VERSION(FFA_DRIVER_VERSION));
+		return -EINVAL;
+	}
+
 	if (ver.a0 < FFA_MIN_VERSION) {
 		pr_err("Incompatible v%d.%d! Earliest supported v%d.%d\n",
 		       FFA_MAJOR_VERSION(ver.a0), FFA_MINOR_VERSION(ver.a0),
-- 
2.39.5