x86/platform/amd: move final timeout check to after final sleep

JIRA: https://issues.redhat.com/browse/RHEL-102859

commit f8afb12
Author: Jake Hillion <jake@hillion.co.uk>
Date:   Thu Jun 5 19:09:26 2025 +0100

    x86/platform/amd: move final timeout check to after final sleep

    __hsmp_send_message sleeps between result read attempts and has a
    timeout of 100ms. Under extreme load it's possible for these sleeps to
    take a long time, exceeding the 100ms. In this case the current code
    does not check the register and fails with ETIMEDOUT.

    Refactor the loop to ensure there is at least one read of the register
    after a sleep of any duration. This removes instances of ETIMEDOUT with
    a single caller, even with a misbehaving scheduler. Tested on AMD
    Bergamo machines.

    Suggested-by: Blaise Sanouillet <linux@blaise.sanouillet.com>
    Reviewed-by: Suma Hegde <suma.hegde@amd.com>
    Tested-by: Suma Hegde <suma.hegde@amd.com>
    Signed-off-by: Jake Hillion <jake@hillion.co.uk>
    Link: https://lore.kernel.org/r/20250605-amd-hsmp-v2-1-a811bc3dd74a@hillion.co.uk
    Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
    Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

Signed-off-by: David Arcari <darcari@redhat.com>

Author: darcari

drivers/platform/x86/amd/hsmp/hsmp.c

@@ -97,7 +97,7 @@ static int __hsmp_send_message(struct hsmp_socket *sock, struct hsmp_message *ms
 	short_sleep = jiffies + msecs_to_jiffies(HSMP_SHORT_SLEEP);
 	timeout	= jiffies + msecs_to_jiffies(HSMP_MSG_TIMEOUT);
 
-	while (time_before(jiffies, timeout)) {
+	while (true) {
 		ret = sock->amd_hsmp_rdwr(sock, mbinfo->msg_resp_off, &mbox_status, HSMP_RD);
 		if (ret) {
 			dev_err(sock->dev, "Error %d reading mailbox status\n", ret);
@@ -106,6 +106,10 @@ static int __hsmp_send_message(struct hsmp_socket *sock, struct hsmp_message *ms
 
 		if (mbox_status != HSMP_STATUS_NOT_READY)
 			break;
+
+		if (!time_before(jiffies, timeout))
+			break;
+
 		if (time_before(jiffies, short_sleep))
 			usleep_range(50, 100);
 		else