platform/x86/amd/pmc: Detect when STB is not available

JIRA: https://issues.redhat.com/browse/RHEL-68176
CVE: CVE-2024-53072

commit bceec87
Author: Corey Hickey <bugfood-c@fatooh.org>
Date:   Mon Oct 28 11:02:41 2024 -0700

    platform/x86/amd/pmc: Detect when STB is not available

    Loading the amd_pmc module as:

        amd_pmc enable_stb=1

    ...can result in the following messages in the kernel ring buffer:

        amd_pmc AMDI0009:00: SMU cmd failed. err: 0xff
        ioremap on RAM at 0x0000000000000000 - 0x0000000000ffffff
        WARNING: CPU: 10 PID: 2151 at arch/x86/mm/ioremap.c:217 __ioremap_caller+0x2cd/0x340

    Further debugging reveals that this occurs when the requests for
    S2D_PHYS_ADDR_LOW and S2D_PHYS_ADDR_HIGH return a value of 0,
    indicating that the STB is inaccessible. To prevent the ioremap
    warning and provide clarity to the user, handle the invalid address
    and display an error message.

    Link: https://lore.kernel.org/platform-driver-x86/c588ff5d-3e04-4549-9a86-284b9b4419ba@amd.com
    Fixes: 3d7d407 ("platform/x86: amd-pmc: Add support for AMD Spill to DRAM STB feature")
    Acked-by: Shyam Sundar S K <Shyam-sundar.S-k@amd.com>
    Signed-off-by: Corey Hickey <bugfood-c@fatooh.org>
    Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
    Link: https://lore.kernel.org/r/20241028180241.1341624-1-bugfood-ml@fatooh.org
    Reviewed-by: Hans de Goede <hdegoede@redhat.com>
    Signed-off-by: Hans de Goede <hdegoede@redhat.com>

Signed-off-by: CKI Backport Bot <cki-ci-bot+cki-gitlab-backport-bot@redhat.com>

Author: CKI Backport Bot

drivers/platform/x86/amd/pmc/pmc.c

@@ -993,6 +993,11 @@ static int amd_pmc_s2d_init(struct amd_pmc_dev *dev)
 	amd_pmc_send_cmd(dev, S2D_PHYS_ADDR_LOW, &phys_addr_low, dev->s2d_msg_id, true);
 	amd_pmc_send_cmd(dev, S2D_PHYS_ADDR_HIGH, &phys_addr_hi, dev->s2d_msg_id, true);
 
+	if (!phys_addr_hi && !phys_addr_low) {
+		dev_err(dev->dev, "STB is not enabled on the system; disable enable_stb or contact system vendor\n");
+		return -EINVAL;
+	}
+
 	stb_phys_addr = ((u64)phys_addr_hi << 32 | phys_addr_low);
 
 	/* Clear msg_port for other SMU operation */