x86/microcode: Move away from using a fake platform device

Downloading firmware needs a device to hang off of, and so a platform device
seemed like the simplest way to do this.  Now that we have a faux device
interface, use that instead as this "microcode device" is not anything
resembling a platform device at all.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Sohil Mehta <sohil.mehta@intel.com>
Link: https://lore.kernel.org/2025070121-omission-small-9308@gregkh

diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c
index fe50eb5b7c4a35ba67da412f4685b36ac69e6be7..b92e09a87c6997f92eace5865b1c4887d55e3852 100644 (file)
--- a/arch/x86/kernel/cpu/microcode/core.c
+++ b/arch/x86/kernel/cpu/microcode/core.c
@@ -17,8 +17,8 @@
 
 #define pr_fmt(fmt) "microcode: " fmt
 
-#include <linux/platform_device.h>
 #include <linux/stop_machine.h>
+#include <linux/device/faux.h>
 #include <linux/syscore_ops.h>
 #include <linux/miscdevice.h>
 #include <linux/capability.h>
@@ -249,7 +249,7 @@ static void reload_early_microcode(unsigned int cpu)
 }
 
 /* fake device for request_firmware */
-static struct platform_device  *microcode_pdev;
+static struct faux_device *microcode_fdev;
 
 #ifdef CONFIG_MICROCODE_LATE_LOADING
 /*
@@ -690,7 +690,7 @@ static int load_late_locked(void)
        if (!setup_cpus())
                return -EBUSY;
 
-       switch (microcode_ops->request_microcode_fw(0, &microcode_pdev->dev)) {
+       switch (microcode_ops->request_microcode_fw(0, &microcode_fdev->dev)) {
        case UCODE_NEW:
                return load_late_stop_cpus(false);
        case UCODE_NEW_SAFE:
@@ -841,9 +841,9 @@ static int __init microcode_init(void)
        if (early_data.new_rev)
                pr_info_once("Updated early from: 0x%08x\n", early_data.old_rev);
 
-       microcode_pdev = platform_device_register_simple("microcode", -1, NULL, 0);
-       if (IS_ERR(microcode_pdev))
-               return PTR_ERR(microcode_pdev);
+       microcode_fdev = faux_device_create("microcode", NULL, NULL);
+       if (!microcode_fdev)
+               return -ENODEV;
 
        dev_root = bus_get_dev_root(&cpu_subsys);
        if (dev_root) {
@@ -862,7 +862,7 @@ static int __init microcode_init(void)
        return 0;
 
  out_pdev:
-       platform_device_unregister(microcode_pdev);
+       faux_device_destroy(microcode_fdev);
        return error;
 
 }