diff options
| -rw-r--r-- | arch/x86/kernel/cpu/microcode/intel.c | 123 |
1 files changed, 120 insertions, 3 deletions
diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c index d49a4e6ea477..5207c5a4ac69 100644 --- a/arch/x86/kernel/cpu/microcode/intel.c +++ b/arch/x86/kernel/cpu/microcode/intel.c @@ -16,9 +16,11 @@ #include <linux/uaccess.h> #include <linux/initrd.h> #include <linux/kernel.h> +#include <linux/delay.h> #include <linux/slab.h> #include <linux/cpu.h> #include <linux/uio.h> +#include <linux/io.h> #include <linux/mm.h> #include <asm/cpu_device_id.h> @@ -33,6 +35,15 @@ static const char ucode_path[] = "kernel/x86/microcode/GenuineIntel.bin"; #define UCODE_BSP_LOADED ((struct microcode_intel *)0x1UL) +/* Defines for the microcode staging mailbox interface */ +#define MBOX_REG_NUM 4 +#define MBOX_REG_SIZE sizeof(u32) + +#define MBOX_CONTROL_OFFSET 0x0 +#define MBOX_STATUS_OFFSET 0x4 + +#define MASK_MBOX_CTRL_ABORT BIT(0) + /* Current microcode patch used in early patching on the APs. */ static struct microcode_intel *ucode_patch_va __read_mostly; static struct microcode_intel *ucode_patch_late __read_mostly; @@ -317,13 +328,119 @@ static __init struct microcode_intel *scan_microcode(void *data, size_t size, } /* - * Handle the staging process using the mailbox MMIO interface. + * Prepare for a new microcode transfer: reset hardware and record the + * image size. + */ +static void init_stage(struct staging_state *ss) +{ + ss->ucode_len = get_totalsize(&ucode_patch_late->hdr); + + /* + * Abort any ongoing process, effectively resetting the device. + * Unlike regular mailbox data processing requests, this + * operation does not require a status check. + */ + writel(MASK_MBOX_CTRL_ABORT, ss->mmio_base + MBOX_CONTROL_OFFSET); +} + +/* + * Update the chunk size and decide whether another chunk can be sent. + * This accounts for remaining data and retry limits. + */ +static bool can_send_next_chunk(struct staging_state *ss, int *err) +{ + /* A page size or remaining bytes if this is the final chunk */ + ss->chunk_size = min(PAGE_SIZE, ss->ucode_len - ss->offset); + + /* + * Each microcode image is divided into chunks, each at most + * one page size. A 10-chunk image would typically require 10 + * transactions. + * + * However, the hardware managing the mailbox has limited + * resources and may not cache the entire image, potentially + * requesting the same chunk multiple times. + * + * To tolerate this behavior, allow up to twice the expected + * number of transactions (i.e., a 10-chunk image can take up to + * 20 attempts). + * + * If the number of attempts exceeds this limit, treat it as + * exceeding the maximum allowed transfer size. + */ + if (ss->bytes_sent + ss->chunk_size > ss->ucode_len * 2) { + *err = -EMSGSIZE; + return false; + } + + *err = 0; + return true; +} + +/* + * Determine whether staging is complete: either the hardware signaled + * the end offset, or no more transactions are permitted (retry limit + * reached). + */ +static inline bool staging_is_complete(struct staging_state *ss, int *err) +{ + return (ss->offset == UINT_MAX) || !can_send_next_chunk(ss, err); +} + +/* + * Transmit a chunk of the microcode image to the hardware. + * Return 0 on success, or an error code on failure. + */ +static int send_data_chunk(struct staging_state *ss, void *ucode_ptr __maybe_unused) +{ + pr_debug_once("Staging mailbox loading code needs to be implemented.\n"); + return -EPROTONOSUPPORT; +} + +/* + * Retrieve the next offset from the hardware response. + * Return 0 on success, or an error code on failure. + */ +static int fetch_next_offset(struct staging_state *ss) +{ + pr_debug_once("Staging mailbox response handling code needs to be implemented.\n"); + return -EPROTONOSUPPORT; +} + +/* + * Handle the staging process using the mailbox MMIO interface. The + * microcode image is transferred in chunks until completion. * Return 0 on success or an error code on failure. */ static int do_stage(u64 mmio_pa) { - pr_debug_once("Staging implementation is pending.\n"); - return -EPROTONOSUPPORT; + struct staging_state ss = {}; + int err; + + ss.mmio_base = ioremap(mmio_pa, MBOX_REG_NUM * MBOX_REG_SIZE); + if (WARN_ON_ONCE(!ss.mmio_base)) + return -EADDRNOTAVAIL; + + init_stage(&ss); + + /* Perform the staging process while within the retry limit */ + while (!staging_is_complete(&ss, &err)) { + /* Send a chunk of microcode each time: */ + err = send_data_chunk(&ss, ucode_patch_late); + if (err) + break; + /* + * Then, ask the hardware which piece of the image it + * needs next. The same piece may be sent more than once. + */ + err = fetch_next_offset(&ss); + if (err) + break; + } + + iounmap(ss.mmio_base); + + return err; } static void stage_microcode(void) |