lkml.org 
[lkml]   [2023]   [Oct]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    Subject[tip: x86/microcode] x86/microcode: Clarify the late load logic
    The following commit has been merged into the x86/microcode branch of tip:

    Commit-ID: 6f059e634dcd0d725854514c94c114bbdd83950d
    Gitweb: https://git.kernel.org/tip/6f059e634dcd0d725854514c94c114bbdd83950d
    Author: Thomas Gleixner <tglx@linutronix.de>
    AuthorDate: Mon, 02 Oct 2023 13:59:57 +02:00
    Committer: Borislav Petkov (AMD) <bp@alien8.de>
    CommitterDate: Tue, 24 Oct 2023 15:05:54 +02:00

    x86/microcode: Clarify the late load logic

    reload_store() is way too complicated. Split the inner workings out and
    make the following enhancements:

    - Taint the kernel only when the microcode was actually updated. If. e.g.
    the rendezvous fails, then nothing happened and there is no reason for
    tainting.

    - Return useful error codes

    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
    Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
    Reviewed-by: Nikolay Borisov <nik.borisov@suse.com>
    Link: https://lore.kernel.org/r/20231002115903.145048840@linutronix.de
    ---
    arch/x86/kernel/cpu/microcode/core.c | 41 ++++++++++++---------------
    1 file changed, 19 insertions(+), 22 deletions(-)

    diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c
    index 7af1b60..63c4e12 100644
    --- a/arch/x86/kernel/cpu/microcode/core.c
    +++ b/arch/x86/kernel/cpu/microcode/core.c
    @@ -362,11 +362,11 @@ static int microcode_reload_late(void)
    pr_info("Reload succeeded, microcode revision: 0x%x -> 0x%x\n",
    old, boot_cpu_data.microcode);
    microcode_check(&prev_info);
    + add_taint(TAINT_CPU_OUT_OF_SPEC, LOCKDEP_STILL_OK);
    } else {
    pr_info("Reload failed, current microcode revision: 0x%x\n",
    boot_cpu_data.microcode);
    }
    -
    return ret;
    }

    @@ -399,40 +399,37 @@ static bool ensure_cpus_are_online(void)
    return true;
    }

    +static int ucode_load_late_locked(void)
    +{
    + if (!ensure_cpus_are_online())
    + return -EBUSY;
    +
    + switch (microcode_ops->request_microcode_fw(0, &microcode_pdev->dev)) {
    + case UCODE_NEW:
    + return microcode_reload_late();
    + case UCODE_NFOUND:
    + return -ENOENT;
    + default:
    + return -EBADFD;
    + }
    +}
    +
    static ssize_t reload_store(struct device *dev,
    struct device_attribute *attr,
    const char *buf, size_t size)
    {
    - enum ucode_state tmp_ret = UCODE_OK;
    - int bsp = boot_cpu_data.cpu_index;
    unsigned long val;
    - ssize_t ret = 0;
    + ssize_t ret;

    ret = kstrtoul(buf, 0, &val);
    if (ret || val != 1)
    return -EINVAL;

    cpus_read_lock();
    -
    - if (!ensure_cpus_are_online()) {
    - ret = -EBUSY;
    - goto put;
    - }
    -
    - tmp_ret = microcode_ops->request_microcode_fw(bsp, &microcode_pdev->dev);
    - if (tmp_ret != UCODE_NEW)
    - goto put;
    -
    - ret = microcode_reload_late();
    -put:
    + ret = ucode_load_late_locked();
    cpus_read_unlock();

    - if (ret == 0)
    - ret = size;
    -
    - add_taint(TAINT_CPU_OUT_OF_SPEC, LOCKDEP_STILL_OK);
    -
    - return ret;
    + return ret ? : size;
    }

    static DEVICE_ATTR_WO(reload);
    \
     
     \ /
      Last update: 2023-10-24 15:23    [W:4.136 / U:0.704 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site