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    Subject[PATCH] fix x86 microcode driver handling of multiple matching revisions
    When multiple updates matching a given CPU are found in the update file, the
    action taken by the microcode update driver was inappropriate:

    - when lower revision microcode was found before matching or higher revision
    one, the driver would needlessly complain that it would not downgrade the
    CPU
    - when microcode matching the currently installed revision was found before
    newer revision code, no update would actually take place

    To change this behavior, the driver now concludes about possibly updates and
    issues messages only when the entire input was parsed.

    Additionally, this adds back (in different places, and conditionalized upon
    a new module option) some messages removed by a previous patch.

    Signed-off-by: Jan Beulich <jbeulich@novell.com>

    diff -Npru /home/jbeulich/tmp/linux-2.6.17-rc2/arch/i386/kernel/microcode.c
    2.6.17-rc2-x86-microcode/arch/i386/kernel/microcode.c
    --- /home/jbeulich/tmp/linux-2.6.17-rc2/arch/i386/kernel/microcode.c 2006-04-26 10:55:11.000000000 +0200
    +++ 2.6.17-rc2-x86-microcode/arch/i386/kernel/microcode.c 2006-03-27 22:46:38.000000000 +0200
    @@ -91,7 +91,10 @@ MODULE_DESCRIPTION("Intel CPU (IA-32) Mi
    MODULE_AUTHOR("Tigran Aivazian <tigran@veritas.com>");
    MODULE_LICENSE("GPL");

    -#define MICROCODE_VERSION "1.14"
    +static int verbose;
    +module_param(verbose, int, 0644);
    +
    +#define MICROCODE_VERSION "1.14a"

    #define DEFAULT_UCODE_DATASIZE (2000) /* 2000 bytes */
    #define MC_HEADER_SIZE (sizeof (microcode_header_t)) /* 48 bytes */
    @@ -122,14 +125,15 @@ static unsigned int user_buffer_size; /*

    typedef enum mc_error_code {
    MC_SUCCESS = 0,
    - MC_NOTFOUND = 1,
    - MC_MARKED = 2,
    - MC_ALLOCATED = 3,
    + MC_IGNORED = 1,
    + MC_NOTFOUND = 2,
    + MC_MARKED = 3,
    + MC_ALLOCATED = 4,
    } mc_error_code_t;

    static struct ucode_cpu_info {
    unsigned int sig;
    - unsigned int pf;
    + unsigned int pf, orig_pf;
    unsigned int rev;
    unsigned int cksum;
    mc_error_code_t err;
    @@ -164,6 +168,7 @@ static void collect_cpu_info (void *unus
    rdmsr(MSR_IA32_PLATFORM_ID, val[0], val[1]);
    uci->pf = 1 << ((val[1] >> 18) & 7);
    }
    + uci->orig_pf = uci->pf;
    }

    wrmsr(MSR_IA32_UCODE_REV, 0, 0);
    @@ -197,21 +202,33 @@ static inline void mark_microcode_update
    pr_debug(" Checksum 0x%x\n", cksum);

    if (mc_header->rev < uci->rev) {
    - printk(KERN_ERR "microcode: CPU%d not 'upgrading' to earlier revision"
    - " 0x%x (current=0x%x)\n", cpu_num, mc_header->rev, uci->rev);
    - goto out;
    + if (uci->err == MC_NOTFOUND) {
    + uci->err = MC_IGNORED;
    + uci->cksum = mc_header->rev;
    + } else if (uci->err == MC_IGNORED && uci->cksum < mc_header->rev)
    + uci->cksum = mc_header->rev;
    } else if (mc_header->rev == uci->rev) {
    - /* notify the caller of success on this cpu */
    - uci->err = MC_SUCCESS;
    - goto out;
    + if (uci->err < MC_MARKED) {
    + /* notify the caller of success on this cpu */
    + uci->err = MC_SUCCESS;
    + }
    + } else if (uci->err != MC_ALLOCATED || mc_header->rev > uci->mc->hdr.rev) {
    + pr_debug("microcode: CPU%d found a matching microcode update with "
    + " revision 0x%x (current=0x%x)\n", cpu_num, mc_header->rev, uci->rev);
    + uci->cksum = cksum;
    + uci->pf = pf; /* keep the original mc pf for cksum calculation */
    + uci->err = MC_MARKED; /* found the match */
    + for_each_online_cpu(cpu_num) {
    + if (ucode_cpu_info[cpu_num].mc == uci->mc) {
    + uci->mc = NULL;
    + break;
    + }
    + }
    + if (uci->mc != NULL) {
    + vfree(uci->mc);
    + uci->mc = NULL;
    + }
    }
    -
    - pr_debug("microcode: CPU%d found a matching microcode update with "
    - " revision 0x%x (current=0x%x)\n", cpu_num, mc_header->rev, uci->rev);
    - uci->cksum = cksum;
    - uci->pf = pf; /* keep the original mc pf for cksum calculation */
    - uci->err = MC_MARKED; /* found the match */
    -out:
    return;
    }

    @@ -253,10 +270,8 @@ static int find_matching_ucodes (void)

    for_each_online_cpu(cpu_num) {
    struct ucode_cpu_info *uci = ucode_cpu_info + cpu_num;
    - if (uci->err != MC_NOTFOUND) /* already found a match or not an online cpu*/
    - continue;

    - if (sigmatch(mc_header.sig, uci->sig, mc_header.pf, uci->pf))
    + if (sigmatch(mc_header.sig, uci->sig, mc_header.pf, uci->orig_pf))
    mark_microcode_update(cpu_num, &mc_header, mc_header.sig, mc_header.pf,
    mc_header.cksum);
    }

    @@ -295,9 +310,8 @@ static int find_matching_ucodes (void)
    }
    for_each_online_cpu(cpu_num) {
    struct ucode_cpu_info *uci = ucode_cpu_info + cpu_num;
    - if (uci->err != MC_NOTFOUND) /* already found a match or not an online cpu*/
    - continue;
    - if (sigmatch(ext_sig.sig, uci->sig, ext_sig.pf, uci->pf)) {
    +
    + if (sigmatch(ext_sig.sig, uci->sig, ext_sig.pf, uci->orig_pf)) {
    mark_microcode_update(cpu_num, &mc_header, ext_sig.sig, ext_sig.pf,
    ext_sig.cksum);
    }
    }
    @@ -368,6 +382,13 @@ static void do_update_one (void * unused
    struct ucode_cpu_info *uci = ucode_cpu_info + cpu_num;

    if (uci->mc == NULL) {
    + if (verbose) {
    + if (uci->err == MC_SUCCESS)
    + printk(KERN_INFO "microcode: CPU%d already at revision 0x%x\n",
    + cpu_num, uci->rev);
    + else
    + printk(KERN_INFO "microcode: No new microcode data for CPU%d\n", cpu_num);
    + }
    return;
    }

    @@ -426,6 +447,9 @@ out_free:
    ucode_cpu_info[j].mc = NULL;
    }
    }
    + if (ucode_cpu_info[i].err == MC_IGNORED && verbose)
    + printk(KERN_WARNING "microcode: CPU%d not 'upgrading' to earlier revision"
    + " 0x%x (current=0x%x)\n", i, ucode_cpu_info[i].cksum, ucode_cpu_info[i].rev);
    }
    out:
    return error;

    -
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