From: Xiaochun Lee <lix...@lenovo.com>

When enabled Firmware First mode in UEFI and
all banks are Machine Check Bank, then to make
it non-modifiable so that it can't be reenable
from sysfs again.

Signed-off-by: Xiaochun Lee <lix...@lenovo.com>
---
 arch/x86/kernel/cpu/mce/core.c     |  4 ++--
 arch/x86/kernel/cpu/mce/intel.c    | 15 ++++++++++++++-
 arch/x86/kernel/cpu/mce/internal.h |  1 +
 3 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
index 743370e..cee4d70 100644
--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -2164,7 +2164,7 @@ static ssize_t set_ignore_ce(struct device *s,
                        mce_timer_delete_all();
                        on_each_cpu(mce_disable_cmci, NULL, 1);
                        mca_cfg.ignore_ce = true;
-               } else {
+               } else if (!mca_cfg.allbanks_is_mcbank) {
                        /* enable ce features */
                        mca_cfg.ignore_ce = false;
                        on_each_cpu(mce_enable_ce, (void *)1, 1);
@@ -2190,7 +2190,7 @@ static ssize_t set_cmci_disabled(struct device *s,
                        /* disable cmci */
                        on_each_cpu(mce_disable_cmci, NULL, 1);
                        mca_cfg.cmci_disabled = true;
-               } else {
+               } else if (!mca_cfg.allbanks_is_mcbank) {
                        /* enable cmci */
                        mca_cfg.cmci_disabled = false;
                        on_each_cpu(mce_enable_ce, NULL, 1);
diff --git a/arch/x86/kernel/cpu/mce/intel.c b/arch/x86/kernel/cpu/mce/intel.c
index e43eb67..e15b573 100644
--- a/arch/x86/kernel/cpu/mce/intel.c
+++ b/arch/x86/kernel/cpu/mce/intel.c
@@ -267,6 +267,7 @@ static void cmci_discover(int banks)
        unsigned long flags;
        int i;
        int bios_wrong_thresh = 0;
+       unsigned int mce_bank_count = 0;
 
        raw_spin_lock_irqsave(&cmci_discover_lock, flags);
        for (i = 0; i < banks; i++) {
@@ -277,8 +278,10 @@ static void cmci_discover(int banks)
                        continue;
 
                /* Skip banks in firmware first mode */
-               if (test_bit(i, mce_banks_ce_disabled))
+               if (test_bit(i, mce_banks_ce_disabled)) {
+                       mce_bank_count++;
                        continue;
+               }
 
                rdmsrl(MSR_IA32_MCx_CTL2(i), val);
 
@@ -330,6 +333,16 @@ static void cmci_discover(int banks)
                pr_info_once(
                        "bios_cmci_threshold: Make sure your BIOS supports this 
boot option\n");
        }
+       /*
+        * After the loop exit, if the mce_bank_count
+        * equal to the banks, it illustrate all the
+        * banks are belong to the list of Machine
+        * Check Bank, so here set sysfs interface
+        * no-modifiable in FF mode.
+        */
+       if (banks == mce_bank_count)
+               mca_cfg.allbanks_is_mcbank = true;
+
 }
 
 /*
diff --git a/arch/x86/kernel/cpu/mce/internal.h 
b/arch/x86/kernel/cpu/mce/internal.h
index 43031db..7949c01 100644
--- a/arch/x86/kernel/cpu/mce/internal.h
+++ b/arch/x86/kernel/cpu/mce/internal.h
@@ -110,6 +110,7 @@ struct mca_config {
        bool dont_log_ce;
        bool cmci_disabled;
        bool ignore_ce;
+       bool allbanks_is_mcbank;
 
        __u64 lmce_disabled             : 1,
              disabled                  : 1,
-- 
1.8.3.1


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