x86/mtrr: Add mtrr=debug command line option

Add a new command line option "mtrr=debug" for getting debug output
after building the new cache mode map. The output will include MTRR
register values and the resulting map.

Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/20230502120931.20719-13-jgross@suse.com
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 9e5bab29685ff0534fe82714dda5e20804c38ead..44a87ada7145143d2a142508422647ed8ecad3bb 100644 (file)
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3423,6 +3423,10 @@
                        [HW] Make the MicroTouch USB driver use raw coordinates
                        ('y', default) or cooked coordinates ('n')
 
+       mtrr=debug      [X86]
+                       Enable printing debug information related to MTRR
+                       registers at boot time.
+
        mtrr_chunk_size=nn[KMG] [X86]
                        used for mtrr cleanup. It is largest continuous chunk
                        that could hold holes aka. UC entries.

diff --git a/arch/x86/kernel/cpu/mtrr/generic.c b/arch/x86/kernel/cpu/mtrr/generic.c
index e0db6fc1bfd4557b815e9a5c7c41f50e978ed3a4..852031ef4780212b81eafedb943f4b3b7558ca45 100644 (file)
--- a/arch/x86/kernel/cpu/mtrr/generic.c
+++ b/arch/x86/kernel/cpu/mtrr/generic.c
@@ -41,6 +41,23 @@ struct cache_map {
        u64 fixed:1;
 };
 
+static bool mtrr_debug;
+
+static int __init mtrr_param_setup(char *str)
+{
+       int rc = 0;
+
+       if (!str)
+               return -EINVAL;
+       if (!strcmp(str, "debug"))
+               mtrr_debug = true;
+       else
+               rc = -EINVAL;
+
+       return rc;
+}
+early_param("mtrr", mtrr_param_setup);
+
 /*
  * CACHE_MAP_MAX is the maximum number of memory ranges in cache_map, where
  * no 2 adjacent ranges have the same cache mode (those would be merged).
@@ -515,6 +532,14 @@ void __init mtrr_build_map(void)
        pr_info("MTRR map: %u entries (%u fixed + %u variable; max %u), built from %u variable MTRRs\n",
                cache_map_n, cache_map_fixed, cache_map_n - cache_map_fixed,
                get_cache_map_size(), num_var_ranges + (mtrr_tom2 != 0));
+
+       if (mtrr_debug) {
+               for (i = 0; i < cache_map_n; i++) {
+                       pr_info("%3u: %016llx-%016llx %s\n", i,
+                               cache_map[i].start, cache_map[i].end - 1,
+                               mtrr_attrib_to_str(cache_map[i].type));
+               }
+       }
 }
 
 /* Copy the cache_map from __initdata memory to dynamically allocated one. */
@@ -721,8 +746,8 @@ static void __init print_fixed_last(void)
        if (!last_fixed_end)
                return;
 
-       pr_debug("  %05X-%05X %s\n", last_fixed_start,
-                last_fixed_end - 1, mtrr_attrib_to_str(last_fixed_type));
+       pr_info("  %05X-%05X %s\n", last_fixed_start,
+               last_fixed_end - 1, mtrr_attrib_to_str(last_fixed_type));
 
        last_fixed_end = 0;
 }
@@ -760,10 +785,10 @@ static void __init print_mtrr_state(void)
        unsigned int i;
        int high_width;
 
-       pr_debug("MTRR default type: %s\n",
-                mtrr_attrib_to_str(mtrr_state.def_type));
+       pr_info("MTRR default type: %s\n",
+               mtrr_attrib_to_str(mtrr_state.def_type));
        if (mtrr_state.have_fixed) {
-               pr_debug("MTRR fixed ranges %sabled:\n",
+               pr_info("MTRR fixed ranges %sabled:\n",
                        ((mtrr_state.enabled & MTRR_STATE_MTRR_ENABLED) &&
                         (mtrr_state.enabled & MTRR_STATE_MTRR_FIXED_ENABLED)) ?
                         "en" : "dis");
@@ -778,27 +803,27 @@ static void __init print_mtrr_state(void)
                /* tail */
                print_fixed_last();
        }
-       pr_debug("MTRR variable ranges %sabled:\n",
-                mtrr_state.enabled & MTRR_STATE_MTRR_ENABLED ? "en" : "dis");
+       pr_info("MTRR variable ranges %sabled:\n",
+               mtrr_state.enabled & MTRR_STATE_MTRR_ENABLED ? "en" : "dis");
        high_width = (boot_cpu_data.x86_phys_bits - (32 - PAGE_SHIFT) + 3) / 4;
 
        for (i = 0; i < num_var_ranges; ++i) {
                if (mtrr_state.var_ranges[i].mask_lo & MTRR_PHYSMASK_V)
-                       pr_debug("  %u base %0*X%05X000 mask %0*X%05X000 %s\n",
-                                i,
-                                high_width,
-                                mtrr_state.var_ranges[i].base_hi,
-                                mtrr_state.var_ranges[i].base_lo >> 12,
-                                high_width,
-                                mtrr_state.var_ranges[i].mask_hi,
-                                mtrr_state.var_ranges[i].mask_lo >> 12,
-                                mtrr_attrib_to_str(mtrr_state.var_ranges[i].base_lo &
+                       pr_info("  %u base %0*X%05X000 mask %0*X%05X000 %s\n",
+                               i,
+                               high_width,
+                               mtrr_state.var_ranges[i].base_hi,
+                               mtrr_state.var_ranges[i].base_lo >> 12,
+                               high_width,
+                               mtrr_state.var_ranges[i].mask_hi,
+                               mtrr_state.var_ranges[i].mask_lo >> 12,
+                               mtrr_attrib_to_str(mtrr_state.var_ranges[i].base_lo &
                                                    MTRR_PHYSBASE_TYPE));
                else
-                       pr_debug("  %u disabled\n", i);
+                       pr_info("  %u disabled\n", i);
        }
        if (mtrr_tom2)
-               pr_debug("TOM2: %016llx aka %lldM\n", mtrr_tom2, mtrr_tom2>>20);
+               pr_info("TOM2: %016llx aka %lldM\n", mtrr_tom2, mtrr_tom2>>20);
 }
 
 /* Grab all of the MTRR state for this CPU into *state */
@@ -833,7 +858,8 @@ bool __init get_mtrr_state(void)
                mtrr_tom2 &= 0xffffff800000ULL;
        }
 
-       print_mtrr_state();
+       if (mtrr_debug)
+               print_mtrr_state();
 
        mtrr_state_set = 1;