Two fixes for x86:

- Remove the __force_oder definiton from the kaslr boot code as it is
     already defined in the page table code which makes GCC 10 builds fail
     because it changed the default to -fno-common.
 
   - Address the AMD erratum 1054 concerning the IRPERF capability and
     enable the Instructions Retired fixed counter on machines which are not
     affected by the erratum.
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Merge tag 'x86-urgent-2020-02-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 fixes from Thomas Gleixner:
 "Two fixes for x86:

   - Remove the __force_oder definiton from the kaslr boot code as it is
     already defined in the page table code which makes GCC 10 builds
     fail because it changed the default to -fno-common.

   - Address the AMD erratum 1054 concerning the IRPERF capability and
     enable the Instructions Retired fixed counter on machines which are
     not affected by the erratum"

* tag 'x86-urgent-2020-02-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/cpu/amd: Enable the fixed Instructions Retired counter IRPERF
  x86/boot/compressed: Don't declare __force_order in kaslr_64.c

arch/x86/boot/compressed/kaslr_64.c

@@ -29,9 +29,6 @@
 #define __PAGE_OFFSET __PAGE_OFFSET_BASE
 #include "../../mm/ident_map.c"
 
-/* Used by pgtable.h asm code to force instruction serialization. */
-unsigned long __force_order;
-
 /* Used to track our page table allocation area. */
 struct alloc_pgt_data {
 	unsigned char *pgt_buf;

arch/x86/include/asm/msr-index.h

@@ -512,6 +512,8 @@
 #define MSR_K7_HWCR			0xc0010015
 #define MSR_K7_HWCR_SMMLOCK_BIT		0
 #define MSR_K7_HWCR_SMMLOCK		BIT_ULL(MSR_K7_HWCR_SMMLOCK_BIT)
+#define MSR_K7_HWCR_IRPERF_EN_BIT	30
+#define MSR_K7_HWCR_IRPERF_EN		BIT_ULL(MSR_K7_HWCR_IRPERF_EN_BIT)
 #define MSR_K7_FID_VID_CTL		0xc0010041
 #define MSR_K7_FID_VID_STATUS		0xc0010042
 

arch/x86/kernel/cpu/amd.c

@@ -28,6 +28,7 @@
 
 static const int amd_erratum_383[];
 static const int amd_erratum_400[];
+static const int amd_erratum_1054[];
 static bool cpu_has_amd_erratum(struct cpuinfo_x86 *cpu, const int *erratum);
 
 /*
@@ -972,6 +973,15 @@ static void init_amd(struct cpuinfo_x86 *c)
 	/* AMD CPUs don't reset SS attributes on SYSRET, Xen does. */
 	if (!cpu_has(c, X86_FEATURE_XENPV))
 		set_cpu_bug(c, X86_BUG_SYSRET_SS_ATTRS);
+
+	/*
+	 * Turn on the Instructions Retired free counter on machines not
+	 * susceptible to erratum #1054 "Instructions Retired Performance
+	 * Counter May Be Inaccurate".
+	 */
+	if (cpu_has(c, X86_FEATURE_IRPERF) &&
+	    !cpu_has_amd_erratum(c, amd_erratum_1054))
+		msr_set_bit(MSR_K7_HWCR, MSR_K7_HWCR_IRPERF_EN_BIT);
 }
 
 #ifdef CONFIG_X86_32
@@ -1099,6 +1109,10 @@ static const int amd_erratum_400[] =
 static const int amd_erratum_383[] =
 	AMD_OSVW_ERRATUM(3, AMD_MODEL_RANGE(0x10, 0, 0, 0xff, 0xf));
 
+/* #1054: Instructions Retired Performance Counter May Be Inaccurate */
+static const int amd_erratum_1054[] =
+	AMD_OSVW_ERRATUM(0, AMD_MODEL_RANGE(0x17, 0, 0, 0x2f, 0xf));
+
 
 static bool cpu_has_amd_erratum(struct cpuinfo_x86 *cpu, const int *erratum)
 {