[MODERATED] [patch 07/11] [PATCH v2 07/10] Linux Patch #7

[konrad.wilk@oracle.com]

We do a lot of things in the check_bugs() - one of the first
things we do is identify_boot_cpu() which calls identify_cpu()
which calls this_cpu->init.

Once identify_boot_cpu() is done _then_ it walks through the
spectre_v2_select_mitigation() and alternative_assembler().

If there are some CPU fix ups _after_ spectre_v2 is done
we can't activate those on the BSP as we have already
called 'this_cpu->init'. Hence add a new function to
fixup CPUs.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
 arch/x86/include/asm/processor.h | 1 +
 arch/x86/kernel/cpu/bugs.c       | 1 +
 arch/x86/kernel/cpu/common.c     | 8 ++++++++
 arch/x86/kernel/cpu/cpu.h        | 1 +
 4 files changed, 11 insertions(+)

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index b0ccd4847a58..b22bc9be2385 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -195,6 +195,7 @@ extern void init_amd_cacheinfo(struct cpuinfo_x86 *c);
 
 extern void detect_extended_topology(struct cpuinfo_x86 *c);
 extern void detect_ht(struct cpuinfo_x86 *c);
+extern void apply_cpu_fixes(void);
 
 #ifdef CONFIG_X86_32
 extern int have_cpuid_p(void);
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index b8513a93f4b8..f02443b331f5 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -80,6 +80,7 @@ void __init check_bugs(void)
 	if (!direct_gbpages)
 		set_memory_4k((unsigned long)__va(0), 1);
 #endif
+	apply_cpu_fixes();
 }
 
 /* The kernel command line selection */
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index f7d80658cced..a59f7902a7fa 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -955,6 +955,12 @@ static void __init cpu_set_bug_bits(struct cpuinfo_x86 *c)
 	setup_force_cpu_bug(X86_BUG_CPU_SSB);
 };
 
+void apply_cpu_fixes(void)
+{
+	if (this_cpu->c_bug_fix)
+		this_cpu->c_bug_fix(&boot_cpu_data);
+}
+
 /*
  * Do minimum CPU detection early.
  * Fields really needed: vendor, cpuid_level, family, model, mask,
@@ -1311,6 +1317,8 @@ static void identify_cpu(struct cpuinfo_x86 *c)
 #ifdef CONFIG_NUMA
 	numa_add_cpu(smp_processor_id());
 #endif
+	if (this_cpu->c_bug_fix)
+		this_cpu->c_bug_fix(c);
 }
 
 /*
diff --git a/arch/x86/kernel/cpu/cpu.h b/arch/x86/kernel/cpu/cpu.h
index e806b11a99af..7081634caac5 100644
--- a/arch/x86/kernel/cpu/cpu.h
+++ b/arch/x86/kernel/cpu/cpu.h
@@ -15,6 +15,7 @@ struct cpu_dev {
 	void		(*c_identify)(struct cpuinfo_x86 *);
 	void		(*c_detect_tlb)(struct cpuinfo_x86 *);
 	void		(*c_bsp_resume)(struct cpuinfo_x86 *);
+	void		(*c_bug_fix)(struct cpuinfo_x86 *);
 	int		c_x86_vendor;
 #ifdef CONFIG_X86_32
 	/* Optional vendor specific routine to obtain the cache size. */
-- 
2.14.3