linux-kernel - [PATCH v2] x86: Quark: Add if/else to setup

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Date:	Fri, 26 Sep 2014 18:55:18 +0100
From:	Bryan O'Donoghue <pure.logic@...us-software.ie>
To:	hpa@...or.com, mingo@...hat.com, tglx@...utronix.de,
	davej@...hat.com, hmh@....eng.br, boon.leong.ong@...el.com
Cc:	x86@...nel.org, linux-kernel@...r.kernel.org,
	Bryan O'Donoghue <pure.logic@...us-software.ie>
Subject: [PATCH v2] x86: Quark: Add if/else to setup_arch for Quark TLB bug

Quark X1000 incorrectly advertises PGE. In later stages of boot
specifically in early_init_intel we setup_clear_cpu_cap for PGE.
At this point in time cpu_has_pge() will still be true.

Use the boot_cpu_data to decide if __flush_tlb_all() or __flush_tlb()
should be called subsequent to loading CR3

Signed-off-by: Bryan O'Donoghue <pure.logic@...us-software.ie>
---
 arch/x86/kernel/setup.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 41ead8d..980c3c3 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -879,7 +879,21 @@ void __init setup_arch(char **cmdline_p)
 			KERNEL_PGD_PTRS);
 
 	load_cr3(swapper_pg_dir);
-	__flush_tlb_all();
+
+	/*
+	 * Flush the TLB after loading CR3
+	 *
+	 * Quark X1000 wrongly advertises PGE. Use boot_cpu_data to
+	 * to make sure ithe TLB is flushed correctly in the early
+	 * stage of setup_arch() for Quark X1000.
+	 * X86_FEATURE_PGE flag is only setup later stage at
+	 * early_cpu_init();
+	 */
+	if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
+	    boot_cpu_data.x86 == 5 && boot_cpu_data.x86_model == 9)
+		__flush_tlb();
+	else
+		__flush_tlb_all();
 #else
 	printk(KERN_INFO "Command line: %s\n", boot_command_line);
 #endif
-- 
1.9.1

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