Patch "x86/intel/quark: Switch off CR4.PGE so TLB flush uses CR3 instead" has been added to the 3.14-stable tree

[g***@linuxfoundation.org]

This is a note to let you know that I've just added the patch titled

x86/intel/quark: Switch off CR4.PGE so TLB flush uses CR3 instead

to the 3.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
x86-intel-quark-switch-off-cr4.pge-so-tlb-flush-uses-cr3-instead.patch
and it can be found in the queue-3.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,

From ee1b5b165c0a2f04d2107e634e51f05d0eb107de Mon Sep 17 00:00:00 2001

From: Bryan O'Donoghue <***@nexus-software.ie>
Date: Wed, 24 Sep 2014 00:26:24 +0100
Subject: x86/intel/quark: Switch off CR4.PGE so TLB flush uses CR3 instead

From: Bryan O'Donoghue <***@nexus-software.ie>

commit ee1b5b165c0a2f04d2107e634e51f05d0eb107de upstream.

Quark x1000 advertises PGE via the standard CPUID method
PGE bits exist in Quark X1000's PTEs. In order to flush
an individual PTE it is necessary to reload CR3 irrespective
of the PTE.PGE bit.

See Quark Core_DevMan_001.pdf section 6.4.11

This bug was fixed in Galileo kernels, unfixed vanilla kernels are expected to
crash and burn on this platform.

Signed-off-by: Bryan O'Donoghue <***@nexus-software.ie>
Cc: Borislav Petkov <***@alien8.de>
Link: http://lkml.kernel.org/r/1411514784-14885-1-git-send-email-***@nexus-software.ie
Signed-off-by: Ingo Molnar <***@kernel.org>
Signed-off-by: Greg Kroah-Hartman <***@linuxfoundation.org>

---
arch/x86/kernel/cpu/intel.c | 15 +++++++++++++++
1 file changed, 15 insertions(+)

--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -153,6 +153,21 @@ static void early_init_intel(struct cpui
setup_clear_cpu_cap(X86_FEATURE_ERMS);
}
}
+
+ /*
+ * Intel Quark Core DevMan_001.pdf section 6.4.11
+ * "The operating system also is required to invalidate (i.e., flush)
+ * the TLB when any changes are made to any of the page table entries.
+ * The operating system must reload CR3 to cause the TLB to be flushed"
+ *
+ * As a result cpu_has_pge() in arch/x86/include/asm/tlbflush.h should
+ * be false so that __flush_tlb_all() causes CR3 insted of CR4.PGE
+ * to be modified
+ */
+ if (c->x86 == 5 && c->x86_model == 9) {
+ pr_info("Disabling PGE capability bit\n");
+ setup_clear_cpu_cap(X86_FEATURE_PGE);
+ }
}

#ifdef CONFIG_X86_32


Patches currently in stable-queue which might be from ***@nexus-software.ie are

queue-3.14/x86-intel-quark-switch-off-cr4.pge-so-tlb-flush-uses-cr3-instead.patch