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Add upstream fix for 4.15

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This is from xen-devel and isn't yet in master.

Without it PV is broken.
This commit is contained in:
Simon Gaiser 2018-02-06 06:09:11 +01:00
parent f9db313392
commit d922e28b0b
2 changed files with 59 additions and 0 deletions
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56
patches.xen/x86-xen-init-gs-very-early-to-avoid-page-faults-with.patch Normal file
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@ -0,0 +1,56 @@
From d3c8038919ffb95553ff2b6878f6eae46579abe7 Mon Sep 17 00:00:00 2001
From: Juergen Gross <jgross@suse.com>
Date: Thu, 1 Feb 2018 13:40:19 +0100
Subject: [PATCH] x86/xen: init %gs very early to avoid page faults with stack
protector
When running as Xen pv guest %gs is initialized some time after
C code is started. Depending on stack protector usage this might be
too late, resulting in page faults.
So setup %gs and MSR_GS_BASE in assembly code already.
Cc: stable@vger.kernel.org
Signed-off-by: Juergen Gross <jgross@suse.com>
---
arch/x86/xen/xen-head.S | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/arch/x86/xen/xen-head.S b/arch/x86/xen/xen-head.S
index 497cc55a0c16..96f26e026783 100644
--- a/arch/x86/xen/xen-head.S
+++ b/arch/x86/xen/xen-head.S
@@ -9,7 +9,9 @@
#include <asm/boot.h>
#include <asm/asm.h>
+#include <asm/msr.h>
#include <asm/page_types.h>
+#include <asm/percpu.h>
#include <asm/unwind_hints.h>
#include <xen/interface/elfnote.h>
@@ -35,6 +37,20 @@ ENTRY(startup_xen)
mov %_ASM_SI, xen_start_info
mov $init_thread_union+THREAD_SIZE, %_ASM_SP
+#ifdef CONFIG_X86_64
+ /* Set up %gs.
+ *
+ * The base of %gs always points to the bottom of the irqstack
+ * union. If the stack protector canary is enabled, it is
+ * located at %gs:40. Note that, on SMP, the boot cpu uses
+ * init data section till per cpu areas are set up.
+ */
+ movl $MSR_GS_BASE,%ecx
+ movq $INIT_PER_CPU_VAR(irq_stack_union),%rax
+ cdq
+ wrmsr
+#endif
+
jmp xen_start_kernel
END(startup_xen)
__FINIT
--
2.15.1

3
series.conf
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@ -34,6 +34,9 @@ patches.xen/Revert-xen-avoid-deadlock-in-xenbus-driver.patch
patches.xen/Revert-xenbus-remove-transaction-holder-from-list-be.patch
patches.xen/Revert-xen-optimize-xenbus-driver-for-multiple-concu.patch
# Upstream patch for 4.15
patches.xen/x86-xen-init-gs-very-early-to-avoid-page-faults-with.patch
# Hardware-specific fixes, backported from newer kernel and/or developers branches
patches.backports/v2-2-2-Input-synaptics---Lenovo-X1-Carbon-5-should-use-SMBUS-RMI.patch
patches.backports/Input-synaptics---add-Intertouch-support-on-X1-Carbon-6th-and-X280.patch