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Patch "arm: KVM: Allow unaligned accesses at HYP" has been added to the 4.4-stable tree

PATCH [email protected] 1 participant 1 message Jun 12, 2017

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

arm: KVM: Allow unaligned accesses at HYP

to the 4.4-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:
arm-kvm-allow-unaligned-accesses-at-hyp.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From 33b5c38852b29736f3b472dd095c9a18ec22746f Mon Sep 17 00:00:00 2001

From: Marc Zyngier <[email protected]>
Date: Tue, 6 Jun 2017 19:08:35 +0100
Subject: arm: KVM: Allow unaligned accesses at HYP

From: Marc Zyngier <[email protected]>

commit 33b5c38852b29736f3b472dd095c9a18ec22746f upstream.

We currently have the HSCTLR.A bit set, trapping unaligned accesses at HYP, but we're not really prepared to deal with it.

Since the rest of the kernel is pretty happy about that, let's follow its example and set HSCTLR.A to zero. Modern CPUs don't really care.

---
 arch/arm/kvm/init.S |    5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)
arch/arm/kvm/init.S +2 -3
@@ -110,7 +110,6 @@ __do_hyp_init:
 	@  - Write permission implies XN: disabled
 	@  - Instruction cache: enabled
 	@  - Data/Unified cache: enabled
-	@  - Memory alignment checks: enabled
 	@  - MMU: enabled (this code must be run from an identity mapping)
 	mrc	p15, 4, r0, c1, c0, 0	@ HSCR
 	ldr	r2, =HSCTLR_MASK
@@ -118,8 +117,8 @@ __do_hyp_init:
 	mrc	p15, 0, r1, c1, c0, 0	@ SCTLR
 	ldr	r2, =(HSCTLR_EE | HSCTLR_FI | HSCTLR_I | HSCTLR_C)
 	and	r1, r1, r2
- ARM(	ldr	r2, =(HSCTLR_M | HSCTLR_A)			)
- THUMB(	ldr	r2, =(HSCTLR_M | HSCTLR_A | HSCTLR_TE)		)
+ ARM(	ldr	r2, =(HSCTLR_M)					)
+ THUMB(	ldr	r2, =(HSCTLR_M | HSCTLR_TE)			)
 	orr	r1, r1, r2
 	orr	r0, r0, r1
 	isb

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/arm-kvm-allow-unaligned-accesses-at-hyp.patch