linux-kernel - [PATCH 4.4 29/90] arm: KVM: Allow unaligned accesses at HYP

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Message-Id: <20170612152557.760936983@linuxfoundation.org>
Date:   Mon, 12 Jun 2017 17:25:35 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Marc Zyngier <marc.zyngier@....com>,
        Christoffer Dall <cdall@...aro.org>
Subject: [PATCH 4.4 29/90] arm: KVM: Allow unaligned accesses at HYP

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Marc Zyngier <marc.zyngier@....com>

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.

Signed-off-by: Marc Zyngier <marc.zyngier@....com>
Signed-off-by: Christoffer Dall <cdall@...aro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/arm/kvm/init.S |    5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

--- a/arch/arm/kvm/init.S
+++ b/arch/arm/kvm/init.S
@@ -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