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arm64: KVM: Allow unaligned accesses at EL2 

We currently have the SCTLR_EL2.A bit set, trapping unaligned accesses
at EL2, but we're not really prepared to deal with it. So far, this
has been unnoticed, until GCC 7 started emitting those (in particular
64bit writes on a 32bit boundary).

Since the rest of the kernel is pretty happy about that, let's follow
its example and set SCTLR_EL2.A to zero. Modern CPUs don't really
care.

Cc: stable@vger.kernel.org
Reported-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <cdall@linaro.org>
This commit is contained in:
Marc Zyngier 2017-06-06 19:08:34 +01:00 committed by Christoffer Dall
parent d68c1f7fd1
commit 78fd6dcf11
1 changed files with 3 additions and 2 deletions
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5
arch/arm64/kvm/hyp-init.S
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@ -108,9 +108,10 @@ __do_hyp_init:
/*
* Preserve all the RES1 bits while setting the default flags,
* as well as the EE bit on BE.
* as well as the EE bit on BE. Drop the A flag since the compiler
* is allowed to generate unaligned accesses.
*/
ldr x4, =(SCTLR_EL2_RES1 | SCTLR_ELx_FLAGS)
ldr x4, =(SCTLR_EL2_RES1 | (SCTLR_ELx_FLAGS & ~SCTLR_ELx_A))
CPU_BE( orr x4, x4, #SCTLR_ELx_EE)
msr sctlr_el2, x4
isb