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Message-Id: <1454522416-6874-18-git-send-email-marc.zyngier@arm.com>
Date:	Wed,  3 Feb 2016 18:00:10 +0000
From:	Marc Zyngier <marc.zyngier@....com>
To:	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will.deacon@....com>,
	Christoffer Dall <christoffer.dall@...aro.org>
Cc:	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	kvm@...r.kernel.org, kvmarm@...ts.cs.columbia.edu
Subject: [PATCH v3 17/23] arm64: KVM: VHE: Add fpsimd enabling on guest access

Despite the fact that a VHE enabled kernel runs at EL2, it uses
CPACR_EL1 to trap FPSIMD access. Add the required alternative
code to re-enable guest FPSIMD access when it has trapped to
EL2.

Reviewed-by: Christoffer Dall <christoffer.dall@...aro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@....com>
---
 arch/arm64/kvm/hyp/entry.S | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/arm64/kvm/hyp/entry.S b/arch/arm64/kvm/hyp/entry.S
index fd0fbe9..ce9e5e5 100644
--- a/arch/arm64/kvm/hyp/entry.S
+++ b/arch/arm64/kvm/hyp/entry.S
@@ -130,9 +130,15 @@ ENDPROC(__guest_exit)
 ENTRY(__fpsimd_guest_restore)
 	stp	x4, lr, [sp, #-16]!
 
+alternative_if_not ARM64_HAS_VIRT_HOST_EXTN
 	mrs	x2, cptr_el2
 	bic	x2, x2, #CPTR_EL2_TFP
 	msr	cptr_el2, x2
+alternative_else
+	mrs	x2, cpacr_el1
+	orr	x2, x2, #CPACR_EL1_FPEN
+	msr	cpacr_el1, x2
+alternative_endif
 	isb
 
 	mrs	x3, tpidr_el2
-- 
2.1.4

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