linux-kernel - [PATCH 4.8 089/140] arm64: KVM: VHE: reset PSTATE.PAN on entry to EL2

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Date:   Wed, 26 Oct 2016 14:22:29 +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, Vladimir Murzin <vladimir.murzin@....com>,
        James Morse <james.morse@....com>,
        Marc Zyngier <marc.zyngier@....com>,
        Christoffer Dall <christoffer.dall@...aro.org>
Subject: [PATCH 4.8 089/140] arm64: KVM: VHE: reset PSTATE.PAN on entry to EL2

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

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

From: Vladimir Murzin <vladimir.murzin@....com>

commit cb96408da4e11698674abd04aeac941c1bed2038 upstream.

SCTLR_EL2.SPAN bit controls what happens with the PSTATE.PAN bit on an
exception. However, this bit has no effect on the PSTATE.PAN when
HCR_EL2.E2H or HCR_EL2.TGE is unset. Thus when VHE is used and
exception taken from a guest PSTATE.PAN bit left unchanged and we
continue with a value guest has set.

To address that always reset PSTATE.PAN on entry from EL1.

Fixes: 1f364c8c48a0 ("arm64: VHE: Add support for running Linux in EL2 mode")

Signed-off-by: Vladimir Murzin <vladimir.murzin@....com>
Reviewed-by: James Morse <james.morse@....com>
Acked-by: Marc Zyngier <marc.zyngier@....com>
Signed-off-by: Christoffer Dall <christoffer.dall@...aro.org>
[ rebased for v4.7+ ]
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>


---
 arch/arm64/kvm/hyp/entry.S |    2 ++
 1 file changed, 2 insertions(+)

--- a/arch/arm64/kvm/hyp/entry.S
+++ b/arch/arm64/kvm/hyp/entry.S
@@ -98,6 +98,8 @@ ENTRY(__guest_exit)
 	// x4-x29,lr: vcpu regs
 	// vcpu x0-x3 on the stack
 
+	ALTERNATIVE(nop, SET_PSTATE_PAN(1), ARM64_HAS_PAN, CONFIG_ARM64_PAN)
+
 	add	x2, x0, #VCPU_CONTEXT
 
 	stp	x4, x5,   [x2, #CPU_XREG_OFFSET(4)]