linux-kernel - [PATCH 4.4 080/266] powerpc/fsl: Flush branch predictor when entering KVM

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Message-Id: <20190515090725.147293414@linuxfoundation.org>
Date:   Wed, 15 May 2019 12:53:07 +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,
        "linuxppc-dev@...abs.org, mpe@...erman.id.au, Diana Craciun" 
        <diana.craciun@....com>, Michael Ellerman <mpe@...erman.id.au>,
        Diana Craciun <diana.craciun@....com>
Subject: [PATCH 4.4 080/266] powerpc/fsl: Flush branch predictor when entering KVM

From: Diana Craciun <diana.craciun@....com>

commit e7aa61f47b23afbec41031bc47ca8d6cb6516abc upstream.

Switching from the guest to host is another place
where the speculative accesses can be exploited.
Flush the branch predictor when entering KVM.

Signed-off-by: Diana Craciun <diana.craciun@....com>
Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 arch/powerpc/kvm/bookehv_interrupts.S |    4 ++++
 1 file changed, 4 insertions(+)

--- a/arch/powerpc/kvm/bookehv_interrupts.S
+++ b/arch/powerpc/kvm/bookehv_interrupts.S
@@ -75,6 +75,10 @@
 	PPC_LL	r1, VCPU_HOST_STACK(r4)
 	PPC_LL	r2, HOST_R2(r1)
 
+START_BTB_FLUSH_SECTION
+	BTB_FLUSH(r10)
+END_BTB_FLUSH_SECTION
+
 	mfspr	r10, SPRN_PID
 	lwz	r8, VCPU_HOST_PID(r4)
 	PPC_LL	r11, VCPU_SHARED(r4)