linux-kernel - [PATCH 1/1] KVM: inject data abort if instruction cannot be decoded

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Message-Id: <20190904180736.29009-1-xypron.glpk@gmx.de>
Date:   Wed,  4 Sep 2019 20:07:36 +0200
From:   Heinrich Schuchardt <xypron.glpk@....de>
To:     Marc Zyngier <marc.zyngier@....com>
Cc:     James Morse <james.morse@....com>,
        Julien Thierry <julien.thierry@....com>,
        Suzuki K Pouloze <suzuki.poulose@....com>,
        Peter Maydell <peter.maydell@...aro.org>,
        Stefan Hajnoczi <stefanha@...hat.com>,
        Daniel P . Berrangé <berrange@...hat.com>,
        linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
        linux-kernel@...r.kernel.org,
        Heinrich Schuchardt <xypron.glpk@....de>
Subject: [PATCH 1/1] KVM: inject data abort if instruction cannot be decoded

If an application tries to access memory that is not mapped, an error
ENOSYS, "load/store instruction decoding not implemented" may occur.
QEMU will hang with a register dump.

Instead create a data abort that can be handled gracefully by the
application running in the virtual environment.

Now the virtual machine can react to the event in the most appropriate
way - by recovering, by writing an informative log, or by rebooting.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@....de>
---
 virt/kvm/arm/mmio.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/virt/kvm/arm/mmio.c b/virt/kvm/arm/mmio.c
index a8a6a0c883f1..0cbed7d6a0f4 100644
--- a/virt/kvm/arm/mmio.c
+++ b/virt/kvm/arm/mmio.c
@@ -161,8 +161,8 @@ int io_mem_abort(struct kvm_vcpu *vcpu, struct kvm_run *run,
 		if (ret)
 			return ret;
 	} else {
-		kvm_err("load/store instruction decoding not implemented\n");
-		return -ENOSYS;
+		kvm_inject_dabt(vcpu, kvm_vcpu_get_hfar(vcpu));
+		return 1;
 	}

 	rt = vcpu->arch.mmio_decode.rt;
--
2.23.0.rc1