linux-kernel - [PATCH 5.12 126/677] KVM: arm64: Fully zero the vcpu state on reset

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Message-Id: <20210512144841.400695015@linuxfoundation.org>
Date:   Wed, 12 May 2021 16:42:52 +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, Marc Zyngier <maz@...nel.org>
Subject: [PATCH 5.12 126/677] KVM: arm64: Fully zero the vcpu state on reset

From: Marc Zyngier <maz@...nel.org>

commit 85d703746154cdc6794b6654b587b0b0354c97e9 upstream.

On vcpu reset, we expect all the registers to be brought back
to their initial state, which happens to be a bunch of zeroes.

However, some recent commit broke this, and is now leaving a bunch
of registers (such as the FP state) with whatever was left by the
guest. My bad.

Zero the reset of the state (32bit SPSRs and FPSIMD state).

Cc: stable@...r.kernel.org
Fixes: e47c2055c68e ("KVM: arm64: Make struct kvm_regs userspace-only")
Signed-off-by: Marc Zyngier <maz@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 arch/arm64/kvm/reset.c |    5 +++++
 1 file changed, 5 insertions(+)

--- a/arch/arm64/kvm/reset.c
+++ b/arch/arm64/kvm/reset.c
@@ -242,6 +242,11 @@ int kvm_reset_vcpu(struct kvm_vcpu *vcpu
 
 	/* Reset core registers */
 	memset(vcpu_gp_regs(vcpu), 0, sizeof(*vcpu_gp_regs(vcpu)));
+	memset(&vcpu->arch.ctxt.fp_regs, 0, sizeof(vcpu->arch.ctxt.fp_regs));
+	vcpu->arch.ctxt.spsr_abt = 0;
+	vcpu->arch.ctxt.spsr_und = 0;
+	vcpu->arch.ctxt.spsr_irq = 0;
+	vcpu->arch.ctxt.spsr_fiq = 0;
 	vcpu_gp_regs(vcpu)->pstate = pstate;
 
 	/* Reset system registers */