Subject: [PATCH v2 05/37] KVM: PPC: Book3S HV: Ensure MSR[ME] is always set in guest MSR

From: Nicholas Piggin <[email-masked]>
Date: Thu, 25 Feb 2021 23:46:20 +1000

Rather than add the ME bit to the MSR when the guest is entered, make
it clear that the hypervisor does not allow the guest to clear the bit.

The ME addition is kept in the code for now, but a future patch will
warn if it's not present.

Reviewed-by: Fabiano Rosas <[email-masked]>
Signed-off-by: Nicholas Piggin <[email-masked]>
---
 arch/powerpc/kvm/book3s_hv_builtin.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/powerpc/kvm/book3s_hv_builtin.c b/arch/powerpc/kvm/book3s_hv_builtin.c
index 158d309b42a3..1ca484160636 100644
--- a/arch/powerpc/kvm/book3s_hv_builtin.c
+++ b/arch/powerpc/kvm/book3s_hv_builtin.c
@@ -662,6 +662,13 @@ static void kvmppc_end_cede(struct kvm_vcpu *vcpu)
 
 void kvmppc_set_msr_hv(struct kvm_vcpu *vcpu, u64 msr)
 {
+	/*
+	 * Guest must always run with machine check interrupt
+	 * enabled.
+	 */
+	if (!(msr & MSR_ME))
+		msr |= MSR_ME;
+
 	/*
 	 * Check for illegal transactional state bit combination
 	 * and if we find it, force the TS field to a safe state.
-- 
2.23.0