KVM: PPC: Book3S HV: Handle pending exceptions on guest entry with MSR_EE

[ Upstream commit ecd10702baae5c16a91d139bde7eff84ce55daee ]

Commit 026728dc5d41 ("KVM: PPC: Book3S HV P9: Inject pending xive
interrupts at guest entry") changed guest entry so that if external
interrupts are enabled, BOOK3S_IRQPRIO_EXTERNAL is not tested for. Test
for this regardless of MSR_EE.

For an L1 host, do not inject an interrupt, but always
use LPCR_MER. If the L0 desires it can inject an interrupt.

Fixes: 026728dc5d41 ("KVM: PPC: Book3S HV P9: Inject pending xive interrupts at guest entry")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
[jpn: use kvmpcc_get_msr(), write commit message]
Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231201132618.555031-7-vaibhav@linux.ibm.com
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 11bc5aa..0429488 100644 (file)
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -4663,13 +4663,19 @@ int kvmhv_run_single_vcpu(struct kvm_vcpu *vcpu, u64 time_limit,
 
        if (!nested) {
                kvmppc_core_prepare_to_enter(vcpu);
-               if (__kvmppc_get_msr_hv(vcpu) & MSR_EE) {
-                       if (xive_interrupt_pending(vcpu))
+               if (test_bit(BOOK3S_IRQPRIO_EXTERNAL,
+                            &vcpu->arch.pending_exceptions) ||
+                   xive_interrupt_pending(vcpu)) {
+                       /*
+                        * For nested HV, don't synthesize but always pass MER,
+                        * the L0 will be able to optimise that more
+                        * effectively than manipulating registers directly.
+                        */
+                       if (!kvmhv_on_pseries() && (__kvmppc_get_msr_hv(vcpu) & MSR_EE))
                                kvmppc_inject_interrupt_hv(vcpu,
-                                               BOOK3S_INTERRUPT_EXTERNAL, 0);
-               } else if (test_bit(BOOK3S_IRQPRIO_EXTERNAL,
-                            &vcpu->arch.pending_exceptions)) {
-                       lpcr |= LPCR_MER;
+                                                          BOOK3S_INTERRUPT_EXTERNAL, 0);
+                       else
+                               lpcr |= LPCR_MER;
                }
        } else if (vcpu->arch.pending_exceptions ||
                   vcpu->arch.doorbell_request ||