KVM: PPC: Disable MSR_FEx for Cell hosts

Cell can't handle MSR_FE0 and MSR_FE1 too well. It gets dog slow.
So let's just override the guest whenever we see one of the two and mask them
out. See commit ddf5f75a16b3e7460ffee881795aa168dffcd0cf for reference.

Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Avi Kivity <avi@redhat.com>

diff --git a/arch/powerpc/kvm/book3s.c b/arch/powerpc/kvm/book3s.c
index ed57584..41c23b6 100644 (file)
--- a/arch/powerpc/kvm/book3s.c
+++ b/arch/powerpc/kvm/book3s.c
@@ -357,6 +357,10 @@ void kvmppc_set_pvr(struct kvm_vcpu *vcpu, u32 pvr)
            !strcmp(cur_cpu_spec->platform, "ppc970"))
                vcpu->arch.hflags |= BOOK3S_HFLAG_DCBZ32;
 
+       /* Cell performs badly if MSR_FEx are set. So let's hope nobody
+          really needs them in a VM on Cell and force disable them. */
+       if (!strcmp(cur_cpu_spec->platform, "ppc-cell-be"))
+               to_book3s(vcpu)->msr_mask &= ~(MSR_FE0 | MSR_FE1);
 }
 
 /* Book3s_32 CPUs always have 32 bytes cache line size, which Linux assumes. To