The KVM_PPC_ALLOCATE_HTAB ioctl(), implemented by kvmppc_alloc_reset_hpt()
is supposed to completely clear and reset a guest's Hashed Page Table (HPT)
allocating or re-allocating it if necessary.
In the case where an HPT of the right size already exists and it just
zeroes it, it forces a TLB flush on all guest CPUs, to remove any stale TLB
entries loaded from the old HPT.
However, that situation can arise when the HPT is resizing as well - or
even when switching from an RPT to HPT - so those cases need a TLB flush as
well.
So, move the TLB flush to trigger in all cases except for errors.
Signed-off-by: David Gibson <da...@gibson.dropbear.id.au>
---
arch/powerpc/kvm/book3s_64_mmu_hv.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
Paul, this is based on Paolo's KVM tree, but it should apply without
modification to pretty much any vaguely current tree. It's a pretty
nasty bug - the case we've found hitting it in the wild is a bit
esoteric, but it could in theory affect other situations as well.
Please apply ASAP, and should probably be queued for the stable
branches as well.
diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c
b/arch/powerpc/kvm/book3s_64_mmu_hv.c
index 966097232d21..51a275cc8a4d 100644
--- a/arch/powerpc/kvm/book3s_64_mmu_hv.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c
@@ -159,8 +159,6 @@ long kvmppc_alloc_reset_hpt(struct kvm *kvm, int order)
* Reset all the reverse-mapping chains for all memslots
*/
kvmppc_rmap_reset(kvm);
- /* Ensure that each vcpu will flush its TLB on next entry. */
- cpumask_setall(&kvm->arch.need_tlb_flush);
err = 0;
goto out;
}
@@ -176,6 +174,10 @@ long kvmppc_alloc_reset_hpt(struct kvm *kvm, int order)
kvmppc_set_hpt(kvm, &info);
out:
+ if (err == 0)
+ /* Ensure that each vcpu will flush its TLB on next entry. */
+ cpumask_setall(&kvm->arch.need_tlb_flush);
+
mutex_unlock(&kvm->lock);
return err;
}
--
2.14.3
