From: Paul Mackerras paulus@ozlabs.org
[ Upstream commit 05f2bb0313a2855e491dadfc8319b7da261d7074 ]
This fixes the computation of the HPTE index to use when the HPT resizing code encounters a bolted HPTE which is stored in its secondary HPTE group. The code inverts the HPTE group number, which is correct, but doesn't then mask it with new_hash_mask. As a result, new_pteg will be effectively negative, resulting in new_hptep pointing before the new HPT, which will corrupt memory.
In addition, this removes two BUG_ON statements. The condition that the BUG_ONs were testing -- that we have computed the hash value incorrectly -- has never been observed in testing, and if it did occur, would only affect the guest, not the host. Given that BUG_ON should only be used in conditions where the kernel (i.e. the host kernel, in this case) can't possibly continue execution, it is not appropriate here.
Reviewed-by: David Gibson david@gibson.dropbear.id.au Signed-off-by: Paul Mackerras paulus@ozlabs.org Signed-off-by: Sasha Levin alexander.levin@microsoft.com --- arch/powerpc/kvm/book3s_64_mmu_hv.c | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-)
diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c index b73dbc9e797d..dc0f2ade589e 100644 --- a/arch/powerpc/kvm/book3s_64_mmu_hv.c +++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c @@ -1337,12 +1337,8 @@ static unsigned long resize_hpt_rehash_hpte(struct kvm_resize_hpt *resize, }
new_pteg = hash & new_hash_mask; - if (vpte & HPTE_V_SECONDARY) { - BUG_ON(~pteg != (hash & old_hash_mask)); - new_pteg = ~new_pteg; - } else { - BUG_ON(pteg != (hash & old_hash_mask)); - } + if (vpte & HPTE_V_SECONDARY) + new_pteg = ~hash & new_hash_mask;
new_idx = new_pteg * HPTES_PER_GROUP + (idx % HPTES_PER_GROUP); new_hptep = (__be64 *)(new->virt + (new_idx << 4));