From 05f2bb0313a2855e491dadfc8319b7da261d7074 Mon Sep 17 00:00:00 2001 From: Paul Mackerras Date: Wed, 7 Feb 2018 19:49:54 +1100 Subject: [PATCH] KVM: PPC: Book3S HV: Fix handling of secondary HPTEG in HPT resizing code 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 Signed-off-by: Paul Mackerras --- 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 966097232d21..d19649960bbf 100644 --- a/arch/powerpc/kvm/book3s_64_mmu_hv.c +++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c @@ -1329,12 +1329,8 @@ 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)); -- 2.30.2