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authorPaul Mackerras <paulus@ozlabs.org>2018-02-07 19:49:54 +1100
committerPaul Mackerras <paulus@ozlabs.org>2018-02-09 15:35:24 +1100
commit05f2bb0313a2855e491dadfc8319b7da261d7074 (patch)
tree5e75fbfcc885ae5235eaaef4ef2ef310160ab56d
parent57ea5f161a7de5b1913c212d04f57a175b159fdf (diff)
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 <david@gibson.dropbear.id.au> Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
-rw-r--r--arch/powerpc/kvm/book3s_64_mmu_hv.c8
1 files 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));

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