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KVM: PPC: Book3S HV: Fix handling of secondary HPTEG in HPT resizing code
[ Upstream commit 05f2bb0313
]
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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1 changed files with 2 additions and 6 deletions
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@ -1348,12 +1348,8 @@ static unsigned long resize_hpt_rehash_hpte(struct kvm_resize_hpt *resize,
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}
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new_pteg = hash & new_hash_mask;
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if (vpte & HPTE_V_SECONDARY) {
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BUG_ON(~pteg != (hash & old_hash_mask));
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new_pteg = ~new_pteg;
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} else {
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BUG_ON(pteg != (hash & old_hash_mask));
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}
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if (vpte & HPTE_V_SECONDARY)
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new_pteg = ~hash & new_hash_mask;
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new_idx = new_pteg * HPTES_PER_GROUP + (idx % HPTES_PER_GROUP);
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new_hptep = (__be64 *)(new->virt + (new_idx << 4));
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