powerpc/vas: Don't set uses_vas for kernel windows
cp_abort is only required for user windows, because kernel context
must not be preempted between a copy/paste pair.
Without this patch, the init task gets used_vas set when it runs the
nx842_powernv_init initcall, which opens windows for kernel usage.
used_vas is then never cleared anywhere, so it gets propagated into
all other tasks. It's a property of the address space, so it should
really be cleared when a new mm is created (or in dup_mmap if the
mmaps are marked as VM_DONTCOPY). For now we seem to have no such
driver, so leave that for another patch.
Fixes: 6c8e6bb2a5
("powerpc/vas: Add support for user receive window")
Cc: stable@vger.kernel.org # v4.15+
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
parent
c9dccf1d07
commit
b00b628986
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@ -1063,16 +1063,16 @@ struct vas_window *vas_tx_win_open(int vasid, enum vas_cop_type cop,
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rc = PTR_ERR(txwin->paste_kaddr);
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goto free_window;
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}
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} else {
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/*
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* A user mapping must ensure that context switch issues
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* CP_ABORT for this thread.
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*/
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rc = set_thread_uses_vas();
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if (rc)
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goto free_window;
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}
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/*
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* Now that we have a send window, ensure context switch issues
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* CP_ABORT for this thread.
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*/
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rc = -EINVAL;
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if (set_thread_uses_vas() < 0)
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goto free_window;
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set_vinst_win(vinst, txwin);
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return txwin;
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