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079a09a500
Implement hash guest support. Guest entry/exit has to restore and save/clear the SLB, plus several other bits to accommodate hash guests in the P9 path. Radix host, hash guest support is removed from the P7/8 path. The HPT hcalls and faults are not handled in real mode, which is a performance regression. A worst-case fork/exit microbenchmark takes 3x longer after this patch. kbuild benchmark performance is in the noise, but the slowdown is likely to be noticed somewhere. For now, accept this penalty for the benefit of simplifying the P7/8 paths and unifying P9 hash with the new code, because hash is a less important configuration than radix on processors that support it. Hash will benefit from future optimisations to this path, including possibly a faster path to handle such hcalls and interrupts without doing a full exit. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20210528090752.3542186-31-npiggin@gmail.com
Linux kernel
============
There are several guides for kernel developers and users. These guides can
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