Messages in this thread | | | Subject | Re: [PATCH v2 0/2] powerpc/mm: Conditionally call H_BLOCK_REMOVE | From | "Aneesh Kumar K.V" <> | Date | Tue, 17 Sep 2019 21:42:55 +0530 |
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On 9/16/19 3:25 PM, Laurent Dufour wrote: > Since the commit ba2dd8a26baa ("powerpc/pseries/mm: call H_BLOCK_REMOVE"), > the call to H_BLOCK_REMOVE is always done if the feature is exhibited. > > However, the hypervisor may not support all the block size for the hcall > H_BLOCK_REMOVE depending on the segment base page size and actual page > size. > > When unsupported block size is used, the hcall H_BLOCK_REMOVE is returning > H_PARAM, which is triggering a BUG_ON check leading to a panic like this: > > The PAPR document specifies the TLB Block Invalidate Characteristics which > tells for each couple segment base page size, actual page size, the size of > the block the hcall H_BLOCK_REMOVE is supporting. > > Supporting various block sizes doesn't seem needed at that time since all > systems I was able to play with was supporting an 8 addresses block size, > which is the maximum through the hcall, or none at all. Supporting various > size would complexify the algorithm in call_block_remove() so unless this > is required, this is not done. > > In the case of block size different from 8, a warning message is displayed > at boot time and that block size will be ignored checking for the > H_BLOCK_REMOVE support. > > Due to the minimal amount of hardware showing a limited set of > H_BLOCK_REMOVE supported page size, I don't think there is a need to push > this series to the stable mailing list. > > The first patch is reading the characteristic through the hcall > ibm,get-system-parameter and record the supported block size for each page > size. The second patch is changing the check used to detect the > H_BLOCK_REMOVE availability to take care of the base page size and page > size couple. > > Changes since V1: > > - Remove penc initialisation, this is already done in > mmu_psize_set_default_penc() > - Add details on the TLB Block Invalidate Characteristics's buffer format > - Introduce #define instead of using direct numerical values > - Function reading the characteristics is now directly called from > pSeries_setup_arch() > - The characteristics are now stored in a dedciated table static to lpar.c >
you can use
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
for the series.
-aneesh
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