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.ku...@linux.ibm.com> for the series. -aneesh
