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powerpc/book3s64/pkey: Disable pkey on POWER6 and before

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POWER6 only supports AMR update via privileged mode (MSR[PR] = 0,
SPRN_AMR=29) The PR=1 (userspace) alias for that SPR (SPRN_AMR=13) was
only supported from POWER7. Since we don't allow userspace modifying
of AMR value we should disable pkey support on P6 and before.

The hypervisor will still report pkey support via
"ibm,processor-storage-keys". Hence also check for P7 CPU_FTR bit to
decide on pkey support.

Fixes: f491fe3fb4 ("powerpc/book3s64/pkeys: Simplify the key initialization")
Reported-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200726132517.399076-1-aneesh.kumar@linux.ibm.com
This commit is contained in:
Aneesh Kumar K.V 2020-07-26 18:55:17 +05:30 committed by Michael Ellerman
parent 826b07b190
commit 269e829f48
1 changed files with 6 additions and 0 deletions
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6
arch/powerpc/mm/book3s64/pkeys.c
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@ -73,6 +73,12 @@ static int scan_pkey_feature(void)
if (early_radix_enabled())
return 0;
/*
* Only P7 and above supports SPRN_AMR update with MSR[PR] = 1
*/
if (!early_cpu_has_feature(CPU_FTR_ARCH_206))
return 0;
ret = of_scan_flat_dt(dt_scan_storage_keys, &pkeys_total);
if (ret == 0) {
/*