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powerpc/powernv: Enable TM without suspend if possible

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Some Power9 revisions can run in a mode where TM operates without
suspended state. If we find ourself on a CPU that might be in this
mode, we query OPAL to check, and if so we reenable TM in CPU
features, and enable a new user feature to signal to userspace that we
are in this mode.

We do not enable the "normal" user feature, PPC_FEATURE2_HTM, but we
do enable PPC_FEATURE2_HTM_NOSC because that indicates to userspace
that the kernel will abort transactions on syscall entry, which is
true regardless of the suspend mode.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Michael Ellerman
2017-10-12 21:17:18 +11:00
parent cba6ac4869
commit 54820530c5
6 changed files with 42 additions and 0 deletions
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23
arch/powerpc/platforms/powernv/setup.c
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@@ -36,6 +36,7 @@
#include <asm/opal.h>
#include <asm/kexec.h>
#include <asm/smp.h>
#include <asm/tm.h>
#include "powernv.h"
@@ -304,6 +305,28 @@ static int __init pnv_probe(void)
return 1;
}
#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
void __init pnv_tm_init(void)
{
if (!firmware_has_feature(FW_FEATURE_OPAL) ||
!pvr_version_is(PVR_POWER9) ||
early_cpu_has_feature(CPU_FTR_TM))
return;
if (opal_reinit_cpus(OPAL_REINIT_CPUS_TM_SUSPEND_DISABLED) != OPAL_SUCCESS)
return;
pr_info("Enabling TM (Transactional Memory) with Suspend Disabled\n");
cur_cpu_spec->cpu_features |= CPU_FTR_TM;
/* Make sure "normal" HTM is off (it should be) */
cur_cpu_spec->cpu_user_features2 &= ~PPC_FEATURE2_HTM;
/* Turn on no suspend mode, and HTM no SC */
cur_cpu_spec->cpu_user_features2 |= PPC_FEATURE2_HTM_NO_SUSPEND | \
PPC_FEATURE2_HTM_NOSC;
tm_suspend_disabled = true;
}
#endif /* CONFIG_PPC_TRANSACTIONAL_MEM */
/*
* Returns the cpu frequency for 'cpu' in Hz. This is used by
* /proc/cpuinfo