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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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2
arch/powerpc/include/asm/opal-api.h
View File

@ -896,6 +896,8 @@ enum {
*/
OPAL_REINIT_CPUS_MMU_HASH = (1 << 2),
OPAL_REINIT_CPUS_MMU_RADIX = (1 << 3),
OPAL_REINIT_CPUS_TM_SUSPEND_DISABLED = (1 << 4),
};
typedef struct oppanel_line {

4
arch/powerpc/include/asm/powernv.h
View File

@ -22,6 +22,8 @@ extern void pnv_npu2_destroy_context(struct npu_context *context,
extern int pnv_npu2_handle_fault(struct npu_context *context, uintptr_t *ea,
unsigned long *flags, unsigned long *status,
int count);
void pnv_tm_init(void);
#else
static inline void powernv_set_nmmu_ptcr(unsigned long ptcr) { }
static inline struct npu_context *pnv_npu2_init_context(struct pci_dev *gpdev,
@ -36,6 +38,8 @@ static inline int pnv_npu2_handle_fault(struct npu_context *context,
unsigned long *status, int count) {
return -ENODEV;
}
static inline void pnv_tm_init(void) { }
#endif
#endif /* _ASM_POWERNV_H */

2
arch/powerpc/include/asm/tm.h
View File

@ -19,4 +19,6 @@ extern void tm_abort(uint8_t cause);
extern void tm_save_sprs(struct thread_struct *thread);
extern void tm_restore_sprs(struct thread_struct *thread);
extern bool tm_suspend_disabled;
#endif /* __ASSEMBLY__ */

7
arch/powerpc/kernel/process.c
View File

@ -77,6 +77,13 @@
extern unsigned long _get_SP(void);
#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
/*
* Are we running in "Suspend disabled" mode? If so we have to block any
* sigreturn that would get us into suspended state, and we also warn in some
* other paths that we should never reach with suspend disabled.
*/
bool tm_suspend_disabled __ro_after_init = false;
static void check_if_tm_restore_required(struct task_struct *tsk)
{
/*

4
arch/powerpc/kernel/prom.c
View File

@ -47,6 +47,7 @@
#include <asm/mmu.h>
#include <asm/paca.h>
#include <asm/pgtable.h>
#include <asm/powernv.h>
#include <asm/iommu.h>
#include <asm/btext.h>
#include <asm/sections.h>
@ -681,7 +682,10 @@ static void __init tm_init(void)
cur_cpu_spec->cpu_user_features2 &=
~(PPC_FEATURE2_HTM_NOSC | PPC_FEATURE2_HTM);
cur_cpu_spec->cpu_features &= ~CPU_FTR_TM;
return;
}
pnv_tm_init();
}
#else
static void tm_init(void) { }

23
arch/powerpc/platforms/powernv/setup.c
View File

@ -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