On Mon, Feb 08, 2021 at 04:56:16PM +0000, Vincenzo Frascino wrote: > When MTE async mode is enabled TFSR_EL1 contains the accumulative > asynchronous tag check faults for EL1 and EL0. > > During the suspend/resume operations the firmware might perform some > operations that could change the state of the register resulting in > a spurious tag check fault report. > > Save/restore the state of the TFSR_EL1 register during the > suspend/resume operations to prevent this to happen. > > Cc: Catalin Marinas <catalin.mari...@arm.com> > Cc: Will Deacon <w...@kernel.org> > Cc: Lorenzo Pieralisi <lorenzo.pieral...@arm.com> > Signed-off-by: Vincenzo Frascino <vincenzo.frasc...@arm.com> > --- > arch/arm64/include/asm/mte.h | 4 ++++ > arch/arm64/kernel/mte.c | 22 ++++++++++++++++++++++ > arch/arm64/kernel/suspend.c | 3 +++ > 3 files changed, 29 insertions(+) > > diff --git a/arch/arm64/include/asm/mte.h b/arch/arm64/include/asm/mte.h > index 237bb2f7309d..2d79bcaaeb30 100644 > --- a/arch/arm64/include/asm/mte.h > +++ b/arch/arm64/include/asm/mte.h > @@ -43,6 +43,7 @@ void mte_sync_tags(pte_t *ptep, pte_t pte); > void mte_copy_page_tags(void *kto, const void *kfrom); > void flush_mte_state(void); > void mte_thread_switch(struct task_struct *next); > +void mte_suspend_enter(void); > void mte_suspend_exit(void); > long set_mte_ctrl(struct task_struct *task, unsigned long arg); > long get_mte_ctrl(struct task_struct *task); > @@ -68,6 +69,9 @@ static inline void flush_mte_state(void) > static inline void mte_thread_switch(struct task_struct *next) > { > } > +static inline void mte_suspend_enter(void) > +{ > +} > static inline void mte_suspend_exit(void) > { > } > diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c > index 3332aabda466..5c440967721b 100644 > --- a/arch/arm64/kernel/mte.c > +++ b/arch/arm64/kernel/mte.c > @@ -25,6 +25,7 @@ > > u64 gcr_kernel_excl __ro_after_init; > > +static u64 mte_suspend_tfsr_el1;
IIUC you need this per-CPU (core loses context on suspend-to-RAM but also CPUidle, S2R is single threaded but CPUidle runs on every core idle thread). Unless you sync/report it on enter/exit (please note: I am not familiar with MTE so it is just a, perhaps silly, suggestion to avoid saving/restoring it). Lorenzo > static bool report_fault_once = true; > > /* Whether the MTE asynchronous mode is enabled. */ > @@ -295,12 +296,33 @@ void mte_thread_switch(struct task_struct *next) > mte_check_tfsr_el1(); > } > > +void mte_suspend_enter(void) > +{ > + if (!system_supports_mte()) > + return; > + > + /* > + * The barriers are required to guarantee that the indirect writes > + * to TFSR_EL1 are synchronized before we save the state. > + */ > + dsb(nsh); > + isb(); > + > + /* Save SYS_TFSR_EL1 before suspend entry */ > + mte_suspend_tfsr_el1 = read_sysreg_s(SYS_TFSR_EL1); > +} > + > void mte_suspend_exit(void) > { > if (!system_supports_mte()) > return; > > update_gcr_el1_excl(gcr_kernel_excl); > + > + /* Resume SYS_TFSR_EL1 after suspend exit */ > + write_sysreg_s(mte_suspend_tfsr_el1, SYS_TFSR_EL1); > + > + mte_check_tfsr_el1(); > } > > long set_mte_ctrl(struct task_struct *task, unsigned long arg) > diff --git a/arch/arm64/kernel/suspend.c b/arch/arm64/kernel/suspend.c > index a67b37a7a47e..16caa9b32dae 100644 > --- a/arch/arm64/kernel/suspend.c > +++ b/arch/arm64/kernel/suspend.c > @@ -91,6 +91,9 @@ int cpu_suspend(unsigned long arg, int (*fn)(unsigned long)) > unsigned long flags; > struct sleep_stack_data state; > > + /* Report any MTE async fault before going to suspend. */ > + mte_suspend_enter(); > + > /* > * From this point debug exceptions are disabled to prevent > * updates to mdscr register (saved and restored along with > -- > 2.30.0 >