diff options
| author | Mark Brown <broonie@kernel.org> | 2022-04-19 12:22:23 +0100 |
|---|---|---|
| committer | Catalin Marinas <catalin.marinas@arm.com> | 2022-04-22 18:51:02 +0100 |
| commit | 0033cd9339642f9b7bef23f96aa2e7277ab51cce (patch) | |
| tree | f5c437cd6e6c4cd3f0f5a8d7c0e690d5b358f6a2 /arch/arm64/kernel/fpsimd.c | |
| parent | af7167d6d2675f3343eff3ad6c9b4a8e30122e2c (diff) | |
arm64/sme: Implement ZA context switching
Allocate space for storing ZA on first access to SME and use that to save
and restore ZA state when context switching. We do this by using the vector
form of the LDR and STR ZA instructions, these do not require streaming
mode and have implementation recommendations that they avoid contention
issues in shared SMCU implementations.
Since ZA is architecturally guaranteed to be zeroed when enabled we do not
need to explicitly zero ZA, either we will be restoring from a saved copy
or trapping on first use of SME so we know that ZA must be disabled.
Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20220419112247.711548-16-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64/kernel/fpsimd.c')
| -rw-r--r-- | arch/arm64/kernel/fpsimd.c | 20 |
1 files changed, 13 insertions, 7 deletions
diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c index f8506a875eb2..dc38f3f2a28a 100644 --- a/arch/arm64/kernel/fpsimd.c +++ b/arch/arm64/kernel/fpsimd.c @@ -121,6 +121,7 @@ struct fpsimd_last_state_struct { struct user_fpsimd_state *st; void *sve_state; + void *za_state; u64 *svcr; unsigned int sve_vl; unsigned int sme_vl; @@ -387,11 +388,15 @@ static void task_fpsimd_load(void) if (system_supports_sme()) { unsigned long sme_vl = task_get_sme_vl(current); + /* Ensure VL is set up for restoring data */ if (test_thread_flag(TIF_SME)) sme_set_vq(sve_vq_from_vl(sme_vl) - 1); write_sysreg_s(current->thread.svcr, SYS_SVCR_EL0); + if (thread_za_enabled(¤t->thread)) + za_load_state(current->thread.za_state); + if (thread_sm_enabled(¤t->thread)) { restore_sve_regs = true; restore_ffr = system_supports_fa64(); @@ -441,11 +446,10 @@ static void fpsimd_save(void) u64 *svcr = last->svcr; *svcr = read_sysreg_s(SYS_SVCR_EL0); - if (thread_za_enabled(¤t->thread)) { - /* ZA state managment is not implemented yet */ - force_signal_inject(SIGKILL, SI_KERNEL, 0, 0); - return; - } + *svcr = read_sysreg_s(SYS_SVCR_EL0); + + if (*svcr & SYS_SVCR_EL0_ZA_MASK) + za_save_state(last->za_state); /* If we are in streaming mode override regular SVE. */ if (*svcr & SYS_SVCR_EL0_SM_MASK) { @@ -1483,6 +1487,7 @@ static void fpsimd_bind_task_to_cpu(void) WARN_ON(!system_supports_fpsimd()); last->st = ¤t->thread.uw.fpsimd_state; last->sve_state = current->thread.sve_state; + last->za_state = current->thread.za_state; last->sve_vl = task_get_sve_vl(current); last->sme_vl = task_get_sme_vl(current); last->svcr = ¤t->thread.svcr; @@ -1500,8 +1505,8 @@ static void fpsimd_bind_task_to_cpu(void) } void fpsimd_bind_state_to_cpu(struct user_fpsimd_state *st, void *sve_state, - unsigned int sve_vl, unsigned int sme_vl, - u64 *svcr) + unsigned int sve_vl, void *za_state, + unsigned int sme_vl, u64 *svcr) { struct fpsimd_last_state_struct *last = this_cpu_ptr(&fpsimd_last_state); @@ -1512,6 +1517,7 @@ void fpsimd_bind_state_to_cpu(struct user_fpsimd_state *st, void *sve_state, last->st = st; last->svcr = svcr; last->sve_state = sve_state; + last->za_state = za_state; last->sve_vl = sve_vl; last->sme_vl = sme_vl; } |