On Thu, 30 Sep 2021 19:11:29 +0100 Mark Brown <broonie@xxxxxxxxxx> wrote: > 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@xxxxxxxxxx> sme_alloc() forwards definition should be in the next patch. > --- > arch/arm64/include/asm/fpsimd.h | 5 ++++- > arch/arm64/include/asm/fpsimdmacros.h | 22 ++++++++++++++++++++++ > arch/arm64/include/asm/processor.h | 1 + > arch/arm64/kernel/entry-fpsimd.S | 22 ++++++++++++++++++++++ > arch/arm64/kernel/fpsimd.c | 16 ++++++++++------ > arch/arm64/kvm/fpsimd.c | 2 +- > 6 files changed, 60 insertions(+), 8 deletions(-) > > diff --git a/arch/arm64/include/asm/fpsimd.h b/arch/arm64/include/asm/fpsimd.h > index 43737ca91f1a..45f7153067bb 100644 > --- a/arch/arm64/include/asm/fpsimd.h > +++ b/arch/arm64/include/asm/fpsimd.h > @@ -47,7 +47,7 @@ extern void fpsimd_update_current_state(struct user_fpsimd_state const *state); > > extern void fpsimd_bind_state_to_cpu(struct user_fpsimd_state *state, > void *sve_state, unsigned int sve_vl, > - unsigned int sme_vl); > + void *za_state, unsigned int sme_vl); > > extern void fpsimd_flush_task_state(struct task_struct *target); > extern void fpsimd_save_and_flush_cpu_state(void); > @@ -90,6 +90,8 @@ extern void sve_flush_live(bool flush_ffr, unsigned long vq_minus_1); > extern unsigned int sve_get_vl(void); > extern void sve_set_vq(unsigned long vq_minus_1); > extern void sme_set_vq(unsigned long vq_minus_1); > +extern void sme_save_state(void *state, unsigned int vq_minus_1); > +extern void sme_load_state(void const *state, unsigned int vq_minus_1); > > struct arm64_cpu_capabilities; > extern void sve_kernel_enable(const struct arm64_cpu_capabilities *__unused); > @@ -119,6 +121,7 @@ static inline unsigned int __bit_to_vq(unsigned int bit) > extern size_t sve_state_size(struct task_struct const *task); > > extern void sve_alloc(struct task_struct *task); > +extern void sme_alloc(struct task_struct *task); Should be in the next patch where this function is introduced. > extern void fpsimd_release_task(struct task_struct *task); > extern void fpsimd_sync_to_sve(struct task_struct *task); > extern void sve_sync_to_fpsimd(struct task_struct *task);
