| Message ID | 20190423135719.11306-3-julien.grall@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arm64/fpsimd: Don't disable softirq when touching FPSIMD/SVE state | expand |
On Tue, Apr 23, 2019 at 02:57:18PM +0100, Julien Grall wrote: > tent-Length: 4295 > Lines: 128 > > The only external user of fpsimd_save() and fpsimd_flush_cpu_state() is > the KVM FPSIMD code. > > A following patch will introduce a mechanism to acquire owernship of the > FPSIMD/SVE context for performing context management operations. Rather > than having to export the new helpers to get/put the context, we can just > introduce a new function to combine fpsimd_save() and > fpsimd_flush_cpu_state(). > > This has also the advantage to remove any external call of fpsimd_save() > and fpsimd_flush_cpu_state(), so they can be turned static. > > Lastly, the new function can also be used in the PM notifier. > > Signed-off-by: Julien Grall <julien.grall@arm.com> > > --- > kernel_neon_begin() does not use fpsimd_save_and_flush_cpu_state() > because the next patch will modify the function to also grab the > FPSIMD/SVE context. > > Changes in v3: > - Rework the commit message > - Move the prototype of fpsimd_save_and_flush_cpu_state() > further down in the header > - Remove comment in kvm_arch_vcpu_put_fp() > > Changes in v2: > - Patch added > --- > arch/arm64/include/asm/fpsimd.h | 5 ++--- > arch/arm64/kernel/fpsimd.c | 17 +++++++++++++---- > arch/arm64/kvm/fpsimd.c | 4 +--- > 3 files changed, 16 insertions(+), 10 deletions(-) > > diff --git a/arch/arm64/include/asm/fpsimd.h b/arch/arm64/include/asm/fpsimd.h > index b73d12fcc7f9..c311d36ecffe 100644 > --- a/arch/arm64/include/asm/fpsimd.h > +++ b/arch/arm64/include/asm/fpsimd.h > @@ -48,8 +48,6 @@ struct task_struct; > extern void fpsimd_save_state(struct user_fpsimd_state *state); > extern void fpsimd_load_state(struct user_fpsimd_state *state); > > -extern void fpsimd_save(void); > - > extern void fpsimd_thread_switch(struct task_struct *next); > extern void fpsimd_flush_thread(void); > > @@ -63,7 +61,8 @@ extern void fpsimd_bind_state_to_cpu(struct user_fpsimd_state *state, > void *sve_state, unsigned int sve_vl); > > extern void fpsimd_flush_task_state(struct task_struct *target); > -extern void fpsimd_flush_cpu_state(void); > + > +extern void fpsimd_save_and_flush_cpu_state(void); Nit: You could drop this blank line: these are all "state maintenance" operations, roughly speaking. But don't bother unless you respin for some other reason. [...] With or without that, Reviewed-by: Dave Martin <Dave.Martin@arm.com> Cheers ---Dave
Hi Dave, On 24/04/2019 14:17, Dave Martin wrote: > On Tue, Apr 23, 2019 at 02:57:18PM +0100, Julien Grall wrote: >> tent-Length: 4295 >> Lines: 128 >> >> The only external user of fpsimd_save() and fpsimd_flush_cpu_state() is >> the KVM FPSIMD code. >> >> A following patch will introduce a mechanism to acquire owernship of the >> FPSIMD/SVE context for performing context management operations. Rather >> than having to export the new helpers to get/put the context, we can just >> introduce a new function to combine fpsimd_save() and >> fpsimd_flush_cpu_state(). >> >> This has also the advantage to remove any external call of fpsimd_save() >> and fpsimd_flush_cpu_state(), so they can be turned static. >> >> Lastly, the new function can also be used in the PM notifier. >> >> Signed-off-by: Julien Grall <julien.grall@arm.com> >> >> --- >> kernel_neon_begin() does not use fpsimd_save_and_flush_cpu_state() >> because the next patch will modify the function to also grab the >> FPSIMD/SVE context. >> >> Changes in v3: >> - Rework the commit message >> - Move the prototype of fpsimd_save_and_flush_cpu_state() >> further down in the header >> - Remove comment in kvm_arch_vcpu_put_fp() >> >> Changes in v2: >> - Patch added >> --- >> arch/arm64/include/asm/fpsimd.h | 5 ++--- >> arch/arm64/kernel/fpsimd.c | 17 +++++++++++++---- >> arch/arm64/kvm/fpsimd.c | 4 +--- >> 3 files changed, 16 insertions(+), 10 deletions(-) >> >> diff --git a/arch/arm64/include/asm/fpsimd.h b/arch/arm64/include/asm/fpsimd.h >> index b73d12fcc7f9..c311d36ecffe 100644 >> --- a/arch/arm64/include/asm/fpsimd.h >> +++ b/arch/arm64/include/asm/fpsimd.h >> @@ -48,8 +48,6 @@ struct task_struct; >> extern void fpsimd_save_state(struct user_fpsimd_state *state); >> extern void fpsimd_load_state(struct user_fpsimd_state *state); >> >> -extern void fpsimd_save(void); >> - >> extern void fpsimd_thread_switch(struct task_struct *next); >> extern void fpsimd_flush_thread(void); >> >> @@ -63,7 +61,8 @@ extern void fpsimd_bind_state_to_cpu(struct user_fpsimd_state *state, >> void *sve_state, unsigned int sve_vl); >> >> extern void fpsimd_flush_task_state(struct task_struct *target); >> -extern void fpsimd_flush_cpu_state(void); >> + >> +extern void fpsimd_save_and_flush_cpu_state(void); > > Nit: You could drop this blank line: these are all "state maintenance" > operations, roughly speaking. > > But don't bother unless you respin for some other reason. It looks like I will need to make some changes in patch #3. So I will remove the line at the same time. > > [...] > > With or without that, > > Reviewed-by: Dave Martin <Dave.Martin@arm.com> Thank you! Cheers,
On Thu, Apr 25, 2019 at 01:37:40PM +0100, Julien Grall wrote: > Hi Dave, > > On 24/04/2019 14:17, Dave Martin wrote: > >On Tue, Apr 23, 2019 at 02:57:18PM +0100, Julien Grall wrote: > >>tent-Length: 4295 > >>Lines: 128 > >> > >>The only external user of fpsimd_save() and fpsimd_flush_cpu_state() is > >>the KVM FPSIMD code. > >> > >>A following patch will introduce a mechanism to acquire owernship of the > >>FPSIMD/SVE context for performing context management operations. Rather > >>than having to export the new helpers to get/put the context, we can just > >>introduce a new function to combine fpsimd_save() and > >>fpsimd_flush_cpu_state(). > >> > >>This has also the advantage to remove any external call of fpsimd_save() > >>and fpsimd_flush_cpu_state(), so they can be turned static. > >> > >>Lastly, the new function can also be used in the PM notifier. > >> > >>Signed-off-by: Julien Grall <julien.grall@arm.com> > >> > >>--- > >> kernel_neon_begin() does not use fpsimd_save_and_flush_cpu_state() > >> because the next patch will modify the function to also grab the > >> FPSIMD/SVE context. > >> > >> Changes in v3: > >> - Rework the commit message > >> - Move the prototype of fpsimd_save_and_flush_cpu_state() > >> further down in the header > >> - Remove comment in kvm_arch_vcpu_put_fp() > >> > >> Changes in v2: > >> - Patch added > >>--- > >> arch/arm64/include/asm/fpsimd.h | 5 ++--- > >> arch/arm64/kernel/fpsimd.c | 17 +++++++++++++---- > >> arch/arm64/kvm/fpsimd.c | 4 +--- > >> 3 files changed, 16 insertions(+), 10 deletions(-) > >> > >>diff --git a/arch/arm64/include/asm/fpsimd.h b/arch/arm64/include/asm/fpsimd.h > >>index b73d12fcc7f9..c311d36ecffe 100644 > >>--- a/arch/arm64/include/asm/fpsimd.h > >>+++ b/arch/arm64/include/asm/fpsimd.h > >>@@ -48,8 +48,6 @@ struct task_struct; > >> extern void fpsimd_save_state(struct user_fpsimd_state *state); > >> extern void fpsimd_load_state(struct user_fpsimd_state *state); > >>-extern void fpsimd_save(void); > >>- > >> extern void fpsimd_thread_switch(struct task_struct *next); > >> extern void fpsimd_flush_thread(void); > >>@@ -63,7 +61,8 @@ extern void fpsimd_bind_state_to_cpu(struct user_fpsimd_state *state, > >> void *sve_state, unsigned int sve_vl); > >> extern void fpsimd_flush_task_state(struct task_struct *target); > >>-extern void fpsimd_flush_cpu_state(void); > >>+ > >>+extern void fpsimd_save_and_flush_cpu_state(void); > > > >Nit: You could drop this blank line: these are all "state maintenance" > >operations, roughly speaking. > > > >But don't bother unless you respin for some other reason. > > It looks like I will need to make some changes in patch #3. So I will remove > the line at the same time. OK, fair enough. Cheers ---Dave
diff --git a/arch/arm64/include/asm/fpsimd.h b/arch/arm64/include/asm/fpsimd.h index b73d12fcc7f9..c311d36ecffe 100644 --- a/arch/arm64/include/asm/fpsimd.h +++ b/arch/arm64/include/asm/fpsimd.h @@ -48,8 +48,6 @@ struct task_struct; extern void fpsimd_save_state(struct user_fpsimd_state *state); extern void fpsimd_load_state(struct user_fpsimd_state *state); -extern void fpsimd_save(void); - extern void fpsimd_thread_switch(struct task_struct *next); extern void fpsimd_flush_thread(void); @@ -63,7 +61,8 @@ extern void fpsimd_bind_state_to_cpu(struct user_fpsimd_state *state, void *sve_state, unsigned int sve_vl); extern void fpsimd_flush_task_state(struct task_struct *target); -extern void fpsimd_flush_cpu_state(void); + +extern void fpsimd_save_and_flush_cpu_state(void); /* Maximum VL that SVE VL-agnostic software can transparently support */ #define SVE_VL_ARCH_MAX 0x100 diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c index 56afa40263d9..5313aa257be6 100644 --- a/arch/arm64/kernel/fpsimd.c +++ b/arch/arm64/kernel/fpsimd.c @@ -246,7 +246,7 @@ static void task_fpsimd_load(void) * * Softirqs (and preemption) must be disabled. */ -void fpsimd_save(void) +static void fpsimd_save(void) { struct fpsimd_last_state_struct const *last = this_cpu_ptr(&fpsimd_last_state); @@ -1122,12 +1122,22 @@ void fpsimd_flush_task_state(struct task_struct *t) * Invalidate any task's FPSIMD state that is present on this cpu. * This function must be called with softirqs disabled. */ -void fpsimd_flush_cpu_state(void) +static void fpsimd_flush_cpu_state(void) { __this_cpu_write(fpsimd_last_state.st, NULL); set_thread_flag(TIF_FOREIGN_FPSTATE); } +/* + * Save the FPSIMD state to memory and invalidate cpu view. + * This function must be called with softirqs (and preemption) disabled. + */ +void fpsimd_save_and_flush_cpu_state(void) +{ + fpsimd_save(); + fpsimd_flush_cpu_state(); +} + #ifdef CONFIG_KERNEL_MODE_NEON DEFINE_PER_CPU(bool, kernel_neon_busy); @@ -1284,8 +1294,7 @@ static int fpsimd_cpu_pm_notifier(struct notifier_block *self, { switch (cmd) { case CPU_PM_ENTER: - fpsimd_save(); - fpsimd_flush_cpu_state(); + fpsimd_save_and_flush_cpu_state(); break; case CPU_PM_EXIT: break; diff --git a/arch/arm64/kvm/fpsimd.c b/arch/arm64/kvm/fpsimd.c index 6e3c9c8b2df9..525010504f9d 100644 --- a/arch/arm64/kvm/fpsimd.c +++ b/arch/arm64/kvm/fpsimd.c @@ -112,9 +112,7 @@ void kvm_arch_vcpu_put_fp(struct kvm_vcpu *vcpu) if (vcpu->arch.flags & KVM_ARM64_FP_ENABLED) { u64 *guest_zcr = &vcpu->arch.ctxt.sys_regs[ZCR_EL1]; - /* Clean guest FP state to memory and invalidate cpu view */ - fpsimd_save(); - fpsimd_flush_cpu_state(); + fpsimd_save_and_flush_cpu_state(); if (guest_has_sve) *guest_zcr = read_sysreg_s(SYS_ZCR_EL12);
The only external user of fpsimd_save() and fpsimd_flush_cpu_state() is the KVM FPSIMD code. A following patch will introduce a mechanism to acquire owernship of the FPSIMD/SVE context for performing context management operations. Rather than having to export the new helpers to get/put the context, we can just introduce a new function to combine fpsimd_save() and fpsimd_flush_cpu_state(). This has also the advantage to remove any external call of fpsimd_save() and fpsimd_flush_cpu_state(), so they can be turned static. Lastly, the new function can also be used in the PM notifier. Signed-off-by: Julien Grall <julien.grall@arm.com> --- kernel_neon_begin() does not use fpsimd_save_and_flush_cpu_state() because the next patch will modify the function to also grab the FPSIMD/SVE context. Changes in v3: - Rework the commit message - Move the prototype of fpsimd_save_and_flush_cpu_state() further down in the header - Remove comment in kvm_arch_vcpu_put_fp() Changes in v2: - Patch added --- arch/arm64/include/asm/fpsimd.h | 5 ++--- arch/arm64/kernel/fpsimd.c | 17 +++++++++++++---- arch/arm64/kvm/fpsimd.c | 4 +--- 3 files changed, 16 insertions(+), 10 deletions(-)