From: alex.bennee@linaro•org (Alex Bennée)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH v10 15/18] KVM: arm64: Remove eager host SVE state saving
Date: Thu, 24 May 2018 15:54:16 +0100 [thread overview]
Message-ID: <87zi0prtnr.fsf@linaro.org> (raw)
In-Reply-To: <1527005119-6842-16-git-send-email-Dave.Martin@arm.com>
Dave Martin <Dave.Martin@arm•com> writes:
> Now that the host SVE context can be saved on demand from Hyp,
> there is no longer any need to save this state in advance before
> entering the guest.
>
> This patch removes the relevant call to
> kvm_fpsimd_flush_cpu_state().
>
> Since the problem that function was intended to solve now no longer
> exists, the function and its dependencies are also deleted.
>
> Signed-off-by: Dave Martin <Dave.Martin@arm•com>
> Acked-by: Christoffer Dall <christoffer.dall@arm•com>
> Acked-by: Marc Zyngier <marc.zyngier@arm•com>
> Acked-by: Catalin Marinas <catalin.marinas@arm•com>
Reviewed-by: Alex Benn?e <alex.bennee@linaro•org>
> ---
> arch/arm/include/asm/kvm_host.h | 3 ---
> arch/arm64/include/asm/kvm_host.h | 10 ----------
> arch/arm64/kernel/fpsimd.c | 21 ---------------------
> virt/kvm/arm/arm.c | 3 ---
> 4 files changed, 37 deletions(-)
>
> diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
> index 3b85bbb..f079a20 100644
> --- a/arch/arm/include/asm/kvm_host.h
> +++ b/arch/arm/include/asm/kvm_host.h
> @@ -312,9 +312,6 @@ static inline void kvm_arch_vcpu_load_fp(struct kvm_vcpu *vcpu) {}
> static inline void kvm_arch_vcpu_ctxsync_fp(struct kvm_vcpu *vcpu) {}
> static inline void kvm_arch_vcpu_put_fp(struct kvm_vcpu *vcpu) {}
>
> -/* All host FP/SIMD state is restored on guest exit, so nothing to save: */
> -static inline void kvm_fpsimd_flush_cpu_state(void) {}
> -
> static inline void kvm_arm_vhe_guest_enter(void) {}
> static inline void kvm_arm_vhe_guest_exit(void) {}
>
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index 06d5a61..ce7ed92 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -457,16 +457,6 @@ static inline int kvm_arch_vcpu_run_pid_change(struct kvm_vcpu *vcpu)
> }
> #endif
>
> -/*
> - * All host FP/SIMD state is restored on guest exit, so nothing needs
> - * doing here except in the SVE case:
> -*/
> -static inline void kvm_fpsimd_flush_cpu_state(void)
> -{
> - if (system_supports_sve())
> - sve_flush_cpu_state();
> -}
> -
> static inline void kvm_arm_vhe_guest_enter(void)
> {
> local_daif_mask();
> diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
> index f39d3b0..ea5d780 100644
> --- a/arch/arm64/kernel/fpsimd.c
> +++ b/arch/arm64/kernel/fpsimd.c
> @@ -120,7 +120,6 @@
> */
> struct fpsimd_last_state_struct {
> struct user_fpsimd_state *st;
> - bool sve_in_use;
> };
>
> static DEFINE_PER_CPU(struct fpsimd_last_state_struct, fpsimd_last_state);
> @@ -1003,7 +1002,6 @@ void fpsimd_bind_task_to_cpu(void)
> this_cpu_ptr(&fpsimd_last_state);
>
> last->st = ¤t->thread.uw.fpsimd_state;
> - last->sve_in_use = test_thread_flag(TIF_SVE);
> current->thread.fpsimd_cpu = smp_processor_id();
>
> if (system_supports_sve()) {
> @@ -1025,7 +1023,6 @@ void fpsimd_bind_state_to_cpu(struct user_fpsimd_state *st)
> WARN_ON(!in_softirq() && !irqs_disabled());
>
> last->st = st;
> - last->sve_in_use = false;
> }
>
> /*
> @@ -1086,24 +1083,6 @@ void fpsimd_flush_cpu_state(void)
> set_thread_flag(TIF_FOREIGN_FPSTATE);
> }
>
> -/*
> - * Invalidate any task SVE state currently held in this CPU's regs.
> - *
> - * This is used to prevent the kernel from trying to reuse SVE register data
> - * that is detroyed by KVM guest enter/exit. This function should go away when
> - * KVM SVE support is implemented. Don't use it for anything else.
> - */
> -#ifdef CONFIG_ARM64_SVE
> -void sve_flush_cpu_state(void)
> -{
> - struct fpsimd_last_state_struct const *last =
> - this_cpu_ptr(&fpsimd_last_state);
> -
> - if (last->st && last->sve_in_use)
> - fpsimd_flush_cpu_state();
> -}
> -#endif /* CONFIG_ARM64_SVE */
> -
> #ifdef CONFIG_KERNEL_MODE_NEON
>
> DEFINE_PER_CPU(bool, kernel_neon_busy);
> diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
> index ce7c6f3..39e7771 100644
> --- a/virt/kvm/arm/arm.c
> +++ b/virt/kvm/arm/arm.c
> @@ -682,9 +682,6 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
> */
> preempt_disable();
>
> - /* Flush FP/SIMD state that can't survive guest entry/exit */
> - kvm_fpsimd_flush_cpu_state();
> -
> kvm_pmu_flush_hwstate(vcpu);
>
> local_irq_disable();
--
Alex Benn?e
next prev parent reply other threads:[~2018-05-24 14:54 UTC|newest]
Thread overview: 69+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-22 16:05 [PATCH v10 00/18] KVM: arm64: Optimise FPSIMD context switching Dave Martin
2018-05-22 16:05 ` [PATCH v10 01/18] arm64: fpsimd: Fix TIF_FOREIGN_FPSTATE after invalidating cpu regs Dave Martin
2018-05-23 11:33 ` Christoffer Dall
2018-05-23 13:44 ` Alex Bennée
2018-05-23 13:46 ` Catalin Marinas
2018-05-22 16:05 ` [PATCH v10 02/18] thread_info: Add update_thread_flag() helpers Dave Martin
2018-05-23 13:46 ` Alex Bennée
2018-05-23 13:57 ` Dave Martin
2018-05-23 14:35 ` Alex Bennée
2018-05-22 16:05 ` [PATCH v10 03/18] arm64: Use update{,_tsk}_thread_flag() Dave Martin
2018-05-23 13:48 ` Alex Bennée
2018-05-22 16:05 ` [PATCH v10 04/18] KVM: arm/arm64: Introduce kvm_arch_vcpu_run_pid_change Dave Martin
2018-05-23 14:34 ` Alex Bennée
2018-05-23 14:40 ` Dave Martin
2018-05-24 8:11 ` Christoffer Dall
2018-05-24 9:18 ` Alex Bennée
2018-05-24 10:04 ` Dave Martin
2018-05-22 16:05 ` [PATCH v10 05/18] KVM: arm64: Convert lazy FPSIMD context switch trap to C Dave Martin
2018-05-23 19:35 ` Alex Bennée
2018-05-24 8:12 ` Christoffer Dall
2018-05-24 8:54 ` Dave Martin
2018-05-24 9:14 ` Alex Bennée
2018-05-22 16:05 ` [PATCH v10 06/18] arm64: fpsimd: Generalise context saving for non-task contexts Dave Martin
2018-05-23 20:15 ` Alex Bennée
2018-05-24 9:03 ` Dave Martin
2018-05-24 9:41 ` Alex Bennée
2018-05-22 16:05 ` [PATCH v10 07/18] arm64: fpsimd: Eliminate task->mm checks Dave Martin
2018-05-23 11:48 ` Christoffer Dall
2018-05-23 13:31 ` Dave Martin
2018-05-23 14:56 ` Catalin Marinas
2018-05-23 15:03 ` Dave Martin
2018-05-23 16:42 ` Catalin Marinas
2018-05-24 8:33 ` Christoffer Dall
2018-05-24 9:16 ` Alex Bennée
2018-05-24 9:50 ` Dave Martin
2018-05-24 10:06 ` Christoffer Dall
2018-05-24 14:37 ` Dave Martin
2018-05-25 9:00 ` Christoffer Dall
2018-05-25 9:45 ` Dave Martin
2018-05-25 11:28 ` Christoffer Dall
2018-05-24 9:19 ` Alex Bennée
2018-05-22 16:05 ` [PATCH v10 08/18] arm64/sve: Refactor user SVE trap maintenance for external use Dave Martin
2018-05-23 20:16 ` Alex Bennée
2018-05-22 16:05 ` [PATCH v10 09/18] KVM: arm64: Repurpose vcpu_arch.debug_flags for general-purpose flags Dave Martin
2018-05-24 9:21 ` Alex Bennée
2018-05-22 16:05 ` [PATCH v10 10/18] KVM: arm64: Optimise FPSIMD handling to reduce guest/host thrashing Dave Martin
2018-05-24 10:09 ` Alex Bennée
2018-05-24 10:18 ` Dave Martin
2018-05-22 16:05 ` [PATCH v10 11/18] arm64/sve: Move read_zcr_features() out of cpufeature.h Dave Martin
2018-05-24 10:12 ` Alex Bennée
2018-05-22 16:05 ` [PATCH v10 12/18] arm64/sve: Switch sve_pffr() argument from task to thread Dave Martin
2018-05-24 10:12 ` Alex Bennée
2018-05-22 16:05 ` [PATCH v10 13/18] arm64/sve: Move sve_pffr() to fpsimd.h and make inline Dave Martin
2018-05-24 10:20 ` Alex Bennée
2018-05-24 11:22 ` Dave Martin
2018-05-22 16:05 ` [PATCH v10 14/18] KVM: arm64: Save host SVE context as appropriate Dave Martin
2018-05-23 14:59 ` Catalin Marinas
2018-05-24 9:11 ` Christoffer Dall
2018-05-24 14:49 ` Alex Bennée
2018-05-22 16:05 ` [PATCH v10 15/18] KVM: arm64: Remove eager host SVE state saving Dave Martin
2018-05-24 14:54 ` Alex Bennée [this message]
2018-05-22 16:05 ` [PATCH v10 16/18] KVM: arm64: Remove redundant *exit_code changes in fpsimd_guest_exit() Dave Martin
2018-05-24 9:11 ` Christoffer Dall
2018-05-24 15:02 ` Alex Bennée
2018-05-22 16:05 ` [PATCH v10 17/18] KVM: arm64: Fold redundant exit code checks out of fixup_guest_exit() Dave Martin
2018-05-24 9:12 ` Christoffer Dall
2018-05-24 15:06 ` Alex Bennée
2018-05-22 16:05 ` [PATCH v10 18/18] KVM: arm64: Invoke FPSIMD context switch trap from C Dave Martin
2018-05-24 15:09 ` Alex Bennée
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