From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoffer Dall Subject: Re: [PATCH v6 6/6] arm/arm64: KVM: Enable armv8 fp/simd enhanced context switch Date: Sun, 10 Jan 2016 17:32:23 +0100 Message-ID: <20160110163223.GH30867@cbox> References: <1451167016-3787-1-git-send-email-m.smarduch@samsung.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: kvmarm@lists.cs.columbia.edu, marc.zyngier@arm.com, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org To: Mario Smarduch Return-path: Received: from mail-wm0-f50.google.com ([74.125.82.50]:35863 "EHLO mail-wm0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757246AbcAJQbp (ORCPT ); Sun, 10 Jan 2016 11:31:45 -0500 Received: by mail-wm0-f50.google.com with SMTP id l65so185574887wmf.1 for ; Sun, 10 Jan 2016 08:31:45 -0800 (PST) Content-Disposition: inline In-Reply-To: <1451167016-3787-1-git-send-email-m.smarduch@samsung.com> Sender: kvm-owner@vger.kernel.org List-ID: On Sat, Dec 26, 2015 at 01:56:56PM -0800, Mario Smarduch wrote: > Enable armv8 enhanced fp/simd context switch. Guest and host registers are only > context switched on first access and vcpu put. > > Signed-off-by: Mario Smarduch > --- > arch/arm/kvm/arm.c | 13 +++++++++++-- > arch/arm64/kernel/asm-offsets.c | 1 + > arch/arm64/kvm/hyp/entry.S | 1 + > arch/arm64/kvm/hyp/switch.c | 26 ++------------------------ > 4 files changed, 15 insertions(+), 26 deletions(-) > > diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c > index b16ed98..633a208 100644 > --- a/arch/arm/kvm/arm.c > +++ b/arch/arm/kvm/arm.c > @@ -316,10 +316,19 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu) > void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu) > { > /* If the fp/simd registers are dirty save guest, restore host. */ > - if (vcpu_vfp_isdirty(vcpu)) > + if (vcpu_vfp_isdirty(vcpu)) { > + > vcpu_restore_host_vfp_state(vcpu); > > - /* Restore host FPEXC trashed in vcpu_load */ > + /* > + * For 32bit guest on arm64 save the guest fpexc register > + * in EL2 mode. > + */ > + if (vcpu_guest_is_32bit(vcpu)) > + vcpu_save_fpexc(vcpu); > + } > + > + /* For arm32 restore host FPEXC trashed in vcpu_load. */ > vcpu_restore_host_fpexc(vcpu); > > /* > diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c > index 94090a6..d69145c 100644 > --- a/arch/arm64/kernel/asm-offsets.c > +++ b/arch/arm64/kernel/asm-offsets.c > @@ -112,6 +112,7 @@ int main(void) > DEFINE(VCPU_ESR_EL2, offsetof(struct kvm_vcpu, arch.fault.esr_el2)); > DEFINE(VCPU_FAR_EL2, offsetof(struct kvm_vcpu, arch.fault.far_el2)); > DEFINE(VCPU_HPFAR_EL2, offsetof(struct kvm_vcpu, arch.fault.hpfar_el2)); > + DEFINE(VCPU_CPTR_EL2, offsetof(struct kvm_vcpu, arch.cptr_el2)); > DEFINE(VCPU_HOST_CONTEXT, offsetof(struct kvm_vcpu, arch.host_cpu_context)); > #endif > #ifdef CONFIG_CPU_PM > diff --git a/arch/arm64/kvm/hyp/entry.S b/arch/arm64/kvm/hyp/entry.S > index fd0fbe9..ce7e903 100644 > --- a/arch/arm64/kvm/hyp/entry.S > +++ b/arch/arm64/kvm/hyp/entry.S > @@ -136,6 +136,7 @@ ENTRY(__fpsimd_guest_restore) > isb > > mrs x3, tpidr_el2 > + str w2, [x3, #VCPU_CPTR_EL2] I'm confused here, why do we need to do this now and not in the previous patch? Maybe it helps if we merge these last two patches into one. > > ldr x0, [x3, #VCPU_HOST_CONTEXT] > kern_hyp_va x0 > diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c > index ca8f5a5..962d179 100644 > --- a/arch/arm64/kvm/hyp/switch.c > +++ b/arch/arm64/kvm/hyp/switch.c > @@ -19,24 +19,10 @@ > > static void __hyp_text __activate_traps(struct kvm_vcpu *vcpu) > { > - u64 val; > - > - /* > - * We are about to set CPTR_EL2.TFP to trap all floating point > - * register accesses to EL2, however, the ARM ARM clearly states that > - * traps are only taken to EL2 if the operation would not otherwise > - * trap to EL1. Therefore, always make sure that for 32-bit guests, > - * we set FPEXC.EN to prevent traps to EL1, when setting the TFP bit. > - */ > - val = vcpu->arch.hcr_el2; > - if (!(val & HCR_RW)) { > - write_sysreg(1 << 30, fpexc32_el2); > - isb(); > - } > - write_sysreg(val, hcr_el2); > + write_sysreg(vcpu->arch.hcr_el2, hcr_el2); > /* Trap on AArch32 cp15 c15 accesses (EL1 or EL0) */ > write_sysreg(1 << 15, hstr_el2); > - write_sysreg(CPTR_EL2_TTA | CPTR_EL2_TFP, cptr_el2); > + write_sysreg(vcpu->arch.cptr_el2, cptr_el2); > write_sysreg(vcpu->arch.mdcr_el2, mdcr_el2); > } > > @@ -89,7 +75,6 @@ static int __hyp_text __guest_run(struct kvm_vcpu *vcpu) > { > struct kvm_cpu_context *host_ctxt; > struct kvm_cpu_context *guest_ctxt; > - bool fp_enabled; > u64 exit_code; > > vcpu = kern_hyp_va(vcpu); > @@ -119,8 +104,6 @@ static int __hyp_text __guest_run(struct kvm_vcpu *vcpu) > exit_code = __guest_enter(vcpu, host_ctxt); > /* And we're baaack! */ > > - fp_enabled = __fpsimd_enabled(); > - > __sysreg_save_state(guest_ctxt); > __sysreg32_save_state(vcpu); > __timer_save_state(vcpu); > @@ -131,11 +114,6 @@ static int __hyp_text __guest_run(struct kvm_vcpu *vcpu) > > __sysreg_restore_state(host_ctxt); > > - if (fp_enabled) { > - __fpsimd_save_state(&guest_ctxt->gp_regs.fp_regs); > - __fpsimd_restore_state(&host_ctxt->gp_regs.fp_regs); > - } > - why do we remove this logic here but preserve something in __sysreg32_save_state() ? > __debug_save_state(vcpu, kern_hyp_va(vcpu->arch.debug_ptr), guest_ctxt); > __debug_cond_restore_host_state(vcpu); > > -- > 1.9.1 > Thanks, -Christoffer From mboxrd@z Thu Jan 1 00:00:00 1970 From: christoffer.dall@linaro.org (Christoffer Dall) Date: Sun, 10 Jan 2016 17:32:23 +0100 Subject: [PATCH v6 6/6] arm/arm64: KVM: Enable armv8 fp/simd enhanced context switch In-Reply-To: <1451167016-3787-1-git-send-email-m.smarduch@samsung.com> References: <1451167016-3787-1-git-send-email-m.smarduch@samsung.com> Message-ID: <20160110163223.GH30867@cbox> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Sat, Dec 26, 2015 at 01:56:56PM -0800, Mario Smarduch wrote: > Enable armv8 enhanced fp/simd context switch. Guest and host registers are only > context switched on first access and vcpu put. > > Signed-off-by: Mario Smarduch > --- > arch/arm/kvm/arm.c | 13 +++++++++++-- > arch/arm64/kernel/asm-offsets.c | 1 + > arch/arm64/kvm/hyp/entry.S | 1 + > arch/arm64/kvm/hyp/switch.c | 26 ++------------------------ > 4 files changed, 15 insertions(+), 26 deletions(-) > > diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c > index b16ed98..633a208 100644 > --- a/arch/arm/kvm/arm.c > +++ b/arch/arm/kvm/arm.c > @@ -316,10 +316,19 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu) > void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu) > { > /* If the fp/simd registers are dirty save guest, restore host. */ > - if (vcpu_vfp_isdirty(vcpu)) > + if (vcpu_vfp_isdirty(vcpu)) { > + > vcpu_restore_host_vfp_state(vcpu); > > - /* Restore host FPEXC trashed in vcpu_load */ > + /* > + * For 32bit guest on arm64 save the guest fpexc register > + * in EL2 mode. > + */ > + if (vcpu_guest_is_32bit(vcpu)) > + vcpu_save_fpexc(vcpu); > + } > + > + /* For arm32 restore host FPEXC trashed in vcpu_load. */ > vcpu_restore_host_fpexc(vcpu); > > /* > diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c > index 94090a6..d69145c 100644 > --- a/arch/arm64/kernel/asm-offsets.c > +++ b/arch/arm64/kernel/asm-offsets.c > @@ -112,6 +112,7 @@ int main(void) > DEFINE(VCPU_ESR_EL2, offsetof(struct kvm_vcpu, arch.fault.esr_el2)); > DEFINE(VCPU_FAR_EL2, offsetof(struct kvm_vcpu, arch.fault.far_el2)); > DEFINE(VCPU_HPFAR_EL2, offsetof(struct kvm_vcpu, arch.fault.hpfar_el2)); > + DEFINE(VCPU_CPTR_EL2, offsetof(struct kvm_vcpu, arch.cptr_el2)); > DEFINE(VCPU_HOST_CONTEXT, offsetof(struct kvm_vcpu, arch.host_cpu_context)); > #endif > #ifdef CONFIG_CPU_PM > diff --git a/arch/arm64/kvm/hyp/entry.S b/arch/arm64/kvm/hyp/entry.S > index fd0fbe9..ce7e903 100644 > --- a/arch/arm64/kvm/hyp/entry.S > +++ b/arch/arm64/kvm/hyp/entry.S > @@ -136,6 +136,7 @@ ENTRY(__fpsimd_guest_restore) > isb > > mrs x3, tpidr_el2 > + str w2, [x3, #VCPU_CPTR_EL2] I'm confused here, why do we need to do this now and not in the previous patch? Maybe it helps if we merge these last two patches into one. > > ldr x0, [x3, #VCPU_HOST_CONTEXT] > kern_hyp_va x0 > diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c > index ca8f5a5..962d179 100644 > --- a/arch/arm64/kvm/hyp/switch.c > +++ b/arch/arm64/kvm/hyp/switch.c > @@ -19,24 +19,10 @@ > > static void __hyp_text __activate_traps(struct kvm_vcpu *vcpu) > { > - u64 val; > - > - /* > - * We are about to set CPTR_EL2.TFP to trap all floating point > - * register accesses to EL2, however, the ARM ARM clearly states that > - * traps are only taken to EL2 if the operation would not otherwise > - * trap to EL1. Therefore, always make sure that for 32-bit guests, > - * we set FPEXC.EN to prevent traps to EL1, when setting the TFP bit. > - */ > - val = vcpu->arch.hcr_el2; > - if (!(val & HCR_RW)) { > - write_sysreg(1 << 30, fpexc32_el2); > - isb(); > - } > - write_sysreg(val, hcr_el2); > + write_sysreg(vcpu->arch.hcr_el2, hcr_el2); > /* Trap on AArch32 cp15 c15 accesses (EL1 or EL0) */ > write_sysreg(1 << 15, hstr_el2); > - write_sysreg(CPTR_EL2_TTA | CPTR_EL2_TFP, cptr_el2); > + write_sysreg(vcpu->arch.cptr_el2, cptr_el2); > write_sysreg(vcpu->arch.mdcr_el2, mdcr_el2); > } > > @@ -89,7 +75,6 @@ static int __hyp_text __guest_run(struct kvm_vcpu *vcpu) > { > struct kvm_cpu_context *host_ctxt; > struct kvm_cpu_context *guest_ctxt; > - bool fp_enabled; > u64 exit_code; > > vcpu = kern_hyp_va(vcpu); > @@ -119,8 +104,6 @@ static int __hyp_text __guest_run(struct kvm_vcpu *vcpu) > exit_code = __guest_enter(vcpu, host_ctxt); > /* And we're baaack! */ > > - fp_enabled = __fpsimd_enabled(); > - > __sysreg_save_state(guest_ctxt); > __sysreg32_save_state(vcpu); > __timer_save_state(vcpu); > @@ -131,11 +114,6 @@ static int __hyp_text __guest_run(struct kvm_vcpu *vcpu) > > __sysreg_restore_state(host_ctxt); > > - if (fp_enabled) { > - __fpsimd_save_state(&guest_ctxt->gp_regs.fp_regs); > - __fpsimd_restore_state(&host_ctxt->gp_regs.fp_regs); > - } > - why do we remove this logic here but preserve something in __sysreg32_save_state() ? > __debug_save_state(vcpu, kern_hyp_va(vcpu->arch.debug_ptr), guest_ctxt); > __debug_cond_restore_host_state(vcpu); > > -- > 1.9.1 > Thanks, -Christoffer