On Mon, Oct 05, 2015 at 07:33:14PM -0700, Mario Smarduch wrote: > This patch enables arm64 lazy fp/simd switch. Removes the ARM constraint, > and follows the same approach as armv7 version - found here. > > https://lists.cs.columbia.edu/pipermail/kvmarm/2015-September/016567.html > > To summarize - provided the guest accesses fp/simd unit we limit number > of fp/simd context switches to two per vCPU execution schedule. > > Signed-off-by: Mario Smarduch <m.smarduch@xxxxxxxxxxx> > --- > arch/arm/kvm/arm.c | 2 -- > arch/arm64/include/asm/kvm_asm.h | 1 + > arch/arm64/kvm/hyp.S | 59 +++++++++++++++++++++++++++------------- > 3 files changed, 41 insertions(+), 21 deletions(-) > > diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c > index 1b1f9e9..fe609f1 100644 > --- a/arch/arm/kvm/arm.c > +++ b/arch/arm/kvm/arm.c > @@ -112,12 +112,10 @@ void kvm_arch_check_processor_compat(void *rtn) > */ > static void kvm_switch_fp_regs(struct kvm_vcpu *vcpu) > { > -#ifdef CONFIG_ARM > if (vcpu->arch.vfp_lazy == 1) { > kvm_call_hyp(__kvm_restore_host_vfp_state, vcpu); > vcpu->arch.vfp_lazy = 0; > } > -#endif I'm assuming you'll rework this like for the 32-bit series to just do this in EL1, yes? > } > > /** > diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h > index 5e37710..83dcac5 100644 > --- a/arch/arm64/include/asm/kvm_asm.h > +++ b/arch/arm64/include/asm/kvm_asm.h > @@ -117,6 +117,7 @@ extern char __kvm_hyp_vector[]; > extern void __kvm_flush_vm_context(void); > extern void __kvm_tlb_flush_vmid_ipa(struct kvm *kvm, phys_addr_t ipa); > extern void __kvm_tlb_flush_vmid(struct kvm *kvm); > +extern void __kvm_restore_host_vfp_state(struct kvm_vcpu *vcpu); > > extern int __kvm_vcpu_run(struct kvm_vcpu *vcpu); > > diff --git a/arch/arm64/kvm/hyp.S b/arch/arm64/kvm/hyp.S > index e583613..ea99f66 100644 > --- a/arch/arm64/kvm/hyp.S > +++ b/arch/arm64/kvm/hyp.S > @@ -385,14 +385,6 @@ > tbz \tmp, #KVM_ARM64_DEBUG_DIRTY_SHIFT, \target > .endm > > -/* > - * Branch to target if CPTR_EL2.TFP bit is set (VFP/SIMD trapping enabled) > - */ > -.macro skip_fpsimd_state tmp, target > - mrs \tmp, cptr_el2 > - tbnz \tmp, #CPTR_EL2_TFP_SHIFT, \target > -.endm > - > .macro compute_debug_state target > // Compute debug state: If any of KDE, MDE or KVM_ARM64_DEBUG_DIRTY > // is set, we do a full save/restore cycle and disable trapping. > @@ -433,10 +425,6 @@ > mrs x5, ifsr32_el2 > stp x4, x5, [x3] > > - skip_fpsimd_state x8, 2f > - mrs x6, fpexc32_el2 > - str x6, [x3, #16] > -2: > skip_debug_state x8, 1f > mrs x7, dbgvcr32_el2 > str x7, [x3, #24] > @@ -481,8 +469,15 @@ > isb > 99: > msr hcr_el2, x2 > - mov x2, #CPTR_EL2_TTA > + > + mov x2, #0 > + ldr w3, [x0, #VCPU_VFP_LAZY] > + tbnz w3, #0, 98f > + > orr x2, x2, #CPTR_EL2_TFP > +98: > + orr x2, x2, #CPTR_EL2_TTA > + this can be reworked more simply by using an extra register and leaving the initial mov x2, #CPTR_EL2_TTA alone and just skip setting the TFP bit if we've already switched the state. > msr cptr_el2, x2 > > mov x2, #(1 << 15) // Trap CP15 Cr=15 > @@ -669,14 +664,12 @@ __restore_debug: > ret > > __save_fpsimd: > - skip_fpsimd_state x3, 1f > save_fpsimd > -1: ret > + ret > > __restore_fpsimd: > - skip_fpsimd_state x3, 1f > restore_fpsimd > -1: ret > + ret > > switch_to_guest_fpsimd: > push x4, lr > @@ -688,6 +681,9 @@ switch_to_guest_fpsimd: > > mrs x0, tpidr_el2 > > + mov w2, #1 > + str w2, [x0, #VCPU_VFP_LAZY] > + > ldr x2, [x0, #VCPU_HOST_CONTEXT] > kern_hyp_va x2 > bl __save_fpsimd > @@ -763,7 +759,6 @@ __kvm_vcpu_return: > add x2, x0, #VCPU_CONTEXT > > save_guest_regs > - bl __save_fpsimd > bl __save_sysregs > > skip_debug_state x3, 1f > @@ -784,7 +779,6 @@ __kvm_vcpu_return: > kern_hyp_va x2 > > bl __restore_sysregs > - bl __restore_fpsimd > /* Clear FPSIMD and Trace trapping */ > msr cptr_el2, xzr > > @@ -863,6 +857,33 @@ ENTRY(__kvm_flush_vm_context) > ret > ENDPROC(__kvm_flush_vm_context) > > +/** > + * kvm_switch_fp_regs() - switch guest/host VFP/SIMD registers > + * @vcpu: pointer to vcpu structure. > + * > + */ > +ENTRY(__kvm_restore_host_vfp_state) > + push x4, lr even when you move this to el1, I don't think you need to do the additional store of the registers as this is going to be called from C-code and you should have plenty of caller-save registers, if I read the aarch64 PCS correctly. > + > + kern_hyp_va x0 > + add x2, x0, #VCPU_CONTEXT > + > + // Load Guest HCR, determine if guest is 32 or 64 bit > + ldr x3, [x0, #VCPU_HCR_EL2] > + tbnz x3, #HCR_RW_SHIFT, 1f > + mrs x4, fpexc32_el2 > + str x4, [x2, #CPU_SYSREG_OFFSET(FPEXC32_EL2)] > +1: > + bl __save_fpsimd > + > + ldr x2, [x0, #VCPU_HOST_CONTEXT] > + kern_hyp_va x2 > + bl __restore_fpsimd > + > + pop x4, lr > + ret > +ENDPROC(__kvm_restore_host_vfp_state) > + > __kvm_hyp_panic: > // Guess the context by looking at VTTBR: > // If zero, then we're already a host. > -- > 1.9.1 > Otherwise this looks reasonably good. Thanks, -Christoffer -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
