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 } /** 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 + 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 + + 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 -- 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
