This patch only saves and restores FP/SIMD registers on Guest access. To do this cptr_el2 FP/SIMD trap is set on Guest entry and later checked on exit. lmbench, hackbench show significant improvements, for 30-50% exits FP/SIMD context is not saved/restored Signed-off-by: Mario Smarduch <m.smarduch@xxxxxxxxxxx> --- arch/arm64/include/asm/kvm_arm.h | 5 ++++- arch/arm64/kvm/hyp.S | 46 +++++++++++++++++++++++++++++++++++--- 2 files changed, 47 insertions(+), 4 deletions(-) diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h index ac6fafb..7605e09 100644 --- a/arch/arm64/include/asm/kvm_arm.h +++ b/arch/arm64/include/asm/kvm_arm.h @@ -171,10 +171,13 @@ #define HSTR_EL2_TTEE (1 << 16) #define HSTR_EL2_T(x) (1 << x) +/* Hyp Coproccessor Trap Register Shifts */ +#define CPTR_EL2_TFP_SHIFT 10 + /* Hyp Coprocessor Trap Register */ #define CPTR_EL2_TCPAC (1 << 31) #define CPTR_EL2_TTA (1 << 20) -#define CPTR_EL2_TFP (1 << 10) +#define CPTR_EL2_TFP (1 << CPTR_EL2_TFP_SHIFT) /* Hyp Debug Configuration Register bits */ #define MDCR_EL2_TDRA (1 << 11) diff --git a/arch/arm64/kvm/hyp.S b/arch/arm64/kvm/hyp.S index 5befd01..de0788f 100644 --- a/arch/arm64/kvm/hyp.S +++ b/arch/arm64/kvm/hyp.S @@ -673,6 +673,15 @@ tbz \tmp, #KVM_ARM64_DEBUG_DIRTY_SHIFT, \target .endm +/* + * Check cptr VFP/SIMD accessed bit, if set VFP/SIMD not accessed by guest. + */ +.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. @@ -763,6 +772,7 @@ ldr x2, [x0, #VCPU_HCR_EL2] msr hcr_el2, x2 mov x2, #CPTR_EL2_TTA + orr x2, x2, #CPTR_EL2_TFP msr cptr_el2, x2 mov x2, #(1 << 15) // Trap CP15 Cr=15 @@ -785,7 +795,6 @@ .macro deactivate_traps mov x2, #HCR_RW msr hcr_el2, x2 - msr cptr_el2, xzr msr hstr_el2, xzr mrs x2, mdcr_el2 @@ -912,6 +921,28 @@ __restore_fpsimd: restore_fpsimd ret +switch_to_guest_fpsimd: + push x4, lr + + mrs x2, cptr_el2 + bic x2, x2, #CPTR_EL2_TFP + msr cptr_el2, x2 + + mrs x0, tpidr_el2 + + ldr x2, [x0, #VCPU_HOST_CONTEXT] + kern_hyp_va x2 + bl __save_fpsimd + + add x2, x0, #VCPU_CONTEXT + bl __restore_fpsimd + + pop x4, lr + pop x2, x3 + pop x0, x1 + + eret + /* * u64 __kvm_vcpu_run(struct kvm_vcpu *vcpu); * @@ -932,7 +963,6 @@ ENTRY(__kvm_vcpu_run) kern_hyp_va x2 save_host_regs - bl __save_fpsimd bl __save_sysregs compute_debug_state 1f @@ -948,7 +978,6 @@ ENTRY(__kvm_vcpu_run) add x2, x0, #VCPU_CONTEXT bl __restore_sysregs - bl __restore_fpsimd skip_debug_state x3, 1f bl __restore_debug @@ -967,7 +996,9 @@ __kvm_vcpu_return: add x2, x0, #VCPU_CONTEXT save_guest_regs + skip_fpsimd_state x3, 1f bl __save_fpsimd +1: bl __save_sysregs skip_debug_state x3, 1f @@ -986,7 +1017,11 @@ __kvm_vcpu_return: kern_hyp_va x2 bl __restore_sysregs + skip_fpsimd_state x3, 1f bl __restore_fpsimd +1: + /* Clear FPSIMD and Trace trapping */ + msr cptr_el2, xzr skip_debug_state x3, 1f // Clear the dirty flag for the next run, as all the state has @@ -1201,6 +1236,11 @@ el1_trap: * x1: ESR * x2: ESR_EC */ + + /* Guest accessed VFP/SIMD registers, save host, restore Guest */ + cmp x2, #ESR_ELx_EC_FP_ASIMD + b.eq switch_to_guest_fpsimd + cmp x2, #ESR_ELx_EC_DABT_LOW mov x0, #ESR_ELx_EC_IABT_LOW ccmp x2, x0, #4, ne -- 1.7.9.5 -- 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
