Dave Martin <dave.mar...@arm.com> writes:
> To make the lazy FPSIMD context switch trap code easier to hack on,
> this patch converts it to C.
>
> This is not amazingly efficient, but the trap should typically only
> be taken once per host context switch.
>
> Signed-off-by: Dave Martin <dave.mar...@arm.com>
> Reviewed-by: Marc Zyngier <marc.zyng...@arm.com>
> ---
> arch/arm64/kvm/hyp/entry.S | 57
> +++++++++++++++++----------------------------
> arch/arm64/kvm/hyp/switch.c | 24 +++++++++++++++++++
> 2 files changed, 46 insertions(+), 35 deletions(-)
>
> diff --git a/arch/arm64/kvm/hyp/entry.S b/arch/arm64/kvm/hyp/entry.S
> index e41a161..40f349b 100644
> --- a/arch/arm64/kvm/hyp/entry.S
> +++ b/arch/arm64/kvm/hyp/entry.S
> @@ -172,40 +172,27 @@ ENTRY(__fpsimd_guest_restore)
> // x1: vcpu
> // x2-x29,lr: vcpu regs
> // vcpu x0-x1 on the stack
> - stp x2, x3, [sp, #-16]!
> - stp x4, lr, [sp, #-16]!
> -
> -alternative_if_not ARM64_HAS_VIRT_HOST_EXTN
> - mrs x2, cptr_el2
> - bic x2, x2, #CPTR_EL2_TFP
> - msr cptr_el2, x2
> -alternative_else
> - mrs x2, cpacr_el1
> - orr x2, x2, #CPACR_EL1_FPEN
> - msr cpacr_el1, x2
> -alternative_endif
> - isb
> -
> - mov x3, x1
> -
> - ldr x0, [x3, #VCPU_HOST_CONTEXT]
> - kern_hyp_va x0
> - add x0, x0, #CPU_GP_REG_OFFSET(CPU_FP_REGS)
> - bl __fpsimd_save_state
> -
> - add x2, x3, #VCPU_CONTEXT
> - add x0, x2, #CPU_GP_REG_OFFSET(CPU_FP_REGS)
> - bl __fpsimd_restore_state
> -
> - // Skip restoring fpexc32 for AArch64 guests
> - mrs x1, hcr_el2
> - tbnz x1, #HCR_RW_SHIFT, 1f
> - ldr x4, [x3, #VCPU_FPEXC32_EL2]
> - msr fpexc32_el2, x4
> -1:
> - ldp x4, lr, [sp], #16
> - ldp x2, x3, [sp], #16
> - ldp x0, x1, [sp], #16
> -
> + stp x2, x3, [sp, #-144]!
> + stp x4, x5, [sp, #16]
> + stp x6, x7, [sp, #32]
> + stp x8, x9, [sp, #48]
> + stp x10, x11, [sp, #64]
> + stp x12, x13, [sp, #80]
> + stp x14, x15, [sp, #96]
> + stp x16, x17, [sp, #112]
> + stp x18, lr, [sp, #128]
> +
> + bl __hyp_switch_fpsimd
> +
> + ldp x4, x5, [sp, #16]
> + ldp x6, x7, [sp, #32]
> + ldp x8, x9, [sp, #48]
> + ldp x10, x11, [sp, #64]
> + ldp x12, x13, [sp, #80]
> + ldp x14, x15, [sp, #96]
> + ldp x16, x17, [sp, #112]
> + ldp x18, lr, [sp, #128]
> + ldp x0, x1, [sp, #144]
> + ldp x2, x3, [sp], #160
> eret
> ENDPROC(__fpsimd_guest_restore)
> diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c
> index d964523..c0796c4 100644
> --- a/arch/arm64/kvm/hyp/switch.c
> +++ b/arch/arm64/kvm/hyp/switch.c
> @@ -318,6 +318,30 @@ static bool __hyp_text __skip_instr(struct kvm_vcpu
> *vcpu)
> }
> }
>
> +void __hyp_text __hyp_switch_fpsimd(u64 esr __always_unused,
> + struct kvm_vcpu *vcpu)
> +{
> + kvm_cpu_context_t *host_ctxt;
> +
> + if (has_vhe())
> + write_sysreg(read_sysreg(cpacr_el1) | CPACR_EL1_FPEN,
> + cpacr_el1);
> + else
> + write_sysreg(read_sysreg(cptr_el2) & ~(u64)CPTR_EL2_TFP,
> + cptr_el2);
Is there no way to do alternative() in C or does it always come down to
different inline asms?
Anyway:
Reviewed-by: Alex Bennée <alex.ben...@linaro.org>
> +
> + isb();
> +
> + host_ctxt = kern_hyp_va(vcpu->arch.host_cpu_context);
> + __fpsimd_save_state(&host_ctxt->gp_regs.fp_regs);
> + __fpsimd_restore_state(&vcpu->arch.ctxt.gp_regs.fp_regs);
> +
> + /* Skip restoring fpexc32 for AArch64 guests */
> + if (!(read_sysreg(hcr_el2) & HCR_RW))
> + write_sysreg(vcpu->arch.ctxt.sys_regs[FPEXC32_EL2],
> + fpexc32_el2);
> +}
> +
> /*
> * Return true when we were able to fixup the guest exit and should return to
> * the guest, false when we should restore the host state and return to the
--
Alex Bennée
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