Commit ceda9fff authored by Dave Martin's avatar Dave Martin Committed by Marc Zyngier
Browse files

KVM: arm64: Convert lazy FPSIMD context switch trap to C 



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: default avatarDave Martin <Dave.Martin@arm.com>
Reviewed-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
Reviewed-by: default avatarAlex Bennée <alex.bennee@linaro.org>
Signed-off-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
parent bd2a6394

arch/arm64/kvm/hyp/entry.S

+22 −35
Original line number Diff line number Diff line
@@ -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)

arch/arm64/kvm/hyp/switch.c

+24 −0
Original line number Diff line number Diff line
@@ -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);



	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

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