KVM: arm64: Avoid repetitive stack access on host EL1 to EL2 exception (83fa381f) · Commits · 戴 / test

Registers x0/x1 get repeateadly pushed and poped during a host HVC call. Instead, leave the registers on the stack, trading a store instruction on the fast path for an add on the slow path. Reviewed-by:

Alexandru Elisei <alexandru.elisei@arm.com> Signed-off-by:

Marc Zyngier <maz@kernel.org>

arch/arm64/kvm/hyp/nvhe/host.S

+3 −3

Original line number	Diff line number	Diff line
		@@ -13,8 +13,6 @@
		.text

		SYM_FUNC_START(__host_exit)
		stp x0, x1, [sp, #-16]!

		get_host_ctxt x0, x1

		/* Store the host regs x2 and x3 */
		@@ -99,13 +97,15 @@ SYM_FUNC_END(__hyp_do_panic)
		mrs x0, esr_el2
		lsr x0, x0, #ESR_ELx_EC_SHIFT
		cmp x0, #ESR_ELx_EC_HVC64
		ldp x0, x1, [sp], #16
		b.ne __host_exit

		ldp x0, x1, [sp] // Don't fixup the stack yet

		/* Check for a stub HVC call */
		cmp x0, #HVC_STUB_HCALL_NR
		b.hs __host_exit

		add sp, sp, #16
		/*
		* Compute the idmap address of __kvm_handle_stub_hvc and
		* jump there. Since we use kimage_voffset, do not use the

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