tools/testing/selftests/kvm/lib/x86/ucall.c


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// SPDX-License-Identifier: GPL-2.0
/*
 * ucall support. A ucall is a "hypercall to userspace".
 *
 * Copyright (C) 2018, Red Hat, Inc.
 */
#include "kvm_util.h"

#define UCALL_PIO_PORT ((u16)0x1000)

void ucall_arch_do_ucall(gva_t uc)
{
	asm volatile("in %[port], %%al"
		: : [port] "d" (UCALL_PIO_PORT), "D" (uc) : "rax", "memory");
}

void *ucall_arch_get_ucall(struct kvm_vcpu *vcpu)
{
	struct kvm_run *run = vcpu->run;

	if (run->exit_reason == KVM_EXIT_IO && run->io.port == UCALL_PIO_PORT) {
		struct kvm_regs regs;

		vcpu_regs_get(vcpu, &regs);
		return (void *)regs.rdi;
	}
	return NULL;
}