1// SPDX-License-Identifier: GPL-2.0
2#include <fcntl.h>
3#include <stdio.h>
4#include <stdlib.h>
5#include <string.h>
6#include <sys/ioctl.h>
7
8#include "test_util.h"
9
10#include "kvm_util.h"
11#include "processor.h"
12
13static void guest_ins_port80(uint8_t *buffer, unsigned int count)
14{
15	unsigned long end;
16
17	if (count == 2)
18		end = (unsigned long)buffer + 1;
19	else
20		end = (unsigned long)buffer + 8192;
21
22	asm volatile("cld; rep; insb" : "+D"(buffer), "+c"(count) : "d"(0x80) : "memory");
23	GUEST_ASSERT_EQ(count, 0);
24	GUEST_ASSERT_EQ((unsigned long)buffer, end);
25}
26
27static void guest_code(void)
28{
29	uint8_t buffer[8192];
30	int i;
31
32	/*
33	 * Special case tests.  main() will adjust RCX 2 => 1 and 3 => 8192 to
34	 * test that KVM doesn't explode when userspace modifies the "count" on
35	 * a userspace I/O exit.  KVM isn't required to play nice with the I/O
36	 * itself as KVM doesn't support manipulating the count, it just needs
37	 * to not explode or overflow a buffer.
38	 */
39	guest_ins_port80(buffer, 2);
40	guest_ins_port80(buffer, 3);
41
42	/* Verify KVM fills the buffer correctly when not stuffing RCX. */
43	memset(buffer, 0, sizeof(buffer));
44	guest_ins_port80(buffer, 8192);
45	for (i = 0; i < 8192; i++)
46		__GUEST_ASSERT(buffer[i] == 0xaa,
47			       "Expected '0xaa', got '0x%x' at buffer[%u]",
48			       buffer[i], i);
49
50	GUEST_DONE();
51}
52
53int main(int argc, char *argv[])
54{
55	struct kvm_vcpu *vcpu;
56	struct kvm_regs regs;
57	struct kvm_run *run;
58	struct kvm_vm *vm;
59	struct ucall uc;
60
61	vm = vm_create_with_one_vcpu(&vcpu, guest_code);
62	run = vcpu->run;
63
64	memset(&regs, 0, sizeof(regs));
65
66	while (1) {
67		vcpu_run(vcpu);
68		TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO);
69
70		if (get_ucall(vcpu, &uc))
71			break;
72
73		TEST_ASSERT(run->io.port == 0x80,
74			    "Expected I/O at port 0x80, got port 0x%x", run->io.port);
75
76		/*
77		 * Modify the rep string count in RCX: 2 => 1 and 3 => 8192.
78		 * Note, this abuses KVM's batching of rep string I/O to avoid
79		 * getting stuck in an infinite loop.  That behavior isn't in
80		 * scope from a testing perspective as it's not ABI in any way,
81		 * i.e. it really is abusing internal KVM knowledge.
82		 */
83		vcpu_regs_get(vcpu, &regs);
84		if (regs.rcx == 2)
85			regs.rcx = 1;
86		if (regs.rcx == 3)
87			regs.rcx = 8192;
88		memset((void *)run + run->io.data_offset, 0xaa, 4096);
89		vcpu_regs_set(vcpu, &regs);
90	}
91
92	switch (uc.cmd) {
93	case UCALL_DONE:
94		break;
95	case UCALL_ABORT:
96		REPORT_GUEST_ASSERT(uc);
97	default:
98		TEST_FAIL("Unknown ucall %lu", uc.cmd);
99	}
100
101	kvm_vm_free(vm);
102	return 0;
103}
104