// SPDX-License-Identifier: GPL-2.0-only
/*
* Test for x86 KVM_CAP_SYNC_REGS
*
* Copyright (C) 2018, Google LLC.
*
* Verifies expected behavior of x86 KVM_CAP_SYNC_REGS functionality,
* including requesting an invalid register set, updates to/from values
* in kvm_run.s.regs when kvm_valid_regs and kvm_dirty_regs are toggled.
*/
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <pthread.h>
#include "kvm_test_harness.h"
#include "test_util.h"
#include "kvm_util.h"
#include "processor.h"
#define UCALL_PIO_PORT ((uint16_t)0x1000)
struct ucall uc_none = {
.cmd = UCALL_NONE,
};
/*
* ucall is embedded here to protect against compiler reshuffling registers
* before calling a function. In this test we only need to get KVM_EXIT_IO
* vmexit and preserve RBX, no additional information is needed.
*/
void guest_code(void)
{
asm volatile("1: in %[port], %%al\n"
"add $0x1, %%rbx\n"
"jmp 1b"
: : [port] "d" (UCALL_PIO_PORT), "D" (&uc_none)
: "rax", "rbx");
}
KVM_ONE_VCPU_TEST_SUITE(sync_regs_test);
static void compare_regs(struct kvm_regs *left, struct kvm_regs *right)
{
#define REG_COMPARE(reg) \
TEST_ASSERT(left->reg == right->reg, \
"Register " #reg \
" values did not match: 0x%llx, 0x%llx", \
left->reg, right->reg)
REG_COMPARE(rax);
REG_COMPARE(rbx);
REG_COMPARE(rcx);
REG_COMPARE(rdx);
REG_COMPARE(rsi);
REG_COMPARE(rdi);
REG_COMPARE(rsp);
REG_COMPARE(rbp);
REG_COMPARE(r8);
REG_COMPARE(r9);
REG_COMPARE(r10);
REG_COMPARE(r11);
REG_COMPARE(r12);
REG_COMPARE(r13);
REG_COMPARE(r14);
REG_COMPARE(r15);
REG_COMPARE(rip);
REG_COMPARE(rflags);
#undef REG_COMPARE
}
static void compare_sregs(struct kvm_sregs *left, struct kvm_sregs *right)
{
}
static void compare_vcpu_events(struct kvm_vcpu_events *left,
struct kvm_vcpu_events *right)
{
}
#define TEST_SYNC_FIELDS (KVM_SYNC_X86_REGS|KVM_SYNC_X86_SREGS|KVM_SYNC_X86_EVENTS)
#define INVALID_SYNC_FIELD 0x80000000
/*
* Set an exception as pending *and* injected while KVM is processing events.
* KVM is supposed to ignore/drop pending exceptions if userspace is also
* requesting that an exception be injected.
*/
static void *race_events_inj_pen(void *arg)
{
struct kvm_run *run = (struct kvm_run *)arg;
struct kvm_vcpu_events *events = &run->s.regs.events;
WRITE_ONCE(events->exception.nr, UD_VECTOR);
for (;;) {
WRITE_ONCE(run->kvm_dirty_regs, KVM_SYNC_X86_EVENTS);
WRITE_ONCE(events->flags, 0);
WRITE_ONCE(events->exception.injected, 1);
WRITE_ONCE(events->exception.pending, 1);
pthread_testcancel();
}
return NULL;
}
/*
* Set an invalid exception vector while KVM is processing events. KVM is
* supposed to reject any vector >= 32, as well as NMIs (vector 2).
*/
static void *race_events_exc(void *arg)
{
struct kvm_run *run = (struct kvm_run *)arg;
struct kvm_vcpu_events *events = &run->s.regs.events;
for (;;) {
WRITE_ONCE(run->kvm_dirty_regs, KVM_SYNC_X86_EVENTS);
WRITE_ONCE(events->flags, 0);
WRITE_ONCE(events->exception.nr, UD_VECTOR);
WRITE_ONCE(events->exception.pending, 1);
WRITE_ONCE(events->exception.nr, 255);
pthread_testcancel();
}
return NULL;
}
/*
* Toggle CR4.PAE while KVM is processing SREGS, EFER.LME=1 with CR4.PAE=0 is
* illegal, and KVM's MMU heavily relies on vCPU state being valid.
*/
static noinline void *race_sregs_cr4(void *arg)
{
struct kvm_run *run = (struct kvm_run *)arg;
__u64 *cr4 = &run->s.regs.sregs.cr4;
__u64 pae_enabled = *cr4;
__u64 pae_disabled = *cr4 & ~X86_CR4_PAE;
for (;;) {
WRITE_ONCE(run->kvm_dirty_regs, KVM_SYNC_X86_SREGS);
WRITE_ONCE(*cr4, pae_enabled);
asm volatile(".rept 512\n\t"
"nop\n\t"
".endr");
WRITE_ONCE(*cr4, pae_disabled);
pthread_testcancel();
}
return NULL;
}
static void race_sync_regs(struct kvm_vcpu *vcpu, void *racer)
{
const time_t TIMEOUT = 2; /* seconds, roughly */
struct kvm_x86_state *state;
struct kvm_translation tr;
struct kvm_run *run;
pthread_t thread;
time_t t;
run = vcpu->run;
run->kvm_valid_regs = KVM_SYNC_X86_SREGS;
vcpu_run(vcpu);
run->kvm_valid_regs = 0;
/* Save state *before* spawning the thread that mucks with vCPU state. */
state = vcpu_save_state(vcpu);
/*
* Selftests run 64-bit guests by default, both EFER.LME and CR4.PAE
* should already be set in guest state.
*/
TEST_ASSERT((run->s.regs.sregs.cr4 & X86_CR4_PAE) &&
(run->s.regs.sregs.efer & EFER_LME),
"vCPU should be in long mode, CR4.PAE=%d, EFER.LME=%d",
!!(run->s.regs.sregs.cr4 & X86_CR4_PAE),
!!(run->s.regs.sregs.efer & EFER_LME));
TEST_ASSERT_EQ(pthread_create(&thread, NULL, racer, (void *)run), 0);
for (t = time(NULL) + TIMEOUT; time(NULL) < t;) {
/*
* Reload known good state if the vCPU triple faults, e.g. due
* to the unhandled #GPs being injected. VMX preserves state
* on shutdown, but SVM synthesizes an INIT as the VMCB state
* is architecturally undefined on triple fault.
*/
if (!__vcpu_run(vcpu) && run->exit_reason == KVM_EXIT_SHUTDOWN)
vcpu_load_state(vcpu, state);
if (racer == race_sregs_cr4) {
tr = (struct kvm_translation) { .linear_address = 0 };
__vcpu_ioctl(vcpu, KVM_TRANSLATE, &tr);
}
}
TEST_ASSERT_EQ(pthread_cancel(thread), 0);
TEST_ASSERT_EQ(pthread_join(thread, NULL), 0);
kvm_x86_state_cleanup(state);
}
KVM_ONE_VCPU_TEST(sync_regs_test, read_invalid, guest_code)
{
struct kvm_run *run = vcpu->run;
int rv;
/* Request reading invalid register set from VCPU. */
run->kvm_valid_regs = INVALID_SYNC_FIELD;
rv = _vcpu_run(vcpu);
TEST_ASSERT(rv < 0 && errno == EINVAL,
"Invalid kvm_valid_regs did not cause expected KVM_RUN error: %d",
rv);
run->kvm_valid_regs = 0;
run->kvm_valid_regs = INVALID_SYNC_FIELD | TEST_SYNC_FIELDS;
rv = _vcpu_run(vcpu);
TEST_ASSERT(rv < 0 && errno == EINVAL,
"Invalid kvm_valid_regs did not cause expected KVM_RUN error: %d",
rv);
run->kvm_valid_regs = 0;
}
KVM_ONE_VCPU_TEST(sync_regs_test, set_invalid, guest_code)
{
struct kvm_run *run = vcpu->run;
int rv;
/* Request setting invalid register set into VCPU. */
run->kvm_dirty_regs = INVALID_SYNC_FIELD;
rv = _vcpu_run(vcpu);
TEST_ASSERT(rv < 0 && errno == EINVAL,
"Invalid kvm_dirty_regs did not cause expected KVM_RUN error: %d",
rv);
run->kvm_dirty_regs = 0;
run->kvm_dirty_regs = INVALID_SYNC_FIELD | TEST_SYNC_FIELDS;
rv = _vcpu_run(vcpu);
TEST_ASSERT(rv < 0 && errno == EINVAL,
"Invalid kvm_dirty_regs did not cause expected KVM_RUN error: %d",
rv);
run->kvm_dirty_regs = 0;
}
KVM_ONE_VCPU_TEST(sync_regs_test, req_and_verify_all_valid, guest_code)
{
struct kvm_run *run = vcpu->run;
struct kvm_vcpu_events events;
struct kvm_sregs sregs;
struct kvm_regs regs;
/* Request and verify all valid register sets. */
/* TODO: BUILD TIME CHECK: TEST_ASSERT(KVM_SYNC_X86_NUM_FIELDS != 3); */
run->kvm_valid_regs = TEST_SYNC_FIELDS;
vcpu_run(vcpu);
TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO);
vcpu_regs_get(vcpu, ®s);
compare_regs(®s, &run->s.regs.regs);
vcpu_sregs_get(vcpu, &sregs);
compare_sregs(&sregs, &run->s.regs.sregs);
vcpu_events_get(vcpu, &events);
compare_vcpu_events(&events, &run->s.regs.events);
}
KVM_ONE_VCPU_TEST(sync_regs_test, set_and_verify_various, guest_code)
{
struct kvm_run *run = vcpu->run;
struct kvm_vcpu_events events;
struct kvm_sregs sregs;
struct kvm_regs regs;
/* Run once to get register set */
run->kvm_valid_regs = TEST_SYNC_FIELDS;
vcpu_run(vcpu);
TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO);
/* Set and verify various register values. */
run->s.regs.regs.rbx = 0xBAD1DEA;
run->s.regs.sregs.apic_base = 1 << 11;
/* TODO run->s.regs.events.XYZ = ABC; */
run->kvm_valid_regs = TEST_SYNC_FIELDS;
run->kvm_dirty_regs = KVM_SYNC_X86_REGS | KVM_SYNC_X86_SREGS;
vcpu_run(vcpu);
TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO);
TEST_ASSERT(run->s.regs.regs.rbx == 0xBAD1DEA + 1,
"rbx sync regs value incorrect 0x%llx.",
run->s.regs.regs.rbx);
TEST_ASSERT(run->s.regs.sregs.apic_base == 1 << 11,
"apic_base sync regs value incorrect 0x%llx.",
run->s.regs.sregs.apic_base);
vcpu_regs_get(vcpu, ®s);
compare_regs(®s, &run->s.regs.regs);
vcpu_sregs_get(vcpu, &sregs);
compare_sregs(&sregs, &run->s.regs.sregs);
vcpu_events_get(vcpu, &events);
compare_vcpu_events(&events, &run->s.regs.events);
}
KVM_ONE_VCPU_TEST(sync_regs_test, clear_kvm_dirty_regs_bits, guest_code)
{
struct kvm_run *run = vcpu->run;
/* Clear kvm_dirty_regs bits, verify new s.regs values are
* overwritten with existing guest values.
*/
run->kvm_valid_regs = TEST_SYNC_FIELDS;
run->kvm_dirty_regs = 0;
run->s.regs.regs.rbx = 0xDEADBEEF;
vcpu_run(vcpu);
TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO);
TEST_ASSERT(run->s.regs.regs.rbx != 0xDEADBEEF,
"rbx sync regs value incorrect 0x%llx.",
run->s.regs.regs.rbx);
}
KVM_ONE_VCPU_TEST(sync_regs_test, clear_kvm_valid_and_dirty_regs, guest_code)
{
struct kvm_run *run = vcpu->run;
struct kvm_regs regs;
/* Run once to get register set */
run->kvm_valid_regs = TEST_SYNC_FIELDS;
vcpu_run(vcpu);
TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO);
/* Clear kvm_valid_regs bits and kvm_dirty_bits.
* Verify s.regs values are not overwritten with existing guest values
* and that guest values are not overwritten with kvm_sync_regs values.
*/
run->kvm_valid_regs = 0;
run->kvm_dirty_regs = 0;
run->s.regs.regs.rbx = 0xAAAA;
vcpu_regs_get(vcpu, ®s);
regs.rbx = 0xBAC0;
vcpu_regs_set(vcpu, ®s);
vcpu_run(vcpu);
TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO);
TEST_ASSERT(run->s.regs.regs.rbx == 0xAAAA,
"rbx sync regs value incorrect 0x%llx.",
run->s.regs.regs.rbx);
vcpu_regs_get(vcpu, ®s);
TEST_ASSERT(regs.rbx == 0xBAC0 + 1,
"rbx guest value incorrect 0x%llx.",
regs.rbx);
}
KVM_ONE_VCPU_TEST(sync_regs_test, clear_kvm_valid_regs_bits, guest_code)
{
struct kvm_run *run = vcpu->run;
struct kvm_regs regs;
/* Run once to get register set */
run->kvm_valid_regs = TEST_SYNC_FIELDS;
vcpu_run(vcpu);
TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO);
/* Clear kvm_valid_regs bits. Verify s.regs values are not overwritten
* with existing guest values but that guest values are overwritten
* with kvm_sync_regs values.
*/
run->kvm_valid_regs = 0;
run->kvm_dirty_regs = TEST_SYNC_FIELDS;
run->s.regs.regs.rbx = 0xBBBB;
vcpu_run(vcpu);
TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO);
TEST_ASSERT(run->s.regs.regs.rbx == 0xBBBB,
"rbx sync regs value incorrect 0x%llx.",
run->s.regs.regs.rbx);
vcpu_regs_get(vcpu, ®s);
TEST_ASSERT(regs.rbx == 0xBBBB + 1,
"rbx guest value incorrect 0x%llx.",
regs.rbx);
}
KVM_ONE_VCPU_TEST(sync_regs_test, race_cr4, guest_code)
{
race_sync_regs(vcpu, race_sregs_cr4);
}
KVM_ONE_VCPU_TEST(sync_regs_test, race_exc, guest_code)
{
race_sync_regs(vcpu, race_events_exc);
}
KVM_ONE_VCPU_TEST(sync_regs_test, race_inj_pen, guest_code)
{
race_sync_regs(vcpu, race_events_inj_pen);
}
int main(int argc, char *argv[])
{
int cap;
cap = kvm_check_cap(KVM_CAP_SYNC_REGS);
TEST_REQUIRE((cap & TEST_SYNC_FIELDS) == TEST_SYNC_FIELDS);
TEST_REQUIRE(!(cap & INVALID_SYNC_FIELD));
return test_harness_run(argc, argv);
}
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