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KVM: selftests: Explicitly verify KVM doesn't patch hypercall if quirk==off 

Explicitly verify that KVM doesn't patch in the native hypercall if the
FIX_HYPERCALL_INSN quirk is disabled.  The test currently verifies that
a #UD occurred, but doesn't actually verify that no patching occurred.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220928233652.783504-6-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2022-09-28 23:36:50 +00:00 committed by Paolo Bonzini
parent fca6d06cd1
commit b7ab6d7d2c
1 changed files with 18 additions and 8 deletions
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26
tools/testing/selftests/kvm/x86_64/fix_hypercall_test.c
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@ -21,8 +21,8 @@ static bool ud_expected;
static void guest_ud_handler(struct ex_regs *regs)
{
GUEST_ASSERT(ud_expected);
GUEST_DONE();
regs->rax = -EFAULT;
regs->rip += HYPERCALL_INSN_SIZE;
}
static const uint8_t vmx_vmcall[HYPERCALL_INSN_SIZE] = { 0x0f, 0x01, 0xc1 };
@ -46,6 +46,7 @@ static void guest_main(void)
{
const uint8_t *native_hypercall_insn;
const uint8_t *other_hypercall_insn;
uint64_t ret;
if (is_intel_cpu()) {
native_hypercall_insn = vmx_vmcall;
@ -61,15 +62,24 @@ static void guest_main(void)
memcpy(hypercall_insn, other_hypercall_insn, HYPERCALL_INSN_SIZE);
do_sched_yield(GET_APIC_ID_FIELD(xapic_read_reg(APIC_ID)));
ret = do_sched_yield(GET_APIC_ID_FIELD(xapic_read_reg(APIC_ID)));
/*
* The hypercall didn't #UD (guest_ud_handler() signals "done" if a #UD
* occurs). Verify that a #UD is NOT expected and that KVM patched in
* the native hypercall.
* If the quirk is disabled, verify that guest_ud_handler() "returned"
* -EFAULT and that KVM did NOT patch the hypercall. If the quirk is
* enabled, verify that the hypercall succeeded and that KVM patched in
* the "right" hypercall.
*/
GUEST_ASSERT(!ud_expected);
GUEST_ASSERT(!memcmp(native_hypercall_insn, hypercall_insn, HYPERCALL_INSN_SIZE));
if (ud_expected) {
GUEST_ASSERT(ret == (uint64_t)-EFAULT);
GUEST_ASSERT(!memcmp(other_hypercall_insn, hypercall_insn,
HYPERCALL_INSN_SIZE));
} else {
GUEST_ASSERT(!ret);
GUEST_ASSERT(!memcmp(native_hypercall_insn, hypercall_insn,
HYPERCALL_INSN_SIZE));
}
GUEST_DONE();
}