From: David Woodhouse <dwmw@xxxxxxxxxxxx> When kvm_xen_evtchn_send() takes the slow path because the shinfo GPC needs to be revalidated, it used to violate the SRCU vs. kvm->lock locking rules and potentially cause a deadlock. Now that lockdep is learning to catch such things, make sure that code path is exercised by the selftest. Link: https://lore.kernel.org/all/20230113124606.10221-2-dwmw2@xxxxxxxxxxxxx Signed-off-by: David Woodhouse <dwmw@xxxxxxxxxxxx> Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx> --- .../selftests/kvm/x86_64/xen_shinfo_test.c | 27 +++++++++++++++++++ 1 file changed, 27 insertions(+) diff --git a/tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c b/tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c index 0459126365c9..f8baef107a1b 100644 --- a/tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c +++ b/tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c @@ -29,6 +29,9 @@ #define DUMMY_REGION_GPA (SHINFO_REGION_GPA + (3 * PAGE_SIZE)) #define DUMMY_REGION_SLOT 11 +#define DUMMY_REGION_GPA_2 (SHINFO_REGION_GPA + (4 * PAGE_SIZE)) +#define DUMMY_REGION_SLOT_2 12 + #define SHINFO_ADDR (SHINFO_REGION_GPA) #define VCPU_INFO_ADDR (SHINFO_REGION_GPA + 0x40) #define PVTIME_ADDR (SHINFO_REGION_GPA + PAGE_SIZE) @@ -57,6 +60,7 @@ enum { TEST_EVTCHN_SLOWPATH, TEST_EVTCHN_SEND_IOCTL, TEST_EVTCHN_HCALL, + TEST_EVTCHN_HCALL_SLOWPATH, TEST_EVTCHN_HCALL_EVENTFD, TEST_TIMER_SETUP, TEST_TIMER_WAIT, @@ -263,6 +267,16 @@ static void guest_code(void) guest_wait_for_irq(); + GUEST_SYNC(TEST_EVTCHN_HCALL_SLOWPATH); + + /* + * Same again, but this time the host has messed with memslots so it + * should take the slow path in kvm_xen_set_evtchn(). + */ + xen_hypercall(__HYPERVISOR_event_channel_op, EVTCHNOP_send, &s); + + guest_wait_for_irq(); + GUEST_SYNC(TEST_EVTCHN_HCALL_EVENTFD); /* Deliver "outbound" event channel to an eventfd which @@ -755,6 +769,19 @@ int main(int argc, char *argv[]) alarm(1); break; + case TEST_EVTCHN_HCALL_SLOWPATH: + TEST_ASSERT(!evtchn_irq_expected, + "Expected event channel IRQ but it didn't happen"); + shinfo->evtchn_pending[0] = 0; + + if (verbose) + printf("Testing guest EVTCHNOP_send direct to evtchn after memslot change\n"); + vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS, + DUMMY_REGION_GPA_2, DUMMY_REGION_SLOT_2, 1, 0); + evtchn_irq_expected = true; + alarm(1); + break; + case TEST_EVTCHN_HCALL_EVENTFD: TEST_ASSERT(!evtchn_irq_expected, "Expected event channel IRQ but it didn't happen"); -- 2.39.1.519.gcb327c4b5f-goog
