Commit e6239a4e authored by David Woodhouse's avatar David Woodhouse Committed by Paolo Bonzini
Browse files

KVM: selftests: Add EVTCHNOP_send slow path test to xen_shinfo_test 

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@infradead.org


Signed-off-by: default avatarDavid Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Message-Id: <20230204024151.1373296-5-seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent e7062a98

tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c

+27 −0
Original line number Diff line number Diff line
@@ -26,6 +26,9 @@ 
#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)
@@ -54,6 +57,7 @@ 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,
@@ -260,6 +264,16 @@ 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
@@ -753,6 +767,19 @@ 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");