linux-kernel - [PATCH v2 4/4] KVM: selftests: Add EVTCHNOP_send slow path test to xen_shinfo

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20230204024151.1373296-5-seanjc@google.com>
Date:   Sat,  4 Feb 2023 02:41:51 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Sean Christopherson <seanjc@...gle.com>,
        David Woodhouse <dwmw@...zon.co.uk>
Subject: [PATCH v2 4/4] KVM: selftests: Add EVTCHNOP_send slow path test to xen_shinfo_test

From: David Woodhouse <dwmw@...zon.co.uk>

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: David Woodhouse <dwmw@...zon.co.uk>
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 .../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