Commit 2f5213b8 authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

KVM: selftests: Use magic value to signal ucall_alloc() failure 



Use a magic value to signal a ucall_alloc() failure instead of simply
doing GUEST_ASSERT().  GUEST_ASSERT() relies on ucall_alloc() and so a
failure puts the guest into an infinite loop.

Use -1 as the magic value, as a real ucall struct should never wrap.

Reported-by: default avatarOliver Upton <oliver.upton@linux.dev>
Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent db7b780d

tools/testing/selftests/kvm/lib/ucall_common.c

+14 −2
Original line number Diff line number Diff line
@@ -4,6 +4,8 @@ 
#include "linux/bitmap.h"

#include "linux/atomic.h"



#define GUEST_UCALL_FAILED -1



struct ucall_header {

	DECLARE_BITMAP(in_use, KVM_MAX_VCPUS);

	struct ucall ucalls[KVM_MAX_VCPUS];
@@ -41,7 +43,8 @@ static struct ucall *ucall_alloc(void) 
	struct ucall *uc;

	int i;



	GUEST_ASSERT(ucall_pool);

	if (!ucall_pool)

		goto ucall_failed;



	for (i = 0; i < KVM_MAX_VCPUS; ++i) {

		if (!test_and_set_bit(i, ucall_pool->in_use)) {
@@ -51,7 +54,13 @@ static struct ucall *ucall_alloc(void) 
		}

	}



	GUEST_ASSERT(0);

ucall_failed:

	/*

	 * If the vCPU cannot grab a ucall structure, make a bare ucall with a

	 * magic value to signal to get_ucall() that things went sideways.

	 * GUEST_ASSERT() depends on ucall_alloc() and so cannot be used here.

	 */

	ucall_arch_do_ucall(GUEST_UCALL_FAILED);

	return NULL;

}
@@ -93,6 +102,9 @@ uint64_t get_ucall(struct kvm_vcpu *vcpu, struct ucall *uc) 


	addr = ucall_arch_get_ucall(vcpu);

	if (addr) {

		TEST_ASSERT(addr != (void *)GUEST_UCALL_FAILED,

			    "Guest failed to allocate ucall struct");



		memcpy(uc, addr, sizeof(*uc));

		vcpu_run_complete_io(vcpu);

	} else {