KVM: selftests: Zero out valid_bank_mask for "all" case in Hyper-V IPI test

Zero out the valid_bank_mask when using the fast variant of
HVCALL_SEND_IPI_EX to send IPIs to all vCPUs.  KVM requires the "var_cnt"
and "valid_bank_mask" inputs to be consistent even when targeting all
vCPUs.  See commit bd1ba5732bb9 ("KVM: x86: Get the number of Hyper-V
sparse banks from the VARHEAD field").

Fixes: 998489245d84 ("KVM: selftests: Hyper-V PV IPI selftest")
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20221219220416.395329-1-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/tools/testing/selftests/kvm/x86_64/hyperv_ipi.c b/tools/testing/selftests/kvm/x86_64/hyperv_ipi.c
index 8b791eac7d5a37f90b450249800d0aeecbbc22c2..0cbb0e646ef8d7e7e804b730c773dcfd497a0658 100644 (file)
--- a/tools/testing/selftests/kvm/x86_64/hyperv_ipi.c
+++ b/tools/testing/selftests/kvm/x86_64/hyperv_ipi.c
@@ -193,8 +193,9 @@ static void sender_guest_code(void *hcall_page, vm_vaddr_t pgs_gpa)
        GUEST_SYNC(stage++);
        /*
         * 'XMM Fast' HvCallSendSyntheticClusterIpiEx to HV_GENERIC_SET_ALL.
-        * Nothing to write anything to XMM regs.
         */
+       ipi_ex->vp_set.valid_bank_mask = 0;
+       hyperv_write_xmm_input(&ipi_ex->vp_set.valid_bank_mask, 2);
        hyperv_hypercall(HVCALL_SEND_IPI_EX | HV_HYPERCALL_FAST_BIT,
                         IPI_VECTOR, HV_GENERIC_SET_ALL);
        nop_loop();