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

[Sean Christopherson]

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@xxxxxxxxxx>
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
 tools/testing/selftests/kvm/x86_64/hyperv_ipi.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/kvm/x86_64/hyperv_ipi.c b/tools/testing/selftests/kvm/x86_64/hyperv_ipi.c
index 8b791eac7d5a..0cbb0e646ef8 100644
--- 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();

base-commit: 9d75a3251adfbcf444681474511b58042a364863
-- 
2.39.0.314.g84b9a713c41-goog