[tip:x86/hyperv] x86/hyper-v: Check cpumask_to_vpset() return value in hyperv_flush_tlb_others_ex()

[tip-bot for Vitaly Kuznetsov <tipbot@zytor.com>]

Commit-ID:  0f0caa52cd4a48a44f6cdc77bf83272bbb450727
Gitweb:     https://git.kernel.org/tip/0f0caa52cd4a48a44f6cdc77bf83272bbb450727
Author:     Vitaly Kuznetsov <vkuznets@redhat.com>
AuthorDate: Mon, 9 Jul 2018 19:40:11 +0200
Committer:  Thomas Gleixner <tglx@linutronix.de>
CommitDate: Mon, 16 Jul 2018 11:19:48 +0200

x86/hyper-v: Check cpumask_to_vpset() return value in hyperv_flush_tlb_others_ex()

Commit 1268ed0c474a ("x86/hyper-v: Fix the circular dependency in IPI
enlightenment") made cpumask_to_vpset() return '-1' when there is a CPU
with unknown VP index in the supplied set. This needs to be checked before
we pass 'nr_bank' to hypercall.

Fixes: 1268ed0c474a ("x86/hyper-v: Fix the circular dependency in IPI enlightenment")
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: "Michael Kelley (EOSG)" <Michael.H.Kelley@microsoft.com>
Cc: devel@linuxdriverproject.org
Cc: "H. Peter Anvin" <hpa@zytor.com>
Link: https://lkml.kernel.org/r/20180709174012.17429-2-vkuznets@redhat.com

---
 arch/x86/hyperv/mmu.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/hyperv/mmu.c b/arch/x86/hyperv/mmu.c
index 0d90e515ec98..453d2355cd61 100644
--- a/arch/x86/hyperv/mmu.c
+++ b/arch/x86/hyperv/mmu.c
@@ -186,6 +186,8 @@ static u64 hyperv_flush_tlb_others_ex(const struct cpumask *cpus,
 
 	flush->hv_vp_set.format = HV_GENERIC_SET_SPARSE_4K;
 	nr_bank = cpumask_to_vpset(&(flush->hv_vp_set), cpus);
+	if (nr_bank < 0)
+		return U64_MAX;
 
 	/*
 	 * We can flush not more than max_gvas with one hypercall. Flush the