[PATCH 2/2] KVM: Check if __pv_cpu_mask was allocated instead of assigning ops too late

[lihaiwei . kernel]

From: Haiwei Li <lihai...@tencent.com>

Without this patch, kvm_flush_tlb_others is not called. We can always check
if __pv_cpu_mask was allocated and revert back to the architectural path if
not.

Suggested-by: Vitaly Kuznetsov <vkuzn...@redhat.com>
Signed-off-by: Haiwei Li <lihai...@tencent.com>
---
 arch/x86/kernel/kvm.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index 7e8be0421720..3c6c516d9828 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -553,7 +553,6 @@ static void kvm_send_ipi_mask_allbutself(const struct 
cpumask *mask, int vector)
 static void kvm_setup_pv_ipi(void)
 {
        apic->send_IPI_mask = kvm_send_ipi_mask;
-       apic->send_IPI_mask_allbutself = kvm_send_ipi_mask_allbutself;
        pr_info("setup PV IPIs\n");
 }
 
@@ -619,6 +618,11 @@ static void kvm_flush_tlb_others(const struct cpumask 
*cpumask,
        struct kvm_steal_time *src;
        struct cpumask *flushmask = this_cpu_cpumask_var_ptr(__pv_cpu_mask);
 
+       if (unlikely(!flushmask)) {
+               native_flush_tlb_others(cpumask, info);
+               return;
+       }
+
        cpumask_copy(flushmask, cpumask);
        /*
         * We have to call flush only on online vCPUs. And
@@ -652,6 +656,7 @@ static void __init kvm_guest_init(void)
        }
 
        if (pv_tlb_flush_supported()) {
+               pv_ops.mmu.flush_tlb_others = kvm_flush_tlb_others;
                pv_ops.mmu.tlb_remove_table = tlb_remove_table;
                pr_info("KVM setup pv remote TLB flush\n");
        }
@@ -800,7 +805,6 @@ static __init int kvm_alloc_cpumask(void)
 #if defined(CONFIG_SMP)
        apic->send_IPI_mask_allbutself = kvm_send_ipi_mask_allbutself;
 #endif
-       pv_ops.mmu.flush_tlb_others = kvm_flush_tlb_others;
        return 0;
 
 zalloc_cpumask_fail:
-- 
2.18.4