From de81c2f912ef57917bdc6d63b410c534c3e07982 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Wed, 23 Jan 2019 09:22:40 -0800 Subject: [PATCH] KVM: x86: WARN_ONCE if sending a PV IPI returns a fatal error KVM hypercalls return a negative value error code in case of a fatal error, e.g. when the hypercall isn't supported or was made with invalid parameters. WARN_ONCE on fatal errors when sending PV IPIs as any such error all but guarantees an SMP system will hang due to a missing IPI. Fixes: aaffcfd1e82d ("KVM: X86: Implement PV IPIs in linux guest") Cc: stable@vger.kernel.org Cc: Wanpeng Li Signed-off-by: Sean Christopherson Signed-off-by: Paolo Bonzini --- arch/x86/kernel/kvm.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c index ba4bfb7f6a36..5c93a65ee1e5 100644 --- a/arch/x86/kernel/kvm.c +++ b/arch/x86/kernel/kvm.c @@ -457,6 +457,7 @@ static void __send_ipi_mask(const struct cpumask *mask, int vector) #else u64 ipi_bitmap = 0; #endif + long ret; if (cpumask_empty(mask)) return; @@ -482,8 +483,9 @@ static void __send_ipi_mask(const struct cpumask *mask, int vector) } else if (apic_id < min + KVM_IPI_CLUSTER_SIZE) { max = apic_id < max ? max : apic_id; } else { - kvm_hypercall4(KVM_HC_SEND_IPI, (unsigned long)ipi_bitmap, + ret = kvm_hypercall4(KVM_HC_SEND_IPI, (unsigned long)ipi_bitmap, (unsigned long)(ipi_bitmap >> BITS_PER_LONG), min, icr); + WARN_ONCE(ret < 0, "KVM: failed to send PV IPI: %ld", ret); min = max = apic_id; ipi_bitmap = 0; } @@ -491,8 +493,9 @@ static void __send_ipi_mask(const struct cpumask *mask, int vector) } if (ipi_bitmap) { - kvm_hypercall4(KVM_HC_SEND_IPI, (unsigned long)ipi_bitmap, + ret = kvm_hypercall4(KVM_HC_SEND_IPI, (unsigned long)ipi_bitmap, (unsigned long)(ipi_bitmap >> BITS_PER_LONG), min, icr); + WARN_ONCE(ret < 0, "KVM: failed to send PV IPI: %ld", ret); } local_irq_restore(flags); -- 2.39.5