4.20-stable review patch. If anyone has any objections, please let me know.
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From: Sean Christopherson sean.j.christopherson@intel.com
commit de81c2f912ef57917bdc6d63b410c534c3e07982 upstream.
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 wanpengli@tencent.com Signed-off-by: Sean Christopherson sean.j.christopherson@intel.com Signed-off-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/x86/kernel/kvm.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)
--- a/arch/x86/kernel/kvm.c +++ b/arch/x86/kernel/kvm.c @@ -457,6 +457,7 @@ static void __send_ipi_mask(const struct #else u64 ipi_bitmap = 0; #endif + long ret;
if (cpumask_empty(mask)) return; @@ -482,8 +483,9 @@ static void __send_ipi_mask(const struct } 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 }
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);