| From | Greg Kroah-Hartman <> | Subject | [PATCH 5.10 535/599] KVM: x86: fix sending PV IPI | Date | Tue, 5 Apr 2022 09:33:49 +0200 |
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From: Li RongQing <lirongqing@baidu.com>
commit c15e0ae42c8e5a61e9aca8aac920517cf7b3e94e upstream.
If apic_id is less than min, and (max - apic_id) is greater than KVM_IPI_CLUSTER_SIZE, then the third check condition is satisfied but the new apic_id does not fit the bitmask. In this case __send_ipi_mask should send the IPI.
This is mostly theoretical, but it can happen if the apic_ids on three iterations of the loop are for example 1, KVM_IPI_CLUSTER_SIZE, 0.
Fixes: aaffcfd1e82 ("KVM: X86: Implement PV IPIs in linux guest") Signed-off-by: Li RongQing <lirongqing@baidu.com> Message-Id: <1646814944-51801-1-git-send-email-lirongqing@baidu.com> Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- arch/x86/kernel/kvm.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/x86/kernel/kvm.c +++ b/arch/x86/kernel/kvm.c @@ -532,7 +532,7 @@ static void __send_ipi_mask(const struct } else if (apic_id < min && max - apic_id < KVM_IPI_CLUSTER_SIZE) { ipi_bitmap <<= min - apic_id; min = apic_id; - } else if (apic_id < min + KVM_IPI_CLUSTER_SIZE) { + } else if (apic_id > min && apic_id < min + KVM_IPI_CLUSTER_SIZE) { max = apic_id < max ? max : apic_id; } else { ret = kvm_hypercall4(KVM_HC_SEND_IPI, (unsigned long)ipi_bitmap,
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