Currently 'apic_arb_prio' is int32_t, it's too short for long
time running. In our environment, it overflowed and then the
UBSAN was angry:
signed integer overflow:
2147483647 + 1 cannot be represented in type 'int'
CPU: 22 PID: 31237 Comm: qemu-kvm Tainted: ...
...
Call Trace:
[<ffffffff81f030b6>] dump_stack+0x1e/0x20
[<ffffffff81f03173>] ubsan_epilogue+0x12/0x55
[<ffffffff81f04658>] handle_overflow+0x1ba/0x215
[<ffffffff81f046dd>] __ubsan_handle_add_overflow+0x2a/0x31
[<ffffffffa126cb1a>] __apic_accept_irq+0x57a/0x5d0 [kvm]
[<ffffffffa126d14f>] kvm_apic_set_irq+0x9f/0xf0 [kvm]
[<ffffffffa126db20>] kvm_irq_delivery_to_apic_fast+0x450/0x910 [kvm]
[<ffffffffa127d8ea>] kvm_irq_delivery_to_apic+0xfa/0x7a0 [kvm]
[<ffffffffa127e039>] kvm_set_msi+0xa9/0x100 [kvm]
[<ffffffffa12871ed>] kvm_send_userspace_msi+0x14d/0x1f0 [kvm]
[<ffffffffa11ed56e>] kvm_vm_ioctl+0x4ee/0xdd0 [kvm]
...
We expand it to u64, this is large enough. Suppose the vcpu receives
1000 irqs per second, then it won't overflow in 584942417 years.
( 18446744073709551615/1000/3600/24/365 = 584942417 )
Signed-off-by: Longpeng(Mike) <longpe...@huawei.com>
---
arch/x86/include/asm/kvm_host.h | 2 +-
arch/x86/kvm/ioapic.h | 3 ++-
arch/x86/kvm/irq_comm.c | 2 +-
arch/x86/kvm/lapic.c | 6 +++---
4 files changed, 7 insertions(+), 6 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 87ac4fb..ce9a5f5 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -499,7 +499,7 @@ struct kvm_vcpu_arch {
bool apicv_active;
DECLARE_BITMAP(ioapic_handled_vectors, 256);
unsigned long apic_attention;
- int32_t apic_arb_prio;
+ u64 apic_arb_prio;
int mp_state;
u64 ia32_misc_enable_msr;
u64 smbase;
diff --git a/arch/x86/kvm/ioapic.h b/arch/x86/kvm/ioapic.h
index 29ce197..a26deed 100644
--- a/arch/x86/kvm/ioapic.h
+++ b/arch/x86/kvm/ioapic.h
@@ -117,7 +117,8 @@ static inline int ioapic_in_kernel(struct kvm *kvm)
void kvm_rtc_eoi_tracking_restore_one(struct kvm_vcpu *vcpu);
bool kvm_apic_match_dest(struct kvm_vcpu *vcpu, struct kvm_lapic *source,
int short_hand, unsigned int dest, int dest_mode);
-int kvm_apic_compare_prio(struct kvm_vcpu *vcpu1, struct kvm_vcpu *vcpu2);
+/* Return true if vcpu1's priority is lower */
+bool kvm_apic_compare_prio(struct kvm_vcpu *vcpu1, struct kvm_vcpu *vcpu2);
void kvm_ioapic_update_eoi(struct kvm_vcpu *vcpu, int vector,
int trigger_mode);
int kvm_ioapic_init(struct kvm *kvm);
diff --git a/arch/x86/kvm/irq_comm.c b/arch/x86/kvm/irq_comm.c
index 3cc3b2d..03b1487 100644
--- a/arch/x86/kvm/irq_comm.c
+++ b/arch/x86/kvm/irq_comm.c
@@ -90,7 +90,7 @@ int kvm_irq_delivery_to_apic(struct kvm *kvm, struct
kvm_lapic *src,
if (!kvm_vector_hashing_enabled()) {
if (!lowest)
lowest = vcpu;
- else if (kvm_apic_compare_prio(vcpu, lowest) <
0)
+ else if (kvm_apic_compare_prio(vcpu, lowest))
lowest = vcpu;
} else {
__set_bit(i, dest_vcpu_bitmap);
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 589dcc1..1e2b1f2 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -840,7 +840,7 @@ static inline bool kvm_apic_map_get_dest_lapic(struct kvm
*kvm,
if (lowest < 0)
lowest = i;
else if (kvm_apic_compare_prio((*dst)[i]->vcpu,
- (*dst)[lowest]->vcpu) < 0)
+ (*dst)[lowest]->vcpu))
lowest = i;
}
} else {
@@ -1048,9 +1048,9 @@ static int __apic_accept_irq(struct kvm_lapic *apic, int
delivery_mode,
return result;
}
-int kvm_apic_compare_prio(struct kvm_vcpu *vcpu1, struct kvm_vcpu *vcpu2)
+bool kvm_apic_compare_prio(struct kvm_vcpu *vcpu1, struct kvm_vcpu *vcpu2)
{
- return vcpu1->arch.apic_arb_prio - vcpu2->arch.apic_arb_prio;
+ return vcpu1->arch.apic_arb_prio < vcpu2->arch.apic_arb_prio;
}
static bool kvm_ioapic_handles_vector(struct kvm_lapic *apic, int vector)
--
1.8.3.1
