* [PATCH] KVM: x86/xen: Use a safer data type for delta to avoid shift-count-overflow
@ 2022-03-09 6:43 Like Xu
0 siblings, 0 replies; only message in thread
From: Like Xu @ 2022-03-09 6:43 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Joao Martins, kvm, Sean Christopherson, Jim Mattson, Wanpeng Li,
Vitaly Kuznetsov, Joerg Roedel, linux-kernel
From: Like Xu <likexu@tencent.com>
Clang warns:
arch/x86/kvm/xen.c:1219:41: warning: right shift count >= width of type [-Wshift-count-overflow]
1219 | (delta > 0 && (uint32_t) (delta >> 50) != 0))) {
| ^~
The delta is long, which is 32-bit on ARCH=i386, hence the overflow
warning. Switch to uint64_t, which is 64-bit and will not overflow.
Fixes: 49c0b9159bce ("KVM: x86/xen: handle PV timers oneshot mode")
Signed-off-by: Like Xu <likexu@tencent.com>
---
arch/x86/kvm/xen.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c
index 8c85a71aa8ca..097181613be5 100644
--- a/arch/x86/kvm/xen.c
+++ b/arch/x86/kvm/xen.c
@@ -1204,7 +1204,7 @@ static bool kvm_xen_hcall_set_timer_op(struct kvm_vcpu *vcpu, uint64_t timeout,
if (timeout) {
uint64_t guest_now = get_kvmclock_ns(vcpu->kvm);
- long delta = timeout - guest_now;
+ uint64_t delta = timeout - guest_now;
/* Xen has a 'Linux workaround' in do_set_timer_op() which
* checks for negative absolute timeout values (caused by
--
2.35.1
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