On 12/17/21 09:41, cgel.zte@xxxxxxxxx wrote:
From: Changcheng Deng <deng.changcheng@xxxxxxxxxx>
do_div() does a 64-by-32 division. Here the divisor is an unsigned long
which on some platforms is 64 bit wide. So use div64_ul instead of do_div
to avoid a possible truncation.
Reported-by: Zeal Robot <zealci@xxxxxxxxxx>
Signed-off-by: Changcheng Deng <deng.changcheng@xxxxxxxxxx>
---
arch/x86/kvm/lapic.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index c5028e6b0f96..3b629870632c 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1707,7 +1707,7 @@ static void start_sw_tscdeadline(struct kvm_lapic *apic)
guest_tsc = kvm_read_l1_tsc(vcpu, rdtsc());
ns = (tscdeadline - guest_tsc) * 1000000ULL;
- do_div(ns, this_tsc_khz);
+ ns = div64_ul(ns, this_tsc_khz);
if (likely(tscdeadline > guest_tsc) &&
likely(ns > apic->lapic_timer.timer_advance_ns)) {
You could change this_tsc_khz to u32 instead, it's assigned from a
32-bit value.
Using div64_ul would be unnecessary and less efficient.
Paolo
