linux-kernel - Re: [PATCH v2 2/2] KVM: x86: fix underflow in TSC deadline calculation

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Message-ID: <e543aba8-cd44-6de0-8dae-2d060373e84c@redhat.com>
Date:	Wed, 29 Jun 2016 22:49:07 +0200
From:	Paolo Bonzini <pbonzini@...hat.com>
To:	yunhong jiang <yunhong.jiang@...ux.intel.com>,
	Wanpeng Li <kernellwp@...il.com>
Cc:	linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
	Wanpeng Li <wanpeng.li@...mail.com>,
	Radim Krčmář <rkrcmar@...hat.com>,
	Yunhong Jiang <yunhong.jiang@...el.com>
Subject: Re: [PATCH v2 2/2] KVM: x86: fix underflow in TSC deadline
 calculation



On 29/06/2016 19:16, yunhong jiang wrote:
>> > +		start_sw_tscdeadline(apic);
> IMHO, it's not good to start_sw_tscdeadline() on the start_hv_tscdeadline()
> function. I think it's expected that the sw_timer is stopped when
> start_hv_tscdeadline() returns successsfully, or sw_timer is not impacted if
> start_hv_tscdeadline() fails. But it's not expected that start_hv_tscdeadline()
> returns successfully while in fact it's the sw_timer started instead :)
> 
> Would it be better to simply return failure here, and the caller then
> starts the sw_timer?

I agree with Yunhong.

Paolo