From: Gleb Natapov <gleb@redhat.com>
To: Marcelo Tosatti <mtosatti@redhat.com>
Cc: "Zhang, Yang Z" <yang.z.zhang@intel.com>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"Tian, Kevin" <kevin.tian@intel.com>
Subject: Re: [PATCH v3 2/4] x86, apicv: add APICv register virtualization support
Date: Thu, 6 Dec 2012 08:45:34 +0200 [thread overview]
Message-ID: <20121206064534.GX19514@redhat.com> (raw)
In-Reply-To: <20121205231140.GB26880@amt.cnet>
On Wed, Dec 05, 2012 at 09:11:40PM -0200, Marcelo Tosatti wrote:
> > >> +static int handle_apic_write(struct kvm_vcpu *vcpu)
> > >> +{
> > >> + unsigned long exit_qualification = vmcs_readl(EXIT_QUALIFICATION);
> > >> + u32 offset = exit_qualification & 0xfff;
> > >> +
> > >> + /* APIC-write VM exit is trap-like and thus no need to adjust IP */
> > >> + return kvm_apic_write_nodecode(vcpu, offset) == 0;
> > >> +}
> > >
> > > Point of return value == 0?
> > if kvm_apic_write_nodecode() handle successfully, it will return zero. Then it will return 1 for this vmexit handle.
> > What's wrong?
>
> If kvm_apic_write_nodecode fails (return 0 for the vmexit handle),
> there is an exit to userspace. Why is that necessary?
kvm_apic_write_nodecode() returns apic_reg_write() value.
apic_reg_write() returns 1 when #GP should be injected if used from
MSR, if used from mmio apic_reg_write() is ignored since errors cannot
be reported to a cpu. Since kvm_apic_write_nodecode() is used for mmio
only make it void and ignore apic_reg_write() return value.
--
Gleb.
next prev parent reply other threads:[~2012-12-06 6:45 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-12-03 7:01 [PATCH v3 0/4] x86, apicv: Add APIC virtualization support Yang Zhang
2012-12-03 7:01 ` [PATCH v3 1/4] x86: PIT connects to pin 2 of IOAPIC Yang Zhang
2012-12-03 9:42 ` Gleb Natapov
2012-12-04 5:32 ` Zhang, Yang Z
2012-12-04 12:55 ` Gleb Natapov
2012-12-05 1:28 ` Zhang, Yang Z
2012-12-03 7:01 ` [PATCH v3 2/4] x86, apicv: add APICv register virtualization support Yang Zhang
2012-12-05 0:29 ` Marcelo Tosatti
2012-12-05 3:17 ` Zhang, Yang Z
2012-12-05 23:11 ` Marcelo Tosatti
2012-12-06 6:45 ` Gleb Natapov [this message]
2012-12-03 7:01 ` [PATCH v3 3/4] x86, apicv: add virtual interrupt delivery support Yang Zhang
2012-12-03 11:37 ` Gleb Natapov
2012-12-04 6:39 ` Zhang, Yang Z
2012-12-04 10:58 ` Gleb Natapov
2012-12-05 1:55 ` Zhang, Yang Z
2012-12-05 5:02 ` Gleb Natapov
2012-12-05 6:02 ` Zhang, Yang Z
2012-12-05 10:18 ` Gleb Natapov
2012-12-05 13:51 ` Zhang, Yang Z
2012-12-05 14:00 ` Gleb Natapov
2012-12-06 2:55 ` Zhang, Yang Z
2012-12-06 7:07 ` Gleb Natapov
2012-12-06 7:16 ` Zhang, Yang Z
2012-12-06 7:19 ` Gleb Natapov
2012-12-06 7:20 ` Zhang, Yang Z
2012-12-04 16:46 ` Michael S. Tsirkin
2012-12-05 2:00 ` Marcelo Tosatti
2012-12-05 3:43 ` Zhang, Yang Z
2012-12-05 11:14 ` Gleb Natapov
2012-12-05 14:16 ` Zhang, Yang Z
2012-12-05 14:34 ` Gleb Natapov
2012-12-06 2:58 ` Zhang, Yang Z
2012-12-05 22:38 ` Marcelo Tosatti
2012-12-06 9:28 ` Gleb Natapov
2012-12-06 11:35 ` Zhang, Yang Z
2012-12-05 22:31 ` Marcelo Tosatti
2012-12-06 3:31 ` Zhang, Yang Z
2012-12-06 5:02 ` Zhang, Yang Z
2012-12-06 6:36 ` Gleb Natapov
2012-12-06 6:56 ` Zhang, Yang Z
2012-12-06 20:08 ` Marcelo Tosatti
2012-12-07 1:00 ` Zhang, Yang Z
2012-12-07 7:28 ` Gleb Natapov
2012-12-03 7:01 ` [PATCH v3 4/4] x86, apicv: add virtual x2apic support Yang Zhang
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