From: Nadav Amit <nadav.amit@gmail.com>
To: Gleb Natapov <gleb@kernel.org>
Cc: Tang Chen <tangchen@cn.fujitsu.com>,
mtosatti@redhat.com, kvm@vger.kernel.org, laijs@cn.fujitsu.com,
isimatu.yasuaki@jp.fujitsu.com, guz.fnst@cn.fujitsu.com,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 4/4] kvm, mem-hotplug: Update apic access page when it is migrated.
Date: Mon, 07 Jul 2014 15:10:23 +0300 [thread overview]
Message-ID: <53BA8E2F.9000200@gmail.com> (raw)
In-Reply-To: <20140707115446.GP18167@minantech.com>
On 7/7/14, 2:54 PM, Gleb Natapov wrote:
> On Mon, Jul 07, 2014 at 02:42:27PM +0300, Nadav Amit wrote:
>> Tang,
>>
>> Running some (unrelated) tests I see that KVM does not handle APIC base
>> relocation correctly. When the base is changed, kvm_lapic_set_base just
>> changes lapic->base_address without taking further action (i.e., modifying
>> the VMCS apic address in VMX).
>>
>> This patch follows KVM bad behavior by using the constant
>> VMX_APIC_ACCESS_PAGE_ADDR instead of lapic->base_address.
> There is no OS out there that relocates APIC base (in fact it was not always
> relocatable on real HW), so there is not point in complicating the code to support
> it. In fact current APIC_ACCESS_ADDR handling relies on the fact that all vcpus
> has apic mapped at the same address.
>
>>
>> Anyhow, I didn't see anything that would make my life (in fixing the lapic
>> base issue) too difficult. Yet, feel free in making it more "fix-friendly".
>>
> Why would you want to fix it?
>
If there is no general need, I will not send a fix. However, I think the
very least a warning message should be appear if the guest relocates the
APIC base.
Nadav
next prev parent reply other threads:[~2014-07-07 12:10 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-02 9:00 [PATCH 0/4] kvm, mem-hotplug: Do not pin ept identity pagetable and apic access page Tang Chen
2014-07-02 9:00 ` [PATCH 1/4] kvm: Add gfn_to_page_no_pin() Tang Chen
2014-07-02 9:00 ` [PATCH 2/4] kvm: Add macro VMX_APIC_ACCESS_PAGE_ADDR Tang Chen
2014-07-02 16:24 ` Gleb Natapov
2014-07-03 1:19 ` Tang Chen
2014-07-02 9:00 ` [PATCH 3/4] kvm, memory-hotplug: Update ept identity pagetable when it is migrated Tang Chen
2014-07-02 16:34 ` Gleb Natapov
2014-07-03 1:19 ` Tang Chen
2014-07-04 2:36 ` Tang Chen
2014-07-04 9:49 ` Gleb Natapov
2014-07-02 9:00 ` [PATCH 4/4] kvm, mem-hotplug: Update apic access page " Tang Chen
2014-07-03 13:55 ` Gleb Natapov
2014-07-04 2:18 ` Tang Chen
2014-07-04 2:18 ` Tang Chen
2014-07-04 10:13 ` Gleb Natapov
2014-07-07 6:17 ` Tang Chen
2014-07-07 9:52 ` Tang Chen
2014-07-07 11:42 ` Nadav Amit
2014-07-07 11:54 ` Gleb Natapov
2014-07-07 12:10 ` Nadav Amit [this message]
2014-07-07 12:15 ` Gleb Natapov
2014-07-08 1:44 ` Tang Chen
2014-07-08 6:46 ` Nadav Amit
2014-07-07 10:35 ` Wanpeng Li
2014-07-08 9:40 ` Tang Chen
2014-07-03 1:17 ` [PATCH 0/4] kvm, mem-hotplug: Do not pin ept identity pagetable and apic access page Tang Chen
2014-07-03 6:04 ` Gleb Natapov
2014-07-04 6:41 ` Tang Chen
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