From: Avi Kivity <avi@qumranet.com>
To: Marcelo Tosatti <marcelo@kvack.org>
Cc: kvm-devel@lists.sourceforge.net
Subject: Re: [PATCH 7/8] KVM: MMU: VMX cr3 cache support
Date: Thu, 06 Mar 2008 16:44:26 +0200 [thread overview]
Message-ID: <47D0034A.1040504@qumranet.com> (raw)
In-Reply-To: <20080306141150.GA19266@dmt>
Marcelo Tosatti wrote:
>>
>> Here CR3_TARGET_VALUEx is written.
>> My question is:
>> 1 why is vmcs_writel(CR3_TARGET_VALUE0 + idx*2, cr3); called by
>> vmx_set_cr3(), but not called by mmu_free_roots()?
>>
>
> By clearing guest_cr3 entry of the shared area we avoid the guest from
> using it.
>
> So its unecessary to also clear the corresponding CR3_TARGET_VALUE0
> register.
>
>
>> 2 since "cache" is also mapped to guest OS. Is calling
>> vmcs_writel(CR3_TARGET_VALUE0 + idx*2, cr3); necessary?
>>
>
> As said above, no, because the guest will check
> cache->entry[idx].guest_cr3 before attempting to use a cached host_cr3
> value.
>
Only if you trust the guest.
--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.
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next prev parent reply other threads:[~2008-03-06 14:44 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-03-02 16:31 [PATCH 7/8] KVM: MMU: VMX cr3 cache support Avi Kivity
2008-03-06 13:15 ` Zhao Forrest
2008-03-06 14:11 ` Marcelo Tosatti
2008-03-06 14:44 ` Avi Kivity [this message]
2008-03-06 23:47 ` Marcelo Tosatti
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