From: Paolo Bonzini <pbonzini@redhat.com>
To: Yu Zhang <yu.c.zhang@linux.intel.com>, Ben Gardon <bgardon@google.com>
Cc: Yan Zhao <yan.y.zhao@intel.com>,
Sean Christopherson <seanjc@google.com>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>
Subject: Re: A question of TDP unloading.
Date: Thu, 29 Jul 2021 11:19:08 +0200 [thread overview]
Message-ID: <dd09360e-436e-4e66-faad-656c8aa9cee2@redhat.com> (raw)
In-Reply-To: <20210729030056.uk644q3eeoux2qfa@linux.intel.com>
On 29/07/21 05:00, Yu Zhang wrote:
>> I have a few questions about these unnecessary tear-downs during boot:
>> 1. How many teardowns did you observe, and how many different roles
>> did they represent? Just thrashing between two roles, or 12 different
>> roles?
> I saw 106 reloadings of the root TDP. Among them, 14 are caused by memslot
> changes. Remaining ones are caused by the context reset from CR0/CR4/EFER
> changes(85 for CR0 changes).
Possibly because CR0/CR4/EFER are changed multiple times on SMM entry
(to go from real mode to protected mode to 32-bit to 64-bit)? But most
of those page tables should be very very small; they probably have only
one page per level. The SMM page tables are very small too, the only
one that is really expensive to rebuild is the main non-SMM EPT.
Paolo
next prev parent reply other threads:[~2021-07-29 9:19 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-27 16:19 A question of TDP unloading Yu Zhang
2021-07-27 18:07 ` Sean Christopherson
2021-07-28 6:56 ` Yu Zhang
2021-07-28 7:25 ` Yan Zhao
2021-07-28 16:23 ` Ben Gardon
2021-07-28 17:23 ` Yu Zhang
2021-07-28 17:55 ` Ben Gardon
2021-07-29 3:00 ` Yu Zhang
2021-07-29 2:58 ` Yan Zhao
2021-07-29 5:17 ` Yu Zhang
2021-07-29 5:17 ` Yan Zhao
2021-07-29 6:34 ` Yan Zhao
2021-07-29 8:48 ` Yan Zhao
2021-07-29 20:40 ` Sean Christopherson
2021-07-29 9:19 ` Paolo Bonzini [this message]
2021-07-29 16:38 ` Yu Zhang
2021-07-28 18:37 ` Sean Christopherson
2021-07-29 3:22 ` Yu Zhang
2021-07-29 21:04 ` Sean Christopherson
2021-07-30 2:42 ` Yu Zhang
2021-07-30 9:42 ` Yu Zhang
2021-07-30 8:22 ` Yu Zhang
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