From: David Matlack <dmatlack@google.com>
To: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
"open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips)"
<kvm@vger.kernel.org>, Paolo Bonzini <pbonzini@redhat.com>,
Sean Christopherson <seanjc@google.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Maxim Levitsky <mlevitsk@redhat.com>,
Lai Jiangshan <jiangshan.ljs@antgroup.com>
Subject: Re: [PATCH V3 00/12] KVM: X86/MMU: Use one-off local shadow page for special roots
Date: Thu, 26 May 2022 20:27:02 +0000 [thread overview]
Message-ID: <Yo/ilj2ll5HJqP+O@google.com> (raw)
In-Reply-To: <CAJhGHyDSxN5haa6bx+44jRXw3PBad6DcmZNc115g5Vfve=xLEA@mail.gmail.com>
On Thu, May 26, 2022 at 04:49:09PM +0800, Lai Jiangshan wrote:
> On Sat, May 21, 2022 at 9:16 PM Lai Jiangshan <jiangshanlai@gmail.com> wrote:
> >
> > From: Lai Jiangshan <jiangshan.ljs@antgroup.com>
> >
> > Current code uses mmu->pae_root, mmu->pml4_root, and mmu->pml5_root to
> > setup special roots. The initialization code is complex and the roots
> > are not associated with struct kvm_mmu_page which causes the code more
> > complex.
> >
> > So add new local shadow pages to simplify it.
> >
> > The local shadow pages are associated with struct kvm_mmu_page and
> > VCPU-local.
> >
> > The local shadow pages are created and freed when the roots are
> > changed (or one-off) which can be optimized but not in the patchset
> > since the re-creating is light way (in normal case only the struct
> > kvm_mmu_page needs to be re-allocated and sp->spt doens't, because
> > it is likely to be mmu->pae_root)
> >
> > The patchset also fixes a possible bug described in:
> > https://lore.kernel.org/lkml/20220415103414.86555-1-jiangshanlai@gmail.com/
> > as patch1.
> >
>
> Ping and please ignore patch1 and patch9. It would not cause any conflict
> without patch1 and patch9 if both are ignored together.
>
> The fix is wrong (see new discussion in the above link). So the possible
> correct fix will not have any conflict with this patchset of one-off
> local shadow page. I don't want to add extra stuff in this patchset
> anymore.
Yeah I agree with splitting this fix out to a separate patchset, and
ordered after this cleanup so it can be done in one patch.
When you get around to it, can you also implement a kvm-unit-test to
demonstrate the bug? It would be good to have a regression test.
>
> Thanks
> Lai
prev parent reply other threads:[~2022-05-26 20:27 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-21 13:16 [PATCH V3 00/12] KVM: X86/MMU: Use one-off local shadow page for special roots Lai Jiangshan
2022-05-21 13:16 ` [PATCH V3 01/12] KVM: X86/MMU: Verify PDPTE for nested NPT in PAE paging mode when page fault Lai Jiangshan
2022-07-19 21:17 ` Sean Christopherson
2022-05-21 13:16 ` [PATCH V3 02/12] KVM: X86/MMU: Add using_local_root_page() Lai Jiangshan
2022-05-26 21:28 ` David Matlack
2022-05-26 21:38 ` Sean Christopherson
2022-07-19 22:03 ` Sean Christopherson
2022-05-21 13:16 ` [PATCH V3 03/12] KVM: X86/MMU: Reduce a check in using_local_root_page() for common cases Lai Jiangshan
2022-05-21 13:16 ` [PATCH V3 04/12] KVM: X86/MMU: Add local shadow pages Lai Jiangshan
2022-05-26 21:38 ` David Matlack
2022-05-26 22:01 ` David Matlack
2022-07-20 0:35 ` Sean Christopherson
2022-05-21 13:16 ` [PATCH V3 05/12] KVM: X86/MMU: Link PAE root pagetable with its children Lai Jiangshan
2022-07-19 22:21 ` Sean Christopherson
2022-05-21 13:16 ` [PATCH V3 06/12] KVM: X86/MMU: Activate local shadow pages and remove old logic Lai Jiangshan
2022-05-21 13:16 ` [PATCH V3 07/12] KVM: X86/MMU: Remove the check of the return value of to_shadow_page() Lai Jiangshan
2022-07-19 22:42 ` Sean Christopherson
2022-05-21 13:16 ` [PATCH V3 08/12] KVM: X86/MMU: Allocate mmu->pae_root for PAE paging on-demand Lai Jiangshan
2022-07-19 23:08 ` Sean Christopherson
2022-07-20 0:07 ` Sean Christopherson
2022-05-21 13:16 ` [PATCH V3 09/12] KVM: X86/MMU: Move the verifying of NPT's PDPTE in FNAME(fetch) Lai Jiangshan
2022-07-19 23:21 ` Sean Christopherson
2022-05-21 13:16 ` [PATCH V3 10/12] KVM: X86/MMU: Remove unused INVALID_PAE_ROOT and IS_VALID_PAE_ROOT Lai Jiangshan
2022-07-19 23:11 ` Sean Christopherson
2022-05-21 13:16 ` [PATCH V3 11/12] KVM: X86/MMU: Don't use mmu->pae_root when shadowing PAE NPT in 64-bit host Lai Jiangshan
2022-07-19 23:26 ` Sean Christopherson
2022-07-19 23:27 ` Sean Christopherson
2022-05-21 13:17 ` [PATCH V3 12/12] KVM: X86/MMU: Remove mmu_alloc_special_roots() Lai Jiangshan
2022-05-26 8:49 ` [PATCH V3 00/12] KVM: X86/MMU: Use one-off local shadow page for special roots Lai Jiangshan
2022-05-26 20:27 ` David Matlack [this message]
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