From: Ben Gardon <bgardon@google.com>
To: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: LKML <linux-kernel@vger.kernel.org>, kvm <kvm@vger.kernel.org>,
Cannon Matthews <cannonmatthews@google.com>,
Paolo Bonzini <pbonzini@redhat.com>, Peter Xu <peterx@redhat.com>,
Peter Shier <pshier@google.com>,
Peter Feiner <pfeiner@google.com>,
Junaid Shahid <junaids@google.com>,
Jim Mattson <jmattson@google.com>,
Yulei Zhang <yulei.kernel@gmail.com>,
Wanpeng Li <kernellwp@gmail.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Xiao Guangrong <xiaoguangrong.eric@gmail.com>
Subject: Re: [PATCH 01/22] kvm: mmu: Separate making SPTEs from set_spte
Date: Wed, 30 Sep 2020 16:03:04 -0700 [thread overview]
Message-ID: <CANgfPd9uUFHK8q29YtfQPrtj1hAHWLZAf6SCeVp6YUeHR-z6FA@mail.gmail.com> (raw)
In-Reply-To: <20200930045508.GA29405@linux.intel.com>
On Tue, Sep 29, 2020 at 9:55 PM Sean Christopherson
<sean.j.christopherson@intel.com> wrote:
>
> On Fri, Sep 25, 2020 at 02:22:41PM -0700, Ben Gardon wrote:
> > +static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
> > + unsigned int pte_access, int level,
> > + gfn_t gfn, kvm_pfn_t pfn, bool speculative,
> > + bool can_unsync, bool host_writable)
> > +{
> > + u64 spte = 0;
> > + struct kvm_mmu_page *sp;
> > + int ret = 0;
> > +
> > + if (set_mmio_spte(vcpu, sptep, gfn, pfn, pte_access))
> > + return 0;
> > +
> > + sp = sptep_to_sp(sptep);
> > +
> > + spte = make_spte(vcpu, pte_access, level, gfn, pfn, *sptep, speculative,
> > + can_unsync, host_writable, sp_ad_disabled(sp), &ret);
> > + if (!spte)
> > + return 0;
>
> This is an impossible condition. Well, maybe it's theoretically possible
> if page track is active, with EPT exec-only support (shadow_present_mask is
> zero), and pfn==0. But in that case, returning early is wrong.
>
> Rather than return the spte, what about returning 'ret', passing 'new_spte'
> as a u64 *, and dropping the bail early path? That would also eliminate
> the minor wart of make_spte() relying on the caller to initialize 'ret'.
I agree that would make this much cleaner.
>
> > +
> > + if (spte & PT_WRITABLE_MASK)
> > + kvm_vcpu_mark_page_dirty(vcpu, gfn);
> > +
> > if (mmu_spte_update(sptep, spte))
> > ret |= SET_SPTE_NEED_REMOTE_TLB_FLUSH;
> > return ret;
> > --
> > 2.28.0.709.gb0816b6eb0-goog
> >
next prev parent reply other threads:[~2020-09-30 23:03 UTC|newest]
Thread overview: 105+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-25 21:22 [PATCH 00/22] Introduce the TDP MMU Ben Gardon
2020-09-25 21:22 ` [PATCH 01/22] kvm: mmu: Separate making SPTEs from set_spte Ben Gardon
2020-09-30 4:55 ` Sean Christopherson
2020-09-30 23:03 ` Ben Gardon [this message]
2020-09-25 21:22 ` [PATCH 02/22] kvm: mmu: Introduce tdp_iter Ben Gardon
2020-09-26 0:04 ` Paolo Bonzini
2020-09-30 5:06 ` Sean Christopherson
2020-09-26 0:54 ` Paolo Bonzini
2020-09-30 5:08 ` Sean Christopherson
2020-09-30 5:24 ` Sean Christopherson
2020-09-30 6:24 ` Paolo Bonzini
2020-09-30 23:20 ` Eric van Tassell
2020-09-30 23:34 ` Paolo Bonzini
2020-10-01 0:07 ` Sean Christopherson
2020-09-25 21:22 ` [PATCH 03/22] kvm: mmu: Init / Uninit the TDP MMU Ben Gardon
2020-09-26 0:06 ` Paolo Bonzini
2020-09-30 5:34 ` Sean Christopherson
2020-09-30 18:36 ` Ben Gardon
2020-09-30 16:57 ` Sean Christopherson
2020-09-30 17:39 ` Paolo Bonzini
2020-09-30 18:42 ` Ben Gardon
2020-09-25 21:22 ` [PATCH 04/22] kvm: mmu: Allocate and free TDP MMU roots Ben Gardon
2020-09-30 6:06 ` Sean Christopherson
2020-09-30 6:26 ` Paolo Bonzini
2020-09-30 15:38 ` Sean Christopherson
2020-10-12 22:59 ` Ben Gardon
2020-10-12 23:59 ` Sean Christopherson
2020-09-25 21:22 ` [PATCH 05/22] kvm: mmu: Add functions to handle changed TDP SPTEs Ben Gardon
2020-09-26 0:39 ` Paolo Bonzini
2020-09-28 17:23 ` Paolo Bonzini
2020-09-25 21:22 ` [PATCH 06/22] kvm: mmu: Make address space ID a property of memslots Ben Gardon
2020-09-30 6:10 ` Sean Christopherson
2020-09-30 23:11 ` Ben Gardon
2020-09-25 21:22 ` [PATCH 07/22] kvm: mmu: Support zapping SPTEs in the TDP MMU Ben Gardon
2020-09-26 0:14 ` Paolo Bonzini
2020-09-30 6:15 ` Sean Christopherson
2020-09-30 6:28 ` Paolo Bonzini
2020-09-25 21:22 ` [PATCH 08/22] kvm: mmu: Separate making non-leaf sptes from link_shadow_page Ben Gardon
2020-09-25 21:22 ` [PATCH 09/22] kvm: mmu: Remove disallowed_hugepage_adjust shadow_walk_iterator arg Ben Gardon
2020-09-30 16:19 ` Sean Christopherson
2020-09-25 21:22 ` [PATCH 10/22] kvm: mmu: Add TDP MMU PF handler Ben Gardon
2020-09-26 0:24 ` Paolo Bonzini
2020-09-30 16:37 ` Sean Christopherson
2020-09-30 16:55 ` Paolo Bonzini
2020-09-30 17:37 ` Paolo Bonzini
2020-10-06 22:35 ` Ben Gardon
2020-10-06 22:33 ` Ben Gardon
2020-10-07 20:55 ` Sean Christopherson
2020-09-25 21:22 ` [PATCH 11/22] kvm: mmu: Factor out allocating a new tdp_mmu_page Ben Gardon
2020-09-26 0:22 ` Paolo Bonzini
2020-09-30 18:53 ` Ben Gardon
2020-09-25 21:22 ` [PATCH 12/22] kvm: mmu: Allocate struct kvm_mmu_pages for all pages in TDP MMU Ben Gardon
2020-09-25 21:22 ` [PATCH 13/22] kvm: mmu: Support invalidate range MMU notifier for " Ben Gardon
2020-09-30 17:03 ` Sean Christopherson
2020-09-30 23:15 ` Ben Gardon
2020-09-30 23:24 ` Sean Christopherson
2020-09-30 23:27 ` Ben Gardon
2020-09-25 21:22 ` [PATCH 14/22] kvm: mmu: Add access tracking for tdp_mmu Ben Gardon
2020-09-26 0:32 ` Paolo Bonzini
2020-09-30 17:48 ` Sean Christopherson
2020-10-06 23:38 ` Ben Gardon
2020-09-25 21:22 ` [PATCH 15/22] kvm: mmu: Support changed pte notifier in tdp MMU Ben Gardon
2020-09-26 0:33 ` Paolo Bonzini
2020-09-28 15:11 ` Paolo Bonzini
2020-10-07 16:53 ` Ben Gardon
2020-10-07 17:18 ` Paolo Bonzini
2020-10-07 17:30 ` Ben Gardon
2020-10-07 17:54 ` Paolo Bonzini
2020-09-25 21:22 ` [PATCH 16/22] kvm: mmu: Add dirty logging handler for changed sptes Ben Gardon
2020-09-26 0:45 ` Paolo Bonzini
2020-09-25 21:22 ` [PATCH 17/22] kvm: mmu: Support dirty logging for the TDP MMU Ben Gardon
2020-09-26 1:04 ` Paolo Bonzini
2020-10-08 18:27 ` Ben Gardon
2020-09-29 15:07 ` Paolo Bonzini
2020-09-30 18:04 ` Sean Christopherson
2020-09-30 18:08 ` Paolo Bonzini
2020-09-25 21:22 ` [PATCH 18/22] kvm: mmu: Support disabling dirty logging for the tdp MMU Ben Gardon
2020-09-26 1:09 ` Paolo Bonzini
2020-10-07 16:30 ` Ben Gardon
2020-10-07 17:21 ` Paolo Bonzini
2020-10-07 17:28 ` Ben Gardon
2020-10-07 17:53 ` Paolo Bonzini
2020-09-25 21:22 ` [PATCH 19/22] kvm: mmu: Support write protection for nesting in " Ben Gardon
2020-09-30 18:06 ` Sean Christopherson
2020-09-25 21:23 ` [PATCH 20/22] kvm: mmu: NX largepage recovery for TDP MMU Ben Gardon
2020-09-26 1:14 ` Paolo Bonzini
2020-09-30 22:23 ` Ben Gardon
2020-09-29 18:24 ` Paolo Bonzini
2020-09-30 18:15 ` Sean Christopherson
2020-09-30 19:56 ` Paolo Bonzini
2020-09-30 22:33 ` Ben Gardon
2020-09-30 22:27 ` Ben Gardon
2020-09-25 21:23 ` [PATCH 21/22] kvm: mmu: Support MMIO in the " Ben Gardon
2020-09-30 18:19 ` Sean Christopherson
2020-09-25 21:23 ` [PATCH 22/22] kvm: mmu: Don't clear write flooding count for direct roots Ben Gardon
2020-09-26 1:25 ` Paolo Bonzini
2020-10-05 22:48 ` Ben Gardon
2020-10-05 23:44 ` Sean Christopherson
2020-10-06 16:19 ` Ben Gardon
2020-09-26 1:14 ` [PATCH 00/22] Introduce the TDP MMU Paolo Bonzini
2020-09-28 17:31 ` Paolo Bonzini
2020-09-29 17:40 ` Ben Gardon
2020-09-29 18:10 ` Paolo Bonzini
2020-09-30 6:19 ` Sean Christopherson
2020-09-30 6:30 ` Paolo Bonzini
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