From: David Matlack <dmatlack@google.com>
To: Vipin Sharma <vipinsh@google.com>
Cc: seanjc@google.com, pbonzini@redhat.com, bgardon@google.com,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [Patch v3 6/7] KVM: x86/mmu: Remove handle_changed_spte_dirty_log()
Date: Wed, 22 Feb 2023 11:36:16 -0800 [thread overview]
Message-ID: <Y/ZusFTMlUUWsWLF@google.com> (raw)
In-Reply-To: <20230211014626.3659152-7-vipinsh@google.com>
On Fri, Feb 10, 2023 at 05:46:25PM -0800, Vipin Sharma wrote:
> Remove handle_changed_spte_dirty_log() as there is no code flow which
> sets 4KiB SPTE writable and hit this path. This function marks the page
> dirty in a memslot only if new SPTE is 4KiB in size and writable.
>
> Current users of handle_changed_spte_dirty_log() are:
> 1. set_spte_gfn() - Create only non writable SPTEs.
> 2. write_protect_gfn() - Change an SPTE to non writable.
> 3. zap leaf and roots APIs - Everything is 0.
> 4. handle_removed_pt() - Sets SPTEs to REMOVED_SPTE
> 5. tdp_mmu_link_sp() - Makes non leaf SPTEs.
>
> There is also no path which creates a writable 4KiB without going
> through make_spte() and this functions takes care of marking SPTE dirty
> in the memslot if it is PT_WRITABLE.
>
> Signed-off-by: Vipin Sharma <vipinsh@google.com>
Aside from the comment suggestion,
Reviewed-by: David Matlack <dmatlack@google.com>
> ---
> arch/x86/kvm/mmu/tdp_mmu.c | 22 ----------------------
> 1 file changed, 22 deletions(-)
>
> diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
> index e50e869bf879..0c031319e901 100644
> --- a/arch/x86/kvm/mmu/tdp_mmu.c
> +++ b/arch/x86/kvm/mmu/tdp_mmu.c
> @@ -345,24 +345,6 @@ static void handle_changed_spte_acc_track(u64 old_spte, u64 new_spte, int level)
> kvm_set_pfn_accessed(spte_to_pfn(old_spte));
> }
>
> -static void handle_changed_spte_dirty_log(struct kvm *kvm, int as_id, gfn_t gfn,
> - u64 old_spte, u64 new_spte, int level)
> -{
> - bool pfn_changed;
> - struct kvm_memory_slot *slot;
> -
> - if (level > PG_LEVEL_4K)
> - return;
> -
> - pfn_changed = spte_to_pfn(old_spte) != spte_to_pfn(new_spte);
> -
> - if ((!is_writable_pte(old_spte) || pfn_changed) &&
> - is_writable_pte(new_spte)) {
> - slot = __gfn_to_memslot(__kvm_memslots(kvm, as_id), gfn);
> - mark_page_dirty_in_slot(kvm, slot, gfn);
> - }
> -}
> -
> static void tdp_account_mmu_page(struct kvm *kvm, struct kvm_mmu_page *sp)
> {
> kvm_account_pgtable_pages((void *)sp->spt, +1);
> @@ -614,8 +596,6 @@ static void handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn,
> __handle_changed_spte(kvm, as_id, gfn, old_spte, new_spte, level,
> shared);
> handle_changed_spte_acc_track(old_spte, new_spte, level);
> - handle_changed_spte_dirty_log(kvm, as_id, gfn, old_spte,
> - new_spte, level);
Please leave a comment somewhere in handle_changed_spte() to document
why mark_page_dirty_in_slot() is not needed to help future readers and
in case something changes in the future.
next prev parent reply other threads:[~2023-02-22 19:36 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-11 1:46 [Patch v3 0/7] Optimize clear dirty log Vipin Sharma
2023-02-11 1:46 ` [Patch v3 1/7] KVM: x86/mmu: Add a helper function to check if an SPTE needs atomic write Vipin Sharma
2023-02-11 1:46 ` [Patch v3 2/7] KVM: x86/mmu: Atomically clear SPTE dirty state in the clear-dirty-log flow Vipin Sharma
2023-02-15 21:12 ` David Matlack
2023-03-17 22:59 ` Sean Christopherson
2023-03-17 23:50 ` Vipin Sharma
2023-02-11 1:46 ` [Patch v3 3/7] KVM: x86/mmu: Remove "record_dirty_log" in __tdp_mmu_set_spte() Vipin Sharma
2023-02-15 21:10 ` David Matlack
2023-02-11 1:46 ` [Patch v3 4/7] KVM: x86/mmu: Optimize SPTE change for aging gfn range Vipin Sharma
2023-02-15 21:15 ` David Matlack
2023-03-21 0:51 ` Sean Christopherson
2023-02-11 1:46 ` [Patch v3 5/7] KVM: x86/mmu: Remove "record_acc_track" in __tdp_mmu_set_spte() Vipin Sharma
2023-02-22 19:31 ` David Matlack
2023-02-11 1:46 ` [Patch v3 6/7] KVM: x86/mmu: Remove handle_changed_spte_dirty_log() Vipin Sharma
2023-02-22 19:36 ` David Matlack [this message]
2023-02-11 1:46 ` [Patch v3 7/7] KVM: x86/mmu: Merge all handle_changed_pte* functions Vipin Sharma
2023-02-22 19:42 ` David Matlack
2023-03-17 22:51 ` Sean Christopherson
2023-03-17 23:48 ` Vipin Sharma
2023-03-17 22:57 ` [Patch v3 0/7] Optimize clear dirty log Sean Christopherson
2023-03-17 23:51 ` Vipin Sharma
2023-03-21 0:41 ` Sean Christopherson
2023-03-21 18:11 ` Vipin Sharma
2023-03-21 19:57 ` Sean Christopherson
2023-03-21 20:40 ` Sean Christopherson
2023-03-21 21:38 ` Sean Christopherson
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