From: Sean Christopherson <seanjc@google.com>
To: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: linux-kernel@vger.kernel.org, Paolo Bonzini <pbonzini@redhat.com>,
Lai Jiangshan <jiangshan.ljs@antgroup.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
kvm@vger.kernel.org
Subject: Re: [PATCH V2 6/8] kvm: x86/mmu: Remove FNAME(invlpg)
Date: Fri, 10 Feb 2023 01:10:57 +0000 [thread overview]
Message-ID: <Y+WZoXYvacqx/+Yu@google.com> (raw)
In-Reply-To: <20230207155735.2845-7-jiangshanlai@gmail.com>
On Tue, Feb 07, 2023, Lai Jiangshan wrote:
> Use FNAME(sync_spte) to share the code which has a slight semantics
> changed: clean vTLB entry is kept.
...
> +static void __kvm_mmu_invalidate_gva(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
> + gva_t gva, hpa_t root_hpa)
> +{
> + struct kvm_shadow_walk_iterator iterator;
> +
> + vcpu_clear_mmio_info(vcpu, gva);
> +
> + write_lock(&vcpu->kvm->mmu_lock);
> + for_each_shadow_entry_using_root(vcpu, root_hpa, gva, iterator) {
> + struct kvm_mmu_page *sp = sptep_to_sp(iterator.sptep);
> +
> + if (sp->unsync && *iterator.sptep) {
Please make the !0 change in a separate patch. It took me a while to connect the
dots, and to also understand what I suspect is a major motivation: sync_spte()
already has this check, i.e. the change is happening regardless, so might as well
avoid the indirect branch.
> + gfn_t gfn = kvm_mmu_page_get_gfn(sp, iterator.index);
> + int ret = mmu->sync_spte(vcpu, sp, iterator.index);
> +
> + if (ret < 0)
> + mmu_page_zap_pte(vcpu->kvm, sp, iterator.sptep, NULL);
> + if (ret)
> + kvm_flush_remote_tlbs_with_address(vcpu->kvm, gfn, 1);
Why open code kvm_flush_remote_tlbs_sptep()? Does it actually shave enough
cycles to be visible?
If open coding is really justified, can you rebase on one of the two branches?
And then change this to kvm_flush_remote_tlbs_gfn().
https://github.com/kvm-x86/linux/tree/next
https://github.com/kvm-x86/linux/tree/mmu
next prev parent reply other threads:[~2023-02-10 1:11 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-07 15:57 [PATCH V2 0/8] kvm: x86/mmu: Share the same code to invalidate each vTLB entry Lai Jiangshan
2023-02-07 15:57 ` [PATCH V2 1/8] kvm: x86/mmu: Use KVM_MMU_ROOT_XXX for kvm_mmu_invalidate_gva() Lai Jiangshan
2023-02-10 0:50 ` Sean Christopherson
2023-02-07 15:57 ` [PATCH V2 2/8] kvm: x86/mmu: Use kvm_mmu_invalidate_gva() in kvm_mmu_invpcid_gva() Lai Jiangshan
2023-02-07 15:57 ` [PATCH V2 3/8] kvm: x86/mmu: Use kvm_mmu_invalidate_gva() in nested_ept_invalidate_addr() Lai Jiangshan
2023-02-10 0:52 ` Sean Christopherson
2023-02-07 15:57 ` [PATCH V2 4/8] kvm: x86/mmu: Set mmu->sync_page as NULL for direct paging Lai Jiangshan
2023-02-07 16:17 ` Paolo Bonzini
2023-02-10 0:57 ` Sean Christopherson
2023-02-07 15:57 ` [PATCH V2 5/8] kvm: x86/mmu: Move the code out of FNAME(sync_page)'s loop body into mmu.c Lai Jiangshan
2023-02-07 15:57 ` [PATCH V2 6/8] kvm: x86/mmu: Remove FNAME(invlpg) Lai Jiangshan
2023-02-10 1:10 ` Sean Christopherson [this message]
2023-02-16 4:16 ` Lai Jiangshan
2023-02-07 15:57 ` [PATCH V2 7/8] kvm: x86/mmu: Reduce the update to the spte in FNAME(sync_page) Lai Jiangshan
2023-02-07 15:57 ` [PATCH V2 8/8] kvm: x86/mmu: Remove @no_dirty_log from FNAME(prefetch_gpte) Lai Jiangshan
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