From: Tianyu Lan <lantianyu1986@gmail.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Lan Tianyu <Tianyu.Lan@microsoft.com>,
christoffer.dall@arm.com, marc.zyngier@arm.com,
linux@armlinux.org.uk, catalin.marinas@arm.com,
will.deacon@arm.com, jhogan@kernel.org, ralf@linux-mips.org,
paul.burton@mips.com, paulus@ozlabs.org,
benh@kernel.crashing.org, mpe@ellerman.id.au,
Radim Krcmar <rkrcmar@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
bp@alien8.de, "H. Peter Anvin" <hpa@zytor.com>,
"the arch/x86 maintainers" <x86@kernel.org>,
linux-arm-kernel@lists.infradead.org,
kvmarm@lists.cs.columbia.edu,
"linux-kernel@vger kernel org" <linux-kernel@vger.kernel.org>,
linux-mips@vger.kernel.org, kvm-ppc@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org, kvm <kvm@vger.kernel.org>,
michael.h.kelley@microsoft.com, kys@microsoft.com,
vkuznets@redhat.com
Subject: Re: [PATCH 9/11] KVM/MMU: Flush tlb in the kvm_mmu_write_protect_pt_masked()
Date: Thu, 10 Jan 2019 17:06:25 +0800 [thread overview]
Message-ID: <CAOLK0pz6K90+QOMV2Vmhd3vC2t5+15vmUo0E=2rwax7cGDfxjw@mail.gmail.com> (raw)
In-Reply-To: <7eb0cde4-9436-9719-dd13-caf4ab5083a2@redhat.com>
On Tue, Jan 8, 2019 at 12:26 AM Paolo Bonzini <pbonzini@redhat.com> wrote:
>
> On 04/01/19 09:54, lantianyu1986@gmail.com wrote:
> > rmap_head = __gfn_to_rmap(slot->base_gfn + gfn_offset + __ffs(mask),
> > PT_PAGE_TABLE_LEVEL, slot);
> > - __rmap_write_protect(kvm, rmap_head, false);
> > + flush |= __rmap_write_protect(kvm, rmap_head, false);
> >
> > /* clear the first set bit */
> > mask &= mask - 1;
> > }
> > +
> > + if (flush && kvm_available_flush_tlb_with_range()) {
> > + kvm_flush_remote_tlbs_with_address(kvm,
> > + slot->base_gfn + gfn_offset,
> > + hweight_long(mask));
>
> Mask is zero here, so this probably won't work.
>
> In addition, I suspect calling the hypercall once for every 64 pages is
> not very efficient. Passing a flush list into
> kvm_mmu_write_protect_pt_masked, and flushing in
> kvm_arch_mmu_enable_log_dirty_pt_masked, isn't efficient either because
> kvm_arch_mmu_enable_log_dirty_pt_masked is also called once per word.
>
Yes, this is not efficient.
> I don't have any good ideas, except for moving the whole
> kvm_clear_dirty_log_protect loop into architecture-specific code (which
> is not the direction we want---architectures should share more code, not
> less).
kvm_vm_ioctl_clear_dirty_log/get_dirty_log() is to get/clear dirty log with
memslot as unit. We may just flush tlbs of the affected memslot instead of
entire page table's when range flush is available.
>
> Paolo
>
> > + flush = false;
> > + }
> > +
>
--
Best regards
Tianyu Lan
next prev parent reply other threads:[~2019-01-10 9:06 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-04 8:53 [PATCH 00/11] X86/KVM/Hyper-V: Add HV ept tlb range list flush support in KVM lantianyu1986
2019-01-04 8:53 ` [PATCH 1/11] X86/Hyper-V: Add parameter offset for hyperv_fill_flush_guest_mapping_list() lantianyu1986
2019-01-04 8:53 ` [PATCH 2/11] KVM/VMX: Fill range list in kvm_fill_hv_flush_list_func() lantianyu1986
2019-01-04 8:53 ` [PATCH 3/11] KVM: Add spte's point in the struct kvm_mmu_page lantianyu1986
2019-01-07 16:34 ` Paolo Bonzini
2019-01-04 8:53 ` [PATCH 4/11] KVM/MMU: Introduce tlb flush with range list lantianyu1986
2019-01-07 16:39 ` Paolo Bonzini
2019-01-04 8:53 ` [PATCH 5/11] KVM/MMU: Flush tlb directly in the kvm_mmu_slot_gfn_write_protect() lantianyu1986
2019-01-04 8:54 ` [PATCH 6/11] KVM/MMU: Flush tlb with range list in sync_page() lantianyu1986
[not found] ` <20190104163035.GC11288@linux.intel.com>
2019-01-07 5:13 ` Tianyu Lan
2019-01-07 16:07 ` Paolo Bonzini
2019-01-04 8:54 ` [PATCH 7/11] KVM: Remove redundant check in the kvm_get_dirty_log_protect() lantianyu1986
[not found] ` <20190104155036.GA11288@linux.intel.com>
2019-01-04 21:27 ` Sean Christopherson
2019-01-07 16:20 ` Paolo Bonzini
2019-01-04 8:54 ` [PATCH 8/11] KVM: Make kvm_arch_mmu_enable_log_dirty_pt_masked() return value lantianyu1986
2019-01-04 8:54 ` [PATCH 9/11] KVM/MMU: Flush tlb in the kvm_mmu_write_protect_pt_masked() lantianyu1986
2019-01-07 16:26 ` Paolo Bonzini
2019-01-10 9:06 ` Tianyu Lan [this message]
2019-01-04 8:54 ` [PATCH 10/11] KVM: Add flush parameter for kvm_age_hva() lantianyu1986
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