linux-kernel - RE: [PATCH V2 4/13] KVM/MMU: Flush tlb directly in the kvm_handle_hva

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Date:   Thu, 20 Sep 2018 19:05:35 +0000
From:   "Michael Kelley (EOSG)" <Michael.H.Kelley@...rosoft.com>
To:     Tianyu Lan <Tianyu.Lan@...rosoft.com>
CC:     KY Srinivasan <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "hpa@...or.com" <hpa@...or.com>, "x86@...nel.org" <x86@...nel.org>,
        "pbonzini@...hat.com" <pbonzini@...hat.com>,
        "rkrcmar@...hat.com" <rkrcmar@...hat.com>,
        "devel@...uxdriverproject.org" <devel@...uxdriverproject.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        vkuznets <vkuznets@...hat.com>,
        Jork Loeser <Jork.Loeser@...rosoft.com>
Subject: RE: [PATCH V2 4/13] KVM/MMU: Flush tlb directly in the
 kvm_handle_hva_range()

From: Tianyu Lan  Sent: Thursday, September 20, 2018 7:30 AM
> On 9/20/2018 12:08 AM, Michael Kelley (EOSG) wrote:
> > From: Tianyu Lan  Sent: Monday, September 17, 2018 8:19 PM
> >> +
> >> +			if (ret && kvm_available_flush_tlb_with_range()) {
> >> +				kvm_flush_remote_tlbs_with_address(kvm,
> >> +						gfn_start,
> >> +						gfn_end - gfn_start);
> >
> > Does the above need to be gfn_end - gfn_start + 1?
> 
> The flush range depends on the input parameter frame start and frame end
> of for_each_slot_rmap_range().
> 
>          for_each_slot_rmap_range(memslot, PT_PAGE_TABLE_LEVEL,
>                                   PT_MAX_HUGEPAGE_LEVEL,
>                                   gfn_start, gfn_end - 1,
>                                   &iterator)
>                  ret |= handler(kvm, iterator.rmap, memslot,
>                                 iterator.gfn, iterator.level, data);
> 
> 
> The start is "gfn_start" and the end is "gfn_end - 1". The flush size is
> (gfn_end - 1) - gfn_start + 1 = gfn_end - gfn_start.
> 

Got it.  I agree.

Michael