From: Paolo Bonzini <pbonzini@redhat.com>
To: Sean Christopherson <sean.j.christopherson@intel.com>,
Dan Williams <dan.j.williams@intel.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>,
"Vitaly Kuznetsov" <vkuznets@redhat.com>,
"Wanpeng Li" <wanpengli@tencent.com>,
"Jim Mattson" <jmattson@google.com>,
"Joerg Roedel" <joro@8bytes.org>,
"KVM list" <kvm@vger.kernel.org>,
"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
"Adam Borowski" <kilobyte@angband.pl>,
"David Hildenbrand" <david@redhat.com>
Subject: Re: [PATCH 1/2] KVM: MMU: Do not treat ZONE_DEVICE pages as being reserved
Date: Mon, 11 Nov 2019 20:15:24 +0100 [thread overview]
Message-ID: <707ce7d4-7149-f4c4-c150-801962a3197d@redhat.com> (raw)
In-Reply-To: <20191111182750.GE11805@linux.intel.com>
On 11/11/19 19:27, Sean Christopherson wrote:
>> Thanks for this clarification. I do want to put out though that
>> ZONE_DEVICE pages go idle, they don't get freed. As long as KVM drops
>> its usage on invalidate it's perfectly fine for KVM to operate on idle
>> ZONE_DEVICE pages. The common case is that ZONE_DEVICE pages are
>> accessed and mapped while idle. Only direct-I/O temporarily marks them
>> busy to synchronize with invalidate. KVM obviates that need by
>> coordinating with mmu-notifiers instead.
> Only the KVM MMU, e.g. page fault handler, coordinates via mmu_notifier,
> the kvm_vcpu_map() case would continue using pages across an invalidate.
Yes, and it gets/puts the page correctly.
Paolo
next prev parent reply other threads:[~2019-11-11 19:15 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-06 17:07 [PATCH 0/2] KVM: MMU: Fix a refcount bug with ZONE_DEVICE pages Sean Christopherson
2019-11-06 17:07 ` [PATCH 1/2] KVM: MMU: Do not treat ZONE_DEVICE pages as being reserved Sean Christopherson
2019-11-06 17:14 ` Paolo Bonzini
2019-11-06 17:46 ` Sean Christopherson
2019-11-06 18:04 ` Dan Williams
2019-11-06 20:26 ` Sean Christopherson
2019-11-06 20:34 ` Dan Williams
2019-11-06 21:09 ` Paolo Bonzini
2019-11-06 21:30 ` Sean Christopherson
2019-11-06 23:20 ` Dan Williams
2019-11-06 23:39 ` Sean Christopherson
2019-11-07 0:01 ` Dan Williams
2019-11-07 5:48 ` Dan Williams
2019-11-07 11:12 ` Paolo Bonzini
2019-11-07 15:36 ` Dan Williams
2019-11-07 15:58 ` Sean Christopherson
2019-11-09 1:43 ` Sean Christopherson
2019-11-09 2:00 ` Dan Williams
2019-11-11 18:27 ` Sean Christopherson
2019-11-11 19:15 ` Paolo Bonzini [this message]
2019-11-12 0:51 ` Dan Williams
2019-11-12 10:19 ` Paolo Bonzini
2019-11-12 16:57 ` Sean Christopherson
2019-11-06 17:07 ` [PATCH 2/2] KVM: x86/mmu: Add helper to consolidate huge page promotion Sean Christopherson
2019-11-06 17:22 ` Paolo Bonzini
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