Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Fri, 18 Sep 2020 10:49:06 +0200
From:   Gerd Hoffmann <kraxel@redhat.com>
To:     Sean Christopherson <sean.j.christopherson@intel.com>
Cc:     Vitaly Kuznetsov <vkuznets@redhat.com>,
        Peter Xu <peterx@redhat.com>, kvm@vger.kernel.org,
        Paolo Bonzini <pbonzini@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Michael Tsirkin <mst@redhat.com>,
        Julia Suvorova <jsuvorov@redhat.com>,
        Andy Lutomirski <luto@kernel.org>,
        Andrew Jones <drjones@redhat.com>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 0/3] KVM: x86: KVM_MEM_PCI_HOLE memory
Message-ID: <20200918084906.ja5elzh5zli47mg3@sirius.home.kraxel.org>
References: <20200807141232.402895-1-vkuznets@redhat.com>
 <20200825212526.GC8235@xz-x1>
 <87eenlwoaa.fsf@vitty.brq.redhat.com>
 <20200901200021.GB3053@xz-x1>
 <877dtcpn9z.fsf@vitty.brq.redhat.com>
 <20200904061210.GA22435@sjchrist-ice>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20200904061210.GA22435@sjchrist-ice>
Precedence: bulk

  Hi,

> I see a similar ~8k PCI hole reads with a -kernel boot w/ OVMF.  All but 60
> of those are from pcibios_fixup_peer_bridges(), and all are from the kernel.

pcibios_fixup_peer_bridges() looks at pcibios_last_bus, and that in turn
seems to be set according to the mmconfig size (in
arch/x86/pci/mmconfig-shared.c).

So, maybe we just need to declare a smaller mmconfig window in the acpi
tables, depending on the number of pci busses actually used ...

> If all of the above is true, this can be handled by adding "pci=lastbus=0"

... so we don't need manual quirks like this?

take care,
  Gerd