From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:38659) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cQms6-00078v-BE for qemu-devel@nongnu.org; Mon, 09 Jan 2017 22:13:15 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cQms1-0002To-De for qemu-devel@nongnu.org; Mon, 09 Jan 2017 22:13:14 -0500 Received: from mx1.redhat.com ([209.132.183.28]:49794) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cQms1-0002Td-7f for qemu-devel@nongnu.org; Mon, 09 Jan 2017 22:13:09 -0500 Received: from int-mx11.intmail.prod.int.phx2.redhat.com (int-mx11.intmail.prod.int.phx2.redhat.com [10.5.11.24]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 2ACF94E4C6 for ; Tue, 10 Jan 2017 03:13:09 +0000 (UTC) Date: Tue, 10 Jan 2017 05:13:07 +0200 From: "Michael S. Tsirkin" Message-ID: <20170110051006-mutt-send-email-mst@kernel.org> References: <1483559838-8797-1-git-send-email-marcel@redhat.com> <1483559838-8797-2-git-send-email-marcel@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1483559838-8797-2-git-send-email-marcel@redhat.com> Subject: Re: [Qemu-devel] [PATCH 1/4] hw/pcie: fix Extended Configuration Space for devices with no Extended Capabilities List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Marcel Apfelbaum Cc: qemu-devel@nongnu.org, yvugenfi@redhat.com On Wed, Jan 04, 2017 at 09:57:15PM +0200, Marcel Apfelbaum wrote: > Absence of any Extended Capabilities is required to be > indicated by an Extended Capability header with a Capability ID of > 0000h, a Capability Version of 0h, and a Next Capability Offset of 000h. > > Instead of inserting a 'NULL' capability is simpler to mark the start > of the Extended Configuration Space as read-only to achieve the same > behaviour. > > Signed-off-by: Marcel Apfelbaum Kind of hacky and only theoretical - I don't think any guest writes there - but ok. However I think 1. we should init config to 0 too 2. this needs a compat flag > --- > hw/pci/pcie.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/hw/pci/pcie.c b/hw/pci/pcie.c > index 99cfb45..62c1def 100644 > --- a/hw/pci/pcie.c > +++ b/hw/pci/pcie.c > @@ -109,6 +109,9 @@ int pcie_cap_init(PCIDevice *dev, uint8_t offset, uint8_t type, uint8_t port) > PCI_EXP_DEVCAP2_EFF | PCI_EXP_DEVCAP2_EETLPP); > > pci_set_word(dev->wmask + pos + PCI_EXP_DEVCTL2, PCI_EXP_DEVCTL2_EETLPPB); > + > + /* read-only to behave like a 'NULL' Extended Capability Header */ > + pci_set_long(dev->wmask + PCI_CONFIG_SPACE_SIZE, 0); > return pos; > } > > -- > 2.5.5