From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:44008) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ceobS-0003i8-AF for qemu-devel@nongnu.org; Fri, 17 Feb 2017 14:54:03 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ceobN-0005AK-I0 for qemu-devel@nongnu.org; Fri, 17 Feb 2017 14:54:02 -0500 Received: from mail.kernel.org ([198.145.29.136]:34142) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1ceobN-00059H-Bi for qemu-devel@nongnu.org; Fri, 17 Feb 2017 14:53:57 -0500 Date: Fri, 17 Feb 2017 21:53:53 +0200 From: "Michael S. Tsirkin" Message-ID: <1487361200-29966-2-git-send-email-mst@redhat.com> References: <1487361200-29966-1-git-send-email-mst@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1487361200-29966-1-git-send-email-mst@redhat.com> Subject: [Qemu-devel] [PULL 01/23] pci/pcie: don't assume cap id 0 is reserved List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Peter Maydell , Peter Xu , Alex Williamson , Marcel Apfelbaum VFIO actually wants to create a capability with ID == 0. This is done to make guest drivers skip the given capability. pcie_add_capability then trips up on this capability when looking for end of capability list. To support this use-case, it's easy enough to switch to e.g. 0xffffffff for these comparisons - we can be sure it will never match a 16-bit capability ID. Signed-off-by: Michael S. Tsirkin Reviewed-by: Peter Xu Reviewed-by: Alex Williamson --- hw/pci/pcie.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/hw/pci/pcie.c b/hw/pci/pcie.c index cbd4bb4..f4dd177 100644 --- a/hw/pci/pcie.c +++ b/hw/pci/pcie.c @@ -610,7 +610,8 @@ bool pcie_cap_is_arifwd_enabled(const PCIDevice *dev) * uint16_t ext_cap_size */ -static uint16_t pcie_find_capability_list(PCIDevice *dev, uint16_t cap_id, +/* Passing a cap_id value > 0xffff will return 0 and put end of list in prev */ +static uint16_t pcie_find_capability_list(PCIDevice *dev, uint32_t cap_id, uint16_t *prev_p) { uint16_t prev = 0; @@ -679,9 +680,11 @@ void pcie_add_capability(PCIDevice *dev, } else { uint16_t prev; - /* 0 is reserved cap id. use internally to find the last capability - in the linked list */ - next = pcie_find_capability_list(dev, 0, &prev); + /* + * 0xffffffff is not a valid cap id (it's a 16 bit field). use + * internally to find the last capability in the linked list. + */ + next = pcie_find_capability_list(dev, 0xffffffff, &prev); assert(prev >= PCI_CONFIG_SPACE_SIZE); assert(next == 0); -- MST