From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43940) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YJ0OR-0001wD-VJ for qemu-devel@nongnu.org; Wed, 04 Feb 2015 08:53:24 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YJ0ON-0005um-UT for qemu-devel@nongnu.org; Wed, 04 Feb 2015 08:53:23 -0500 Received: from mx1.redhat.com ([209.132.183.28]:57437) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YJ0ON-0005uW-DW for qemu-devel@nongnu.org; Wed, 04 Feb 2015 08:53:19 -0500 Message-ID: <1423057992.22865.460.camel@redhat.com> From: Alex Williamson Date: Wed, 04 Feb 2015 06:53:12 -0700 In-Reply-To: <54D1EC5F.2020200@cn.fujitsu.com> References: <87dd603bfecae702fc24207300b047937933618b.1422433767.git.chen.fan.fnst@cn.fujitsu.com> <1422908169.22865.420.camel@redhat.com> <54D1EC5F.2020200@cn.fujitsu.com> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [RFC v2 6/8] vfio_pci: fix a wrong check in vfio_pci_reset List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Chen Fan Cc: marcel@redhat.com, izumi.taku@jp.fujitsu.com, qemu-devel@nongnu.org On Wed, 2015-02-04 at 17:54 +0800, Chen Fan wrote: > On 02/03/2015 04:16 AM, Alex Williamson wrote: > > On Wed, 2015-01-28 at 16:37 +0800, Chen Fan wrote: > >> when vfio device support FLR, then when device reset, > >> we call VFIO_DEVICE_RESET ioctl to reset the device first, > >> at kernel side, we also can see the order of reset: > >> 3330 rc = pcie_flr(dev, probe); > >> 3331 if (rc != -ENOTTY) > >> 3332 goto done; > >> 3333 > >> 3334 rc = pci_af_flr(dev, probe); > >> 3335 if (rc != -ENOTTY) > >> 3336 goto done; > >> 3337 > >> 3338 rc = pci_pm_reset(dev, probe); > >> 3339 if (rc != -ENOTTY) > >> 3340 goto done; > >> > >> so when vfio has FLR, reset it directly. > >> > >> Signed-off-by: Chen Fan > >> --- > >> hw/vfio/pci.c | 2 +- > >> 1 file changed, 1 insertion(+), 1 deletion(-) > >> > >> diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c > >> index 8c81bb3..54eb6b4 100644 > >> --- a/hw/vfio/pci.c > >> +++ b/hw/vfio/pci.c > >> @@ -3455,7 +3455,7 @@ static void vfio_pci_reset(DeviceState *dev) > >> vfio_pci_pre_reset(vdev); > >> > >> if (vdev->vbasedev.reset_works && > >> - (vdev->has_flr || !vdev->has_pm_reset) && > >> + vdev->has_flr && > >> !ioctl(vdev->vbasedev.fd, VFIO_DEVICE_RESET)) { > >> trace_vfio_pci_reset_flr(vdev->vbasedev.name); > >> goto post_reset; > > Does this actually fix anything? QEMU shouldn't rely on a specific > > behavior of the kernel. This test is de-prioritizing a PM reset because > > they're often non-effective. If the device supports FLR, the second > > part of the OR is unreached, so what's the point of this change? > For this change, when I tested the code on my own machine. > I found the vfio device has neither flr nor pm reset (e.g. NoSoftRst+). > this also trigger ioctl VFIO_DEVICE_RESET, is it right? Yes, that means that the device has a device specific reset or that it's a singleton device on the bus and we can use the simpler path of VFIO_DEVICE_RESET. Thanks, Alex