[Qemu-devel] [PULL 0/3] VFIO updates 2017-02-23

[Qemu-devel] [PULL 0/3] VFIO updates 2017-02-23

[Alex Williamson]

The following changes since commit 796b288f7be875045670f963ce99991b3c8e96ac:

  Merge remote-tracking branch 'remotes/cody/tags/block-pull-request' into staging (2017-02-21 15:48:22 +0000)

are available in the git repository at:


  git://github.com/awilliam/qemu-vfio.git tags/vfio-updates-20170223.0

for you to fetch changes up to c2b2e158cc7b1cb431bd6039824ec13c3184a775:

  vfio/pci-quirks.c: Disable stolen memory for igd VFIO (2017-02-22 13:19:59 -0700)

----------------------------------------------------------------
VFIO updates 2017-02-23

 - Report qdev_unplug errors (Alex Williamson)
 - Fix ecap ID 0 handling, improve comment (Alex Williamson)
 - Disable IGD stolen memory in UPT mode too (Xiong Zhang)

----------------------------------------------------------------
Alex Williamson (2):
      vfio/pci: Report errors from qdev_unplug() via device request
      vfio/pci: Improve extended capability comments, skip masked caps

XiongZhang (1):
      vfio/pci-quirks.c: Disable stolen memory for igd VFIO

 hw/vfio/pci-quirks.c | 65 ++++++++++++++++++++++++++++++----------------------
 hw/vfio/pci.c        | 37 +++++++++++++++++++++---------
 2 files changed, 64 insertions(+), 38 deletions(-)

[Qemu-devel] [PULL 1/3] vfio/pci: Report errors from qdev_unplug() via device request

[Alex Williamson]

Currently we ignore this error, report it with error_reportf_err()

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
---
 hw/vfio/pci.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index 332f41d6627f..f2ba9b6cfafc 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -2506,12 +2506,16 @@ static void vfio_unregister_err_notifier(VFIOPCIDevice *vdev)
 static void vfio_req_notifier_handler(void *opaque)
 {
     VFIOPCIDevice *vdev = opaque;
+    Error *err = NULL;
 
     if (!event_notifier_test_and_clear(&vdev->req_notifier)) {
         return;
     }
 
-    qdev_unplug(&vdev->pdev.qdev, NULL);
+    qdev_unplug(&vdev->pdev.qdev, &err);
+    if (err) {
+        error_reportf_err(err, WARN_PREFIX, vdev->vbasedev.name);
+    }
 }
 
 static void vfio_register_req_notifier(VFIOPCIDevice *vdev)

[Qemu-devel] [PULL 2/3] vfio/pci: Improve extended capability comments, skip masked caps

[Alex Williamson]

Since commit 4bb571d857d9 ("pci/pcie: don't assume cap id 0 is
reserved") removes the internal use of extended capability ID 0, the
comment here becomes invalid.  However, peeling back the onion, the
code is still correct and we still can't seed the capability chain
with ID 0, unless we want to muck with using the version number to
force the header to be non-zero, which is much uglier to deal with.
The comment also now covers some of the subtleties of using cap ID 0,
such as transparently indicating absence of capabilities if none are
added.  This doesn't detract from the correctness of the referenced
commit as vfio in the kernel also uses capability ID zero to mask
capabilties.  In fact, we should skip zero capabilities precisely
because the kernel might also expose such a capability at the head
position and re-introduce the problem.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Tested-by: Peter Xu <peterx@redhat.com>
Reported-by: Jintack Lim <jintack@cs.columbia.edu>
Tested-by: Jintack Lim <jintack@cs.columbia.edu>
---
 hw/vfio/pci.c |   31 +++++++++++++++++++++----------
 1 file changed, 21 insertions(+), 10 deletions(-)

diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index f2ba9b6cfafc..03a3d0154976 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -1880,16 +1880,26 @@ static void vfio_add_ext_cap(VFIOPCIDevice *vdev)
     /*
      * Extended capabilities are chained with each pointing to the next, so we
      * can drop anything other than the head of the chain simply by modifying
-     * the previous next pointer.  For the head of the chain, we can modify the
-     * capability ID to something that cannot match a valid capability.  ID
-     * 0 is reserved for this since absence of capabilities is indicated by
-     * 0 for the ID, version, AND next pointer.  However, pcie_add_capability()
-     * uses ID 0 as reserved for list management and will incorrectly match and
-     * assert if we attempt to pre-load the head of the chain with this ID.
-     * Use ID 0xFFFF temporarily since it is also seems to be reserved in
-     * part for identifying absence of capabilities in a root complex register
-     * block.  If the ID still exists after adding capabilities, switch back to
-     * zero.  We'll mark this entire first dword as emulated for this purpose.
+     * the previous next pointer.  Seed the head of the chain here such that
+     * we can simply skip any capabilities we want to drop below, regardless
+     * of their position in the chain.  If this stub capability still exists
+     * after we add the capabilities we want to expose, update the capability
+     * ID to zero.  Note that we cannot seed with the capability header being
+     * zero as this conflicts with definition of an absent capability chain
+     * and prevents capabilities beyond the head of the list from being added.
+     * By replacing the dummy capability ID with zero after walking the device
+     * chain, we also transparently mark extended capabilities as absent if
+     * no capabilities were added.  Note that the PCIe spec defines an absence
+     * of extended capabilities to be determined by a value of zero for the
+     * capability ID, version, AND next pointer.  A non-zero next pointer
+     * should be sufficient to indicate additional capabilities are present,
+     * which will occur if we call pcie_add_capability() below.  The entire
+     * first dword is emulated to support this.
+     *
+     * NB. The kernel side does similar masking, so be prepared that our
+     * view of the device may also contain a capability ID zero in the head
+     * of the chain.  Skip it for the same reason that we cannot seed the
+     * chain with a zero capability.
      */
     pci_set_long(pdev->config + PCI_CONFIG_SPACE_SIZE,
                  PCI_EXT_CAP(0xFFFF, 0, 0));
@@ -1915,6 +1925,7 @@ static void vfio_add_ext_cap(VFIOPCIDevice *vdev)
                                    PCI_EXT_CAP_NEXT_MASK);
 
         switch (cap_id) {
+        case 0: /* kernel masked capability */
         case PCI_EXT_CAP_ID_SRIOV: /* Read-only VF BARs confuse OVMF */
         case PCI_EXT_CAP_ID_ARI: /* XXX Needs next function virtualization */
             trace_vfio_add_ext_cap_dropped(vdev->vbasedev.name, cap_id, next);

[Qemu-devel] [PULL 3/3] vfio/pci-quirks.c: Disable stolen memory for igd VFIO

[Alex Williamson]

From: XiongZhang <xiong.y.zhang@intel.com>

Regardless of running in UPT or legacy mode, the guest igd
drivers may attempt to use stolen memory, however only legacy
mode has BIOS support for reserving stolen memmory in the
guest VM. We zero out the stolen memory size in all cases,
then guest igd driver won't use stolen memory.
In legacy mode, user could use x-igd-gms option to specify the
amount of stolen memory which will be pre-allocated and reserved
by bios for igd use.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=99028
          https://bugs.freedesktop.org/show_bug.cgi?id=99025

Signed-off-by: Xiong Zhang <xiong.y.zhang@intel.com>
Tested-by: Terrence Xu <terrence.xu@intel.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
---
 hw/vfio/pci-quirks.c |   65 +++++++++++++++++++++++++++++---------------------
 1 file changed, 38 insertions(+), 27 deletions(-)

diff --git a/hw/vfio/pci-quirks.c b/hw/vfio/pci-quirks.c
index e9b493b939db..e995e32deedf 100644
--- a/hw/vfio/pci-quirks.c
+++ b/hw/vfio/pci-quirks.c
@@ -1367,14 +1367,45 @@ static void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int nr)
     uint16_t cmd_orig, cmd;
     Error *err = NULL;
 
+    /* This must be an Intel VGA device. */
+    if (!vfio_pci_is(vdev, PCI_VENDOR_ID_INTEL, PCI_ANY_ID) ||
+        !vfio_is_vga(vdev) || nr != 4) {
+        return;
+    }
+
     /*
-     * This must be an Intel VGA device at address 00:02.0 for us to even
-     * consider enabling legacy mode.  The vBIOS has dependencies on the
-     * PCI bus address.
+     * IGD is not a standard, they like to change their specs often.  We
+     * only attempt to support back to SandBridge and we hope that newer
+     * devices maintain compatibility with generation 8.
      */
-    if (!vfio_pci_is(vdev, PCI_VENDOR_ID_INTEL, PCI_ANY_ID) ||
-        !vfio_is_vga(vdev) || nr != 4 ||
-        &vdev->pdev != pci_find_device(pci_device_root_bus(&vdev->pdev),
+    gen = igd_gen(vdev);
+    if (gen != 6 && gen != 8) {
+        error_report("IGD device %s is unsupported by IGD quirks, "
+                     "try SandyBridge or newer", vdev->vbasedev.name);
+        return;
+    }
+
+    /*
+     * Regardless of running in UPT or legacy mode, the guest graphics
+     * driver may attempt to use stolen memory, however only legacy mode
+     * has BIOS support for reserving stolen memory in the guest VM.
+     * Emulate the GMCH register in all cases and zero out the stolen
+     * memory size here. Legacy mode may request allocation and re-write
+     * this below.
+     */
+    gmch = vfio_pci_read_config(&vdev->pdev, IGD_GMCH, 4);
+    gmch &= ~((gen < 8 ? 0x1f : 0xff) << (gen < 8 ? 3 : 8));
+
+    /* GMCH is read-only, emulated */
+    pci_set_long(vdev->pdev.config + IGD_GMCH, gmch);
+    pci_set_long(vdev->pdev.wmask + IGD_GMCH, 0);
+    pci_set_long(vdev->emulated_config_bits + IGD_GMCH, ~0);
+
+    /*
+     * This must be at address 00:02.0 for us to even onsider enabling
+     * legacy mode.  The vBIOS has dependencies on the PCI bus address.
+     */
+    if (&vdev->pdev != pci_find_device(pci_device_root_bus(&vdev->pdev),
                                        0, PCI_DEVFN(0x2, 0))) {
         return;
     }
@@ -1394,18 +1425,6 @@ static void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int nr)
     }
 
     /*
-     * IGD is not a standard, they like to change their specs often.  We
-     * only attempt to support back to SandBridge and we hope that newer
-     * devices maintain compatibility with generation 8.
-     */
-    gen = igd_gen(vdev);
-    if (gen != 6 && gen != 8) {
-        error_report("IGD device %s is unsupported in legacy mode, "
-                     "try SandyBridge or newer", vdev->vbasedev.name);
-        return;
-    }
-
-    /*
      * Most of what we're doing here is to enable the ROM to run, so if
      * there's no ROM, there's no point in setting up this quirk.
      * NB. We only seem to get BIOS ROMs, so a UEFI VM would need CSM support.
@@ -1460,8 +1479,6 @@ static void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int nr)
         goto out;
     }
 
-    gmch = vfio_pci_read_config(&vdev->pdev, IGD_GMCH, 4);
-
     /*
      * If IGD VGA Disable is clear (expected) and VGA is not already enabled,
      * try to enable it.  Probably shouldn't be using legacy mode without VGA,
@@ -1532,12 +1549,11 @@ static void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int nr)
      * when IVD (IGD VGA Disable) is clear, but the claim is that it's unused,
      * so let's not waste VM memory for it.
      */
-    gmch &= ~((gen < 8 ? 0x1f : 0xff) << (gen < 8 ? 3 : 8));
-
     if (vdev->igd_gms) {
         if (vdev->igd_gms <= 0x10) {
             gms_mb = vdev->igd_gms * 32;
             gmch |= vdev->igd_gms << (gen < 8 ? 3 : 8);
+            pci_set_long(vdev->pdev.config + IGD_GMCH, gmch);
         } else {
             error_report("Unsupported IGD GMS value 0x%x", vdev->igd_gms);
             vdev->igd_gms = 0;
@@ -1557,11 +1573,6 @@ static void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int nr)
     fw_cfg_add_file(fw_cfg_find(), "etc/igd-bdsm-size",
                     bdsm_size, sizeof(*bdsm_size));
 
-    /* GMCH is read-only, emulated */
-    pci_set_long(vdev->pdev.config + IGD_GMCH, gmch);
-    pci_set_long(vdev->pdev.wmask + IGD_GMCH, 0);
-    pci_set_long(vdev->emulated_config_bits + IGD_GMCH, ~0);
-
     /* BDSM is read-write, emulated.  The BIOS needs to be able to write it */
     pci_set_long(vdev->pdev.config + IGD_BDSM, 0);
     pci_set_long(vdev->pdev.wmask + IGD_BDSM, ~0);

Re: [Qemu-devel] [PULL 0/3] VFIO updates 2017-02-23

[Peter Maydell]

On 23 February 2017 at 19:32, Alex Williamson
<alex.williamson@redhat.com> wrote:
> The following changes since commit 796b288f7be875045670f963ce99991b3c8e96ac:
>
>   Merge remote-tracking branch 'remotes/cody/tags/block-pull-request' into staging (2017-02-21 15:48:22 +0000)
>
> are available in the git repository at:
>
>
>   git://github.com/awilliam/qemu-vfio.git tags/vfio-updates-20170223.0
>
> for you to fetch changes up to c2b2e158cc7b1cb431bd6039824ec13c3184a775:
>
>   vfio/pci-quirks.c: Disable stolen memory for igd VFIO (2017-02-22 13:19:59 -0700)
>
> ----------------------------------------------------------------
> VFIO updates 2017-02-23
>
>  - Report qdev_unplug errors (Alex Williamson)
>  - Fix ecap ID 0 handling, improve comment (Alex Williamson)
>  - Disable IGD stolen memory in UPT mode too (Xiong Zhang)
>
> ----------------------------------------------------------------

Applied, thanks.

-- PMM