[libvirt] [PATCH v2] util: disallow assigning or resetting a pci-bridge device

[Martin Kletzander]

On Wed, Jan 18, 2017 at 07:29:29PM +0530, Shivaprasad G Bhat wrote:
>It is destructive to attempt reset on a pci-bridge, the host can crash.
>The bridges won't contain any guest data and neither they can be
>passed through using vfio/stub. So, no point in allowing a reset on them.
>

Wasn't resetting non-endpoint the only way in some cases when you needed
to passthrough 2 endpoint devices when none of them could be reset?  I
might be very easily wrong, though.

>Signed-off-by: Shivaprasad G Bhat <sbhat at linux.vnet.ibm.com>
>---
> src/util/virhostdev.c |   10 ++++++++++
> src/util/virpci.c     |   11 +++++++++++
> 2 files changed, 21 insertions(+)
>
>diff --git a/src/util/virhostdev.c b/src/util/virhostdev.c
>index 0673afb..16b96f3 100644
>--- a/src/util/virhostdev.c
>+++ b/src/util/virhostdev.c
>@@ -532,6 +532,16 @@ virHostdevPreparePCIDevices(virHostdevManagerPtr mgr,
>         bool strict_acs_check = !!(flags & VIR_HOSTDEV_STRICT_ACS_CHECK);
>         bool usesVFIO = (virPCIDeviceGetStubDriver(pci) == VIR_PCI_STUB_DRIVER_VFIO);
>         struct virHostdevIsPCINodeDeviceUsedData data = { mgr, dom_name, usesVFIO };
>+        int hdrType = -1;
>+
>+        if (virPCIGetHeaderType(pci, &hdrType) < 0)
>+            goto cleanup;
>+
>+        if (hdrType == VIR_PCI_HEADER_PCI_BRIDGE) {
>+            virReportError(VIR_ERR_INTERNAL_ERROR, "%s", _("PCI bridge devices"
>+                           " cannot be assigned to guests"));
>+            goto cleanup;
>+        }
>
>         if (!usesVFIO && !virPCIDeviceIsAssignable(pci, strict_acs_check)) {
>             virReportError(VIR_ERR_OPERATION_INVALID,
>diff --git a/src/util/virpci.c b/src/util/virpci.c
>index 0601f49..f205abf 100644
>--- a/src/util/virpci.c
>+++ b/src/util/virpci.c
>@@ -933,6 +933,17 @@ virPCIDeviceReset(virPCIDevicePtr dev,
>     char *drvName = NULL;
>     int ret = -1;
>     int fd = -1;
>+    int hdrType = -1;
>+
>+    if (virPCIGetHeaderType(dev, &hdrType) < 0)
>+        return -1;
>+
>+    if (hdrType != VIR_PCI_HEADER_ENDPOINT) {
>+        virReportError(VIR_ERR_INTERNAL_ERROR,
>+                       _("Invalid attempt to reset non-endpoint PCI device %s."
>+                         " Only PCI endpoint devices can be reset"), dev->name);
>+        return -1;
>+    }
>
>     if (activeDevs && virPCIDeviceListFind(activeDevs, dev)) {
>         virReportError(VIR_ERR_INTERNAL_ERROR,
>
>--
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