Re: [libvirt] [PATCH] tools/virt-host-validate: Fix IOMMU check on s390x

With further testing... Thomas Huth <thuth(a)redhat.com&gt; [2019-02-26, 12:02PM +0100]: > When running virt-host-validate on an s390x host, the tool currently > warns that it is "Unknown if this platform has IOMMU support". > We can use the common check for entries in sys/kernel/iommu_groups here, > too, but it only makes sense to check it if there are also PCI devices > available. It's also common on s390x that there are no PCI devices > assigned to the LPAR, and in that case there is no need for the > PCI-related IOMMU, so without PCI devices we should simply skip this > test. > > Signed-off-by: Thomas Huth <thuth(a)redhat.com&gt; > --- > tools/virt-host-validate-common.c | 11 +++++++++-- > 1 file changed, 9 insertions(+), 2 deletions(-) > > diff --git a/tools/virt-host-validate-common.c b/tools/virt-host-validate-common.c > index 73e3bdb..75c7cfc 100644 > --- a/tools/virt-host-validate-common.c > +++ b/tools/virt-host-validate-common.c > @@ -337,7 +337,7 @@ int virHostValidateIOMMU(const char *hvname, > virBitmapPtr flags; > struct stat sb; > const char *bootarg = NULL; > - bool isAMD = false, isIntel = false, isPPC = false; > + bool isAMD = false, isIntel = false, isPPC, isS390; > flags = virHostValidateGetCPUFlags(); > > if (flags && virBitmapIsBitSet(flags, VIR_HOST_VALIDATE_CPU_FLAG_VMX)) > @@ -348,6 +348,7 @@ int virHostValidateIOMMU(const char *hvname, > virBitmapFree(flags); > > isPPC = ARCH_IS_PPC64(virArchFromHost()); > + isS390 = ARCH_IS_S390(virArchFromHost()); > > if (isIntel) { > virHostMsgCheck(hvname, "%s", _("for device assignment IOMMU support")); > @@ -375,6 +376,12 @@ int virHostValidateIOMMU(const char *hvname, > } > } else if (isPPC) { > /* Empty Block */ > + } else if (isS390) { > + /* On s390x, we skip the IOMMU check if there are no PCI devices > + * (which is quite usual on s390x) */ > + if (stat("/sys/bus/pci/devices", &sb) < 0 || !S_ISDIR(sb.st_mode) || > + sb.st_nlink <= 2) ... this doesn't seem to work, no? The files in /sys/bus/pci/devices are actually soft-links and are not counted by stat, am I wrong? At least on my setup with a PCI device and populated sysfs it will still skip the check.