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

On 27/02/2019 10.15, Bjoern Walk wrote: > 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. Bummer. Stupid thinko. And I don't have a real PCI card for testing here, so I did not notice. So I guess I have to use opendir() + readdir() instead to find out if there are entries in this directory? Thomas

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