Re: [libvirt] [PATCH v2] tools/virt-host-validate: Fix IOMMU check on s390x

On 3/1/19 12:10 PM, Thomas Huth wrote: > 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; > --- >   v2: >   - Use virDirOpen() + virDirRead() instead of stat() - this should > hopefully >     work now as expected. > >   tools/virt-host-validate-common.c | 22 +++++++++++++++++----- >   1 file changed, 17 insertions(+), 5 deletions(-) > > diff --git a/tools/virt-host-validate-common.c > b/tools/virt-host-validate-common.c > index 73e3bdb..e27b558 100644 > --- a/tools/virt-host-validate-common.c > +++ b/tools/virt-host-validate-common.c > @@ -337,7 +337,12 @@ 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; > +    virArch arch = virArchFromHost(); > +    struct dirent *dent; > +    DIR *dir; > +    int rc; > + >       flags = virHostValidateGetCPUFlags(); >         if (flags && virBitmapIsBitSet(flags, > VIR_HOST_VALIDATE_CPU_FLAG_VMX)) > @@ -347,8 +352,6 @@ int virHostValidateIOMMU(const char *hvname, >         virBitmapFree(flags); >   -    isPPC = ARCH_IS_PPC64(virArchFromHost()); > - >       if (isIntel) { >           virHostMsgCheck(hvname, "%s", _("for device assignment IOMMU > support")); >           if (access("/sys/firmware/acpi/tables/DMAR", F_OK) == 0) { > @@ -373,8 +376,17 @@ int virHostValidateIOMMU(const char *hvname, >                              "hardware platform"); >               return -1; >           } > -    } else if (isPPC) { > +    } else if (ARCH_IS_PPC64(arch)) { >           /* Empty Block */ > +    } else if (ARCH_IS_S390(arch)) { > +        /* On s390x, we skip the IOMMU check if there are no PCI devices > +         * (which is quite usual on s390x) */ > +        if (!virDirOpen(&dir, "/sys/bus/pci/devices")) > +            return 0; > +        rc = virDirRead(dir, &dent, NULL); > +        VIR_DIR_CLOSE(dir); Is this diropen and dirread really necessary?

I mean, would something like plain test of the path presence be okay, e.g. virFileExists("/sys/bus/pci/devices").