Just in case someone re-mounted /sys/fs/resctrl with different mount options (cdp), add a check here. Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1540780 Signed-off-by: Martin Kletzander <mkletzan(a)redhat.com&gt; --- src/util/virresctrl.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/src/util/virresctrl.c b/src/util/virresctrl.c index ef388757a704..6860e86e649d 100644 --- a/src/util/virresctrl.c +++ b/src/util/virresctrl.c @@ -941,6 +941,17 @@ virResctrlAllocParseProcessCache(virResctrlInfoPtr resctrl, if (!mask) return -1; + if (!resctrl || + level >= resctrl->nlevels || + !resctrl->levels[level] || + !resctrl->levels[level]->types[type]) {

On Fri, Feb 02, 2018 at 06:02:22PM +0100, Peter Krempa wrote: > On Fri, Feb 02, 2018 at 15:27:21 +0100, Martin Kletzander wrote: > > Just in case someone re-mounted /sys/fs/resctrl with different mount > > options (cdp), add a check here. > > > > Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1540780 > > > > Signed-off-by: Martin Kletzander <mkletzan(a)redhat.com&gt; > > --- > > src/util/virresctrl.c | 11 +++++++++++ > > 1 file changed, 11 insertions(+) > > > > diff --git a/src/util/virresctrl.c b/src/util/virresctrl.c > > index ef388757a704..6860e86e649d 100644 > > --- a/src/util/virresctrl.c > > +++ b/src/util/virresctrl.c > > @@ -941,6 +941,17 @@ virResctrlAllocParseProcessCache(virResctrlInfoPtr resctrl, > > if (!mask) > > return -1; > > > > + if (!resctrl || > > + level >= resctrl->nlevels || > > + !resctrl->levels[level] || > > + !resctrl->levels[level]->types[type]) { > > The only caller of this function checks the range of type by converting > it from string with 'virResctrlTypeFromString' but the type in this > function is 'virCacheType' and you use 'virCacheTypeToString'. > > Given the inconsistency and the fact that C will not validate the passed > type in this case you should also validate that 'type' has the correct > range. > > ACK with that check added. There are three "inconsistent" types, but they all use VIR_CACHE_TYPE_LAST in their VIR_ENUM_IMPL: - virResctrl - That's the naming we need to use when writing into resctrl schemata file - virCache - That's the naming that was decide upstream that we should use in our XML - virCacheKernel - That's what kernel uses when we read from cache info from sysfs I have no problem with adding one extra check here, but I think this is taken care of by the fact that they all use the same enum for the implementation. I can just extract the const char * fromt he error message before the check and just add `str != NULL` in the condition. I'll leave that choice up to you. I agree the code is not as nice as it could be and I'm already working on at least the minimal refactoring that needs tobe done, but in the meantime I'd like to have this working at least. The number of workarounds we need to make due to IMNSHO poor implementation of resctrl in kernel is sickening^Wtiring let's say. Just so we don't misunderstand each other, I'm not against any changes to that code. Feel free to suggest any other things that might be made better, I'm all for making this nicer. It's just that most of the time I couldn't find any nicer way to do some of these _suboptimal_ things.

Since one of the things in capabilities (info from resctrl updated with data about caches) can be change on the system by remounting the /sys/fs/resctrl with different options, the capabilities need to be refreshed. There is a better fix in the works, but it's going to be way bigger than this (hence the XXX note there), so for the time being let's workaround this. And in order not to slow down the domain starting, only get the capabilities if there are any cachetunes. Relates-to: https://bugzilla.redhat.com/show_bug.cgi?id=1540780 Signed-off-by: Martin Kletzander <mkletzan(a)redhat.com&gt; --- src/qemu/qemu_process.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c index 5a364730c8c1..2ab242b7634d 100644 --- a/src/qemu/qemu_process.c +++ b/src/qemu/qemu_process.c @@ -2514,9 +2514,15 @@ qemuProcessResctrlCreate(virQEMUDriverPtr driver, { int ret = -1; size_t i = 0; - virCapsPtr caps = virQEMUDriverGetCapabilities(driver, false); + virCapsPtr caps = NULL; qemuDomainObjPrivatePtr priv = vm->privateData; + if (!vm->def->ncachetunes) + return 0; + + /* Force capability refresh since resctrl info can change + * XXX: move cache info into virresctrl so caps are not needed */ + caps = virQEMUDriverGetCapabilities(driver, true);

On Fri, Feb 02, 2018 at 06:05:56PM +0100, Peter Krempa wrote: > On Fri, Feb 02, 2018 at 15:27:22 +0100, Martin Kletzander wrote: > > Since one of the things in capabilities (info from resctrl updated with data > > about caches) can be change on the system by remounting the /sys/fs/resctrl with > > different options, the capabilities need to be refreshed. There is a better fix > > in the works, but it's going to be way bigger than this (hence the XXX note > > there), so for the time being let's workaround this. And in order not to slow > > down the domain starting, only get the capabilities if there are any cachetunes. > > > > Relates-to: https://bugzilla.redhat.com/show_bug.cgi?id=1540780 > > > > Signed-off-by: Martin Kletzander <mkletzan(a)redhat.com&gt; > > --- > > src/qemu/qemu_process.c | 8 +++++++- > > 1 file changed, 7 insertions(+), 1 deletion(-) > > > > diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c > > index 5a364730c8c1..2ab242b7634d 100644 > > --- a/src/qemu/qemu_process.c > > +++ b/src/qemu/qemu_process.c > > @@ -2514,9 +2514,15 @@ qemuProcessResctrlCreate(virQEMUDriverPtr driver, > > { > > int ret = -1; > > size_t i = 0; > > - virCapsPtr caps = virQEMUDriverGetCapabilities(driver, false); > > + virCapsPtr caps = NULL; > > qemuDomainObjPrivatePtr priv = vm->privateData; > > > > + if (!vm->def->ncachetunes) > > + return 0; > > + > > + /* Force capability refresh since resctrl info can change > > + * XXX: move cache info into virresctrl so caps are not needed */ > > + caps = virQEMUDriverGetCapabilities(driver, true); > > I hope that your upcoming fix will also deal with the hugepage and NUMa > data which is more often used than this. > Actually, it will just deal with resctrl info being as consistent as possible. I mean you can always remount the directory between libvirtd reading the two files, there will always be a window of opportunity. The fix I have in mind (and code) is just going to make rid of the capability usage from the driver in resctrl-related code. Do you have any pointers to the numa and hugepage faults that we ought to fix?

Maybe it can be dealt with the same way.

> My feelings towards doing this are slightly mixed, but ACK Thanks, pinky swear that I'll remove it in near future ;)