Messages in this thread | | | Date | Tue, 14 Jun 2022 16:12:11 -0500 | From | Steve Wahl <> | Subject | Re: [PATCH v2] iommu/vt-d: Make DMAR_UNITS_SUPPORTED a config setting |
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On Tue, Jun 14, 2022 at 12:01:45PM -0700, Jerry Snitselaar wrote: > On Tue, Jun 14, 2022 at 11:45:35AM -0500, Steve Wahl wrote: > > On Tue, Jun 14, 2022 at 10:21:29AM +0800, Baolu Lu wrote: > > > On 2022/6/14 09:54, Jerry Snitselaar wrote: > > > > On Mon, Jun 13, 2022 at 6:51 PM Baolu Lu <baolu.lu@linux.intel.com> wrote: > > > > > > > > > > On 2022/6/14 09:44, Jerry Snitselaar wrote: > > > > > > On Mon, Jun 13, 2022 at 6:36 PM Baolu Lu<baolu.lu@linux.intel.com> wrote: > > > > > > > On 2022/6/14 04:57, Jerry Snitselaar wrote: > > > > > > > > On Thu, May 12, 2022 at 10:13:09AM -0500, Steve Wahl wrote: > > > > > > > > > To support up to 64 sockets with 10 DMAR units each (640), make the > > > > > > > > > value of DMAR_UNITS_SUPPORTED adjustable by a config variable, > > > > > > > > > CONFIG_DMAR_UNITS_SUPPORTED, and make it's default 1024 when MAXSMP is > > > > > > > > > set. > > > > > > > > > > > > > > > > > > If the available hardware exceeds DMAR_UNITS_SUPPORTED (previously set > > > > > > > > > to MAX_IO_APICS, or 128), it causes these messages: "DMAR: Failed to > > > > > > > > > allocate seq_id", "DMAR: Parse DMAR table failure.", and "x2apic: IRQ > > > > > > > > > remapping doesn't support X2APIC mode x2apic disabled"; and the system > > > > > > > > > fails to boot properly. > > > > > > > > > > > > > > > > > > Signed-off-by: Steve Wahl<steve.wahl@hpe.com> > > > > > > > > > --- > > > > > > > > > > > > > > > > > > Note that we could not find a reason for connecting > > > > > > > > > DMAR_UNITS_SUPPORTED to MAX_IO_APICS as was done previously. Perhaps > > > > > > > > > it seemed like the two would continue to match on earlier processors. > > > > > > > > > There doesn't appear to be kernel code that assumes that the value of > > > > > > > > > one is related to the other. > > > > > > > > > > > > > > > > > > v2: Make this value a config option, rather than a fixed constant. The default > > > > > > > > > values should match previous configuration except in the MAXSMP case. Keeping the > > > > > > > > > value at a power of two was requested by Kevin Tian. > > > > > > > > > > > > > > > > > > drivers/iommu/intel/Kconfig | 6 ++++++ > > > > > > > > > include/linux/dmar.h | 6 +----- > > > > > > > > > 2 files changed, 7 insertions(+), 5 deletions(-) > > > > > > > > > > > > > > > > > > diff --git a/drivers/iommu/intel/Kconfig b/drivers/iommu/intel/Kconfig > > > > > > > > > index 247d0f2d5fdf..fdbda77ac21e 100644 > > > > > > > > > --- a/drivers/iommu/intel/Kconfig > > > > > > > > > +++ b/drivers/iommu/intel/Kconfig > > > > > > > > > @@ -9,6 +9,12 @@ config DMAR_PERF > > > > > > > > > config DMAR_DEBUG > > > > > > > > > bool > > > > > > > > > > > > > > > > > > +config DMAR_UNITS_SUPPORTED > > > > > > > > > + int "Number of DMA Remapping Units supported" > > > > > > > > Also, should there be a "depends on (X86 || IA64)" here? > > > > > > > Do you have any compilation errors or warnings? > > > > > > > > > > > > > > Best regards, > > > > > > > baolu > > > > > > > > > > > > > I think it is probably harmless since it doesn't get used elsewhere, > > > > > > but our tooling was complaining to me because DMAR_UNITS_SUPPORTED was > > > > > > being autogenerated into the configs for the non-x86 architectures we > > > > > > build (aarch64, s390x, ppcle64). > > > > > > We have files corresponding to the config options that it looks at, > > > > > > and I had one for x86 and not the others so it noticed the > > > > > > discrepancy. > > > > > > > > > > So with "depends on (X86 || IA64)", that tool doesn't complain anymore, > > > > > right? > > > > > > > > > > Best regards, > > > > > baolu > > > > > > > > > > > > > Yes, with the depends it no longer happens. > > > > > > The dmar code only exists on X86 and IA64 arch's. Adding this depending > > > makes sense to me. I will add it if no objections. > > > > I think that works after Baolu's patchset that makes intel-iommu.h > > private. I'm pretty sure it wouldn't have worked before that. > > > > No objections. > > > > Yes, I think applying it with the depends prior to Baolu's change would > still run into the issue from the KTR report if someone compiled without > INTEL_IOMMU enabled. > > This was dealing with being able to do something like: > > make allmodconfig ARCH=arm64 ; grep DMAR_UNITS .config > > and finding CONFIG_DMAR_UNITS_SUPPORTED=64. > > Thinking some more though, instead of the depends being on the arch > would depending on DMAR_TABLE or INTEL_IOMMU be more appropriate?
At least in my limited exploration, depending on INTEL_IOMMU yields compile errors, but depending upon DMAR_TABLE appears to work fine.
--> Steve
-- Steve Wahl, Hewlett Packard Enterprise
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