Re: [PATCH] iommu: PGTABLE_LPAE is also for RISCV

[Robin Murphy]

On 2023-03-30 08:31, Geert Uytterhoeven wrote:
> Hi Conor,
>
> On Thu, Mar 30, 2023 at 8:25 AM Conor Dooley <conor.dooley@xxxxxxxxxxxxx> wrote:
> > On Wed, Mar 29, 2023 at 11:01:05PM -0700, Randy Dunlap wrote:
> > > On riscv64, linux-next-20233030 (and for several days earlier),
> > > there is a kconfig warning:
> > >
> > > WARNING: unmet direct dependencies detected for IOMMU_IO_PGTABLE_LPAE
> > >    Depends on [n]: IOMMU_SUPPORT [=y] && (ARM || ARM64 || COMPILE_TEST [=n]) && !GENERIC_ATOMIC64 [=n]
> > >    Selected by [y]:
> > >    - IPMMU_VMSA [=y] && IOMMU_SUPPORT [=y] && (ARCH_RENESAS [=y] || COMPILE_TEST [=n]) && !GENERIC_ATOMIC64 [=n]
> > >
> > > and build errors:
> > >
> > > riscv64-linux-ld: drivers/iommu/io-pgtable-arm.o: in function `.L140':
> > > io-pgtable-arm.c:(.init.text+0x1e8): undefined reference to `alloc_io_pgtable_ops'
> > > riscv64-linux-ld: drivers/iommu/io-pgtable-arm.o: in function `.L168':
> > > io-pgtable-arm.c:(.init.text+0xab0): undefined reference to `free_io_pgtable_ops'
> > > riscv64-linux-ld: drivers/iommu/ipmmu-vmsa.o: in function `.L140':
> > > ipmmu-vmsa.c:(.text+0xbc4): undefined reference to `free_io_pgtable_ops'
> > > riscv64-linux-ld: drivers/iommu/ipmmu-vmsa.o: in function `.L0 ':
> > > ipmmu-vmsa.c:(.text+0x145e): undefined reference to `alloc_io_pgtable_ops'
> > >
> > > Add RISCV as an allowed ARCH dependency to fix these problems.
> > >
> > > Fixes: d286a58bc8f4 ("iommu: Tidy up io-pgtable dependencies")
> > > Signed-off-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
> > > Cc: Joerg Roedel <joro@xxxxxxxxxx>
> > > Cc: Will Deacon <will@xxxxxxxxxx>
> > > Cc: Robin Murphy <robin.murphy@xxxxxxx>
> > > Cc: iommu@xxxxxxxxxxxxxxx
> > > Cc: Conor Dooley <conor@xxxxxxxxxx>
> > > Cc: linux-riscv@xxxxxxxxxxxxxxxxxxx
> > > ---
> > >   drivers/iommu/Kconfig |    2 +-
> > >   1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff -- a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
> > > --- a/drivers/iommu/Kconfig
> > > +++ b/drivers/iommu/Kconfig
> > > @@ -32,7 +32,7 @@ config IOMMU_IO_PGTABLE
> > >   config IOMMU_IO_PGTABLE_LPAE
> > >        bool "ARMv7/v8 Long Descriptor Format"
> >
> > I'm probably missing something here, but why would we want to enable
> > "ARMv7/v8 Long Descriptor Format" on RISC-V?
>
> Indeed, we should not enable it, unless compile-testing.
>
> > Would it not be better to make the Renesas depend on, rather than
> > select the option? It does seem highly arch specific, and I feel like
> > Geert previously mentioned that the RZ/Five (their RISC-V offering)
> > didn't use it.
>
> I think the IPMMU_VMSA dependency should gain
>
>          depends on ARM || ARM64 || COMPILE_TEST

Indeed, I thought we'd settled on something like that in the previous 
thread(s) on ARCH_RENESAS vs. RV32, but I guess nobody got round to 
actually respininng the patch (possibly since my refactoring here ended 
up papering over the immediate RV32 issue).

Cheers,
Robin.

> > >        select IOMMU_IO_PGTABLE
> > > -     depends on ARM || ARM64 || COMPILE_TEST
> > > +     depends on ARM || ARM64 || RISCV || COMPILE_TEST
> > >        depends on !GENERIC_ATOMIC64    # for cmpxchg64()
> > >        help
> > >          Enable support for the ARM long descriptor pagetable format.
>
> Gr{oetje,eeting}s,
>
>                          Geert