Re: [PATCH v1 13/14] iommu/arm-smmu-v3: Add CMDQ_OP_TLBI_NH_VAA and CMDQ_OP_TLBI_NH_ALL

Nicolin Chen
2023-03-10T01:20:22Z

On Thu, Mar 09, 2023 at 01:44:34PM +0000, Robin Murphy wrote:
> External email: Use caution opening links or attachments
>
>
> On 2023-03-09 10:53, Nicolin Chen wrote:
> > With a nested translation setup, a stage-1 Context Descriptor table can be
> > managed by a guest OS in the user space. So, the kernel driver should not
> > assume that the guest OS will use a user space device driver that doesn't
> > support TLBI_NH_VAA and TLBI_NH_ALL commands.
> >
> > Add them in the arm_smmu_cmdq_build_cmd(), to prepare for support of these
> > two TLBI invalidation requests from the guest level.
> >
> > Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
> > ---
> > drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 4 ++++
> > drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h | 2 ++
> > 2 files changed, 6 insertions(+)
> >
> > diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> > index 1f318b5e0921..ac63185ae268 100644
> > --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> > +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> > @@ -277,6 +277,9 @@ static int arm_smmu_cmdq_build_cmd(u64 *cmd, struct arm_smmu_cmdq_ent *ent)
> > /* Cover the entire SID range */
> > cmd[1] |= FIELD_PREP(CMDQ_CFGI_1_RANGE, 31);
> > break;
> > + case CMDQ_OP_TLBI_NH_VAA:
> > + ent->tlbi.asid = 0;
>
> This is backwards - NH_VA is a superset of NH_VAA (not to mention that
> quietly modifying the input argument is ugly; in fact it might be nice
> if ent was const here).

I see.

> Please follow the existing pattern, and decouple NH_VA from EL2_VA if
> necessary.

OK. I was trying to keep it neat, but it looks like decoupling
is the right way.

Thanks
Nic