Re: [PATCH v7 3/9] iommu/arm-smmu-v3: Move the CD generation for S1 domains into a function

Mostafa Saleh
2024-04-19T21:11:19Z

Hi Jason,

On Tue, Apr 16, 2024 at 04:28:14PM -0300, Jason Gunthorpe wrote:
> Introduce arm_smmu_make_s1_cd() to build the CD from the paging S1 domain,
> and reorganize all the places programming S1 domain CD table entries to
> call it.
>
> Split arm_smmu_update_s1_domain_cd_entry() from
> arm_smmu_update_ctx_desc_devices() so that the S1 path has its own call
> chain separate from the unrelated SVA path.
>
> arm_smmu_update_s1_domain_cd_entry() only works on S1 domains
> attached to RIDs and refreshes all their CDs.
>
> Remove the forced clear of the CD during S1 domain attach,
> arm_smmu_write_cd_entry() will do this automatically if necessary.
>
> Tested-by: Nicolin Chen <nicolinc@nvidia.com>
> Tested-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
> Reviewed-by: Michael Shavit <mshavit@google.com>
> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
> ---
> .../iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c | 25 +++++++-
> drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 60 +++++++++++++------
> drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h | 9 +++
> 3 files changed, 76 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
> index 41b44baef15e80..d159f60480935e 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
> @@ -53,6 +53,29 @@ static void arm_smmu_update_ctx_desc_devices(struct arm_smmu_domain *smmu_domain
> spin_unlock_irqrestore(&smmu_domain->devices_lock, flags);
> }
>
> +static void
> +arm_smmu_update_s1_domain_cd_entry(struct arm_smmu_domain *smmu_domain)

nit: shouldn’t that be arm_smmu_update_sva_domain_cd_entry?
> +{
> + struct arm_smmu_master *master;
> + struct arm_smmu_cd target_cd;
> + unsigned long flags;
> +
> + spin_lock_irqsave(&smmu_domain->devices_lock, flags);
> + list_for_each_entry(master, &smmu_domain->devices, domain_head) {
> + struct arm_smmu_cd *cdptr;
> +
> + /* S1 domains only support RID attachment right now */
> + cdptr = arm_smmu_get_cd_ptr(master, IOMMU_NO_PASID);
> + if (WARN_ON(!cdptr))
> + continue;
> +
> + arm_smmu_make_s1_cd(&target_cd, master, smmu_domain);
> + arm_smmu_write_cd_entry(master, IOMMU_NO_PASID, cdptr,
> + &target_cd);

Case ARM_SMMU_DOMAIN_S1 has the some code:
arm_smmu_get_cd_pter => arm_smmu_make_s1_cd => arm_smmu_write_cd_entry
I’d prefer if that was abstracted with the SMMUv3 driver and it provides a higher
level API rather than exposing these low-level functions in the header file.
But no strong opinion.

> + }
> + spin_unlock_irqrestore(&smmu_domain->devices_lock, flags);
> +}
> +
> /*
> * Check if the CPU ASID is available on the SMMU side. If a private context
> * descriptor is using it, try to replace it.
> @@ -96,7 +119,7 @@ arm_smmu_share_asid(struct mm_struct *mm, u16 asid)
> * be some overlap between use of both ASIDs, until we invalidate the
> * TLB.
> */
> - arm_smmu_update_ctx_desc_devices(smmu_domain, IOMMU_NO_PASID, cd);
> + arm_smmu_update_s1_domain_cd_entry(smmu_domain);
>
> /* Invalidate TLB entries previously associated with that context */
> arm_smmu_tlb_inv_asid(smmu, asid);
> 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 3983de90c2fa01..d24fa13a52b4e0 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> @@ -1204,8 +1204,8 @@ static void arm_smmu_write_cd_l1_desc(__le64 *dst,
> WRITE_ONCE(*dst, cpu_to_le64(val));
> }
>
> -static struct arm_smmu_cd *arm_smmu_get_cd_ptr(struct arm_smmu_master *master,
> - u32 ssid)
> +struct arm_smmu_cd *arm_smmu_get_cd_ptr(struct arm_smmu_master *master,
> + u32 ssid)
> {
> __le64 *l1ptr;
> unsigned int idx;
> @@ -1268,9 +1268,9 @@ static const struct arm_smmu_entry_writer_ops arm_smmu_cd_writer_ops = {
> .v_bit = cpu_to_le64(CTXDESC_CD_0_V),
> };
>
> -static void arm_smmu_write_cd_entry(struct arm_smmu_master *master, int ssid,
> - struct arm_smmu_cd *cdptr,
> - const struct arm_smmu_cd *target)
> +void arm_smmu_write_cd_entry(struct arm_smmu_master *master, int ssid,
> + struct arm_smmu_cd *cdptr,
> + const struct arm_smmu_cd *target)
> {
> struct arm_smmu_cd_writer cd_writer = {
> .writer = {
> @@ -1283,6 +1283,32 @@ static void arm_smmu_write_cd_entry(struct arm_smmu_master *master, int ssid,
> arm_smmu_write_entry(&cd_writer.writer, cdptr->data, target->data);
> }
>
> +void arm_smmu_make_s1_cd(struct arm_smmu_cd *target,
> + struct arm_smmu_master *master,
> + struct arm_smmu_domain *smmu_domain)
> +{
> + struct arm_smmu_ctx_desc *cd = &smmu_domain->cd;
> +
> + memset(target, 0, sizeof(*target));
> +
> + target->data[0] = cpu_to_le64(
> + cd->tcr |
> +#ifdef __BIG_ENDIAN
> + CTXDESC_CD_0_ENDI |
> +#endif
> + CTXDESC_CD_0_V |
> + CTXDESC_CD_0_AA64 |
> + (master->stall_enabled ? CTXDESC_CD_0_S : 0) |
> + CTXDESC_CD_0_R |
> + CTXDESC_CD_0_A |
> + CTXDESC_CD_0_ASET |
> + FIELD_PREP(CTXDESC_CD_0_ASID, cd->asid)
> + );
> +
> + target->data[1] = cpu_to_le64(cd->ttbr & CTXDESC_CD_1_TTB0_MASK);
> + target->data[3] = cpu_to_le64(cd->mair);
> +}
> +

IMO, patches to handle CD = NULL and quiet CD should be introduced first so it is
easier to follow as now there is duplicate code in arm_smmu_write_ctx_desc() which
is dead and makes it a little harder to review, but if reordered,
arm_smmu_write_ctx_desc() can be removed in this patch so we can see how code moved.

Otherwise:
Reviewed-by: Mostafa Saleh <smostafa@google.com>

Thanks,
Mostafa
> static void arm_smmu_clean_cd_entry(struct arm_smmu_cd *target)
> {
> struct arm_smmu_cd used = {};
> @@ -2644,29 +2670,29 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
> spin_unlock_irqrestore(&smmu_domain->devices_lock, flags);
>
> switch (smmu_domain->stage) {
> - case ARM_SMMU_DOMAIN_S1:
> + case ARM_SMMU_DOMAIN_S1: {
> + struct arm_smmu_cd target_cd;
> + struct arm_smmu_cd *cdptr;
> +
> if (!master->cd_table.cdtab) {
> ret = arm_smmu_alloc_cd_tables(master);
> if (ret)
> goto out_list_del;
> - } else {
> - /*
> - * arm_smmu_write_ctx_desc() relies on the entry being
> - * invalid to work, clear any existing entry.
> - */
> - ret = arm_smmu_write_ctx_desc(master, IOMMU_NO_PASID,
> - NULL);
> - if (ret)
> - goto out_list_del;
> }
>
> - ret = arm_smmu_write_ctx_desc(master, IOMMU_NO_PASID, &smmu_domain->cd);
> - if (ret)
> + cdptr = arm_smmu_get_cd_ptr(master, IOMMU_NO_PASID);
> + if (!cdptr) {
> + ret = -ENOMEM;
> goto out_list_del;
> + }
>
> + arm_smmu_make_s1_cd(&target_cd, master, smmu_domain);
> + arm_smmu_write_cd_entry(master, IOMMU_NO_PASID, cdptr,
> + &target_cd);
> arm_smmu_make_cdtable_ste(&target, master);
> arm_smmu_install_ste_for_dev(master, &target);
> break;
> + }
> case ARM_SMMU_DOMAIN_S2:
> arm_smmu_make_s2_domain_ste(&target, master, smmu_domain);
> arm_smmu_install_ste_for_dev(master, &target);
> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
> index 4b767e0eeeb682..bb08f087ba39e4 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
> @@ -751,6 +751,15 @@ extern struct xarray arm_smmu_asid_xa;
> extern struct mutex arm_smmu_asid_lock;
> extern struct arm_smmu_ctx_desc quiet_cd;
>
> +struct arm_smmu_cd *arm_smmu_get_cd_ptr(struct arm_smmu_master *master,
> + u32 ssid);
> +void arm_smmu_make_s1_cd(struct arm_smmu_cd *target,
> + struct arm_smmu_master *master,
> + struct arm_smmu_domain *smmu_domain);
> +void arm_smmu_write_cd_entry(struct arm_smmu_master *master, int ssid,
> + struct arm_smmu_cd *cdptr,
> + const struct arm_smmu_cd *target);
> +
> int arm_smmu_write_ctx_desc(struct arm_smmu_master *smmu_master, int ssid,
> struct arm_smmu_ctx_desc *cd);
> void arm_smmu_tlb_inv_asid(struct arm_smmu_device *smmu, u16 asid);
> --
> 2.43.2