Re: [PATCH v2 13/19] iommu/vt-d: Add nested translation support

Auger Eric
2019-04-26T15:42:15Z

Hi Jacob,

On 4/24/19 1:31 AM, Jacob Pan wrote:
> Nested translation mode is supported in VT-d 3.0 Spec.CH 3.8.
> With PASID granular translation type set to 0x11b, translation
> result from the first level(FL) also subject to a second level(SL)
> page table translation. This mode is used for SVA virtualization,
> where FL performs guest virtual to guest physical translation and
> SL performs guest physical to host physical translation.

The title of the patch sounds a bit misleading to me as this patch
"just" adds a helper to set the PASID table entry in nested mode. There
is no caller yet.
>
> Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
> Signed-off-by: Liu, Yi L <yi.l.liu@linux.intel.com>
> ---
> drivers/iommu/intel-pasid.c | 101 ++++++++++++++++++++++++++++++++++++++++++++
> drivers/iommu/intel-pasid.h | 11 +++++
> 2 files changed, 112 insertions(+)
>
> diff --git a/drivers/iommu/intel-pasid.c b/drivers/iommu/intel-pasid.c
> index d339e8f..04127cf 100644
> --- a/drivers/iommu/intel-pasid.c
> +++ b/drivers/iommu/intel-pasid.c
> @@ -688,3 +688,104 @@ int intel_pasid_setup_pass_through(struct intel_iommu *iommu,
>
> return 0;
> }
> +
> +/**
> + * intel_pasid_setup_nested() - Set up PASID entry for nested translation
> + * which is used for vSVA. The first level page tables are used for
> + * GVA-GPA translation in the guest, second level page tables are used
> + * for GPA to HPA translation.
> + *
> + * @iommu: Iommu which the device belong to
> + * @dev: Device to be set up for translation
> + * @pgd: First level PGD, treated as GPA
nit: @gpgd

spec naming could be used as well: FLPTPTR: First Level Page
Translation Pointer
> + * @pasid: PASID to be programmed in the device PASID table
> + * @flags: Additional info such as supervisor PASID
> + * @domain: Domain info for setting up second level page tables
> + * @addr_width: Address width of the first level (guest)
> + */
> +int intel_pasid_setup_nested(struct intel_iommu *iommu,
> + struct device *dev, pgd_t *gpgd,
> + int pasid, int flags,
> + struct dmar_domain *domain,
> + int addr_width)
> +{
> + struct pasid_entry *pte;
> + struct dma_pte *pgd;
> + u64 pgd_val;
> + int agaw;
> + u16 did;
> +
> + if (!ecap_nest(iommu->ecap)) {
> + pr_err("No nested translation support on %s\n",
> + iommu->name);
IOMMU: %s: ;-)
> + return -EINVAL;
> + }
> +
> + pte = intel_pasid_get_entry(dev, pasid);
> + if (WARN_ON(!pte))
> + return -EINVAL;
> +
> + pasid_clear_entry(pte);
> +
> + /* Sanity checking performed by caller to make sure address
> + * width matching in two dimensions:
> + * 1. CPU vs. IOMMU
> + * 2. Guest vs. Host.
> + */
> + switch (addr_width) {
> + case 57:
> + pasid_set_flpm(pte, 1);
> + break;
> + case 48:
> + pasid_set_flpm(pte, 0);
> + break;
> + default:
> + dev_err(dev, "Invalid paging mode %d\n", addr_width);
> + return -EINVAL;
> + }
> +
> + /* Setup the first level page table pointer in GPA */
> + pasid_set_flptr(pte, (u64)gpgd);
> + if (flags & PASID_FLAG_SUPERVISOR_MODE) {
> + if (!ecap_srs(iommu->ecap)) {
> + pr_err("No supervisor request support on %s\n",
> + iommu->name);
> + return -EINVAL;
> + }
> + pasid_set_sre(pte);
> + }
> +
> + /* Setup the second level based on the given domain */
> + pgd = domain->pgd;
> +
> + for (agaw = domain->agaw; agaw != iommu->agaw; agaw--) {
> + pgd = phys_to_virt(dma_pte_addr(pgd));
> + if (!dma_pte_present(pgd)) {
> + dev_err(dev, "Invalid domain page table\n");
> + return -EINVAL;
> + }
> + }
> + pgd_val = virt_to_phys(pgd);
> + pasid_set_slptr(pte, pgd_val);
> + pasid_set_fault_enable(pte);
> +
> + did = domain->iommu_did[iommu->seq_id];
> + pasid_set_domain_id(pte, did);
> +
> + pasid_set_address_width(pte, agaw);
> + pasid_set_page_snoop(pte, !!ecap_smpwc(iommu->ecap));
> +
> + pasid_set_translation_type(pte, PASID_ENTRY_PGTT_NESTED);
> + pasid_set_present(pte);
> +
> + if (!ecap_coherent(iommu->ecap))
> + clflush_cache_range(pte, sizeof(*pte));
> +
> + if (cap_caching_mode(iommu->cap)) {
> + pasid_cache_invalidation_with_pasid(iommu, did, pasid);
> + iotlb_invalidation_with_pasid(iommu, did, pasid);
> + } else
> + iommu_flush_write_buffer(iommu);
a bunch of that code is duplicated from
intel_pasid_setup_second_level(). I wonder if you could devise a common
helper function?

Thanks

Eric
> +
> + return 0;
> +}
> diff --git a/drivers/iommu/intel-pasid.h b/drivers/iommu/intel-pasid.h
> index 0999dfe..c4fc1af 100644
> --- a/drivers/iommu/intel-pasid.h
> +++ b/drivers/iommu/intel-pasid.h
> @@ -42,6 +42,7 @@
> * to vmalloc or even module mappings.
> */
> #define PASID_FLAG_SUPERVISOR_MODE BIT(0)
> +#define PASID_FLAG_NESTED BIT(1)
>
> struct pasid_dir_entry {
> u64 val;
> @@ -51,6 +52,11 @@ struct pasid_entry {
> u64 val[8];
> };
>
> +#define PASID_ENTRY_PGTT_FL_ONLY (1)
> +#define PASID_ENTRY_PGTT_SL_ONLY (2)
> +#define PASID_ENTRY_PGTT_NESTED (3)
> +#define PASID_ENTRY_PGTT_PT (4)
> +
> /* The representative of a PASID table */
> struct pasid_table {
> void *table; /* pasid table pointer */
> @@ -77,6 +83,11 @@ int intel_pasid_setup_second_level(struct intel_iommu *iommu,
> int intel_pasid_setup_pass_through(struct intel_iommu *iommu,
> struct dmar_domain *domain,
> struct device *dev, int pasid);
> +int intel_pasid_setup_nested(struct intel_iommu *iommu,
> + struct device *dev, pgd_t *pgd,
> + int pasid, int flags,
> + struct dmar_domain *domain,
> + int addr_width);
> void intel_pasid_tear_down_entry(struct intel_iommu *iommu,
> struct device *dev, int pasid);
> int vcmd_alloc_pasid(struct intel_iommu *iommu, unsigned int *pasid);
>