RE: [PATCH v7 07/11] iommu/vt-d: Add nested translation helper function

Tian, Kevin
2019-10-25T07:04:34Z

> From: Jacob Pan [mailto:jacob.jun.pan@linux.intel.com]
> Sent: Friday, October 25, 2019 3:55 AM
>
> 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.

I think we really differentiate what is the common logic for
first-level usages (GVA, GIOVA, etc.) in scalable mode, and
what is specific to SVA. I have the feeling that SVA is over-used
to cause confusing interpretation.

>
> 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 | 207
> ++++++++++++++++++++++++++++++++++++++++++++
> drivers/iommu/intel-pasid.h | 12 +++
> 2 files changed, 219 insertions(+)
>
> diff --git a/drivers/iommu/intel-pasid.c b/drivers/iommu/intel-pasid.c
> index ffbd416ed3b8..f846a907cfcf 100644
> --- a/drivers/iommu/intel-pasid.c
> +++ b/drivers/iommu/intel-pasid.c
> @@ -415,6 +415,76 @@ pasid_set_flpm(struct pasid_entry *pe, u64 value)
> pasid_set_bits(&pe->val[2], GENMASK_ULL(3, 2), value << 2);
> }
>
> +/*
> + * Setup the Extended Memory Type(EMT) field (Bits 91-93)
> + * of a scalable mode PASID entry.
> + */
> +static inline void
> +pasid_set_emt(struct pasid_entry *pe, u64 value)
> +{
> + pasid_set_bits(&pe->val[1], GENMASK_ULL(29, 27), value << 27);
> +}
> +
> +/*
> + * Setup the Page Attribute Table (PAT) field (Bits 96-127)
> + * of a scalable mode PASID entry.
> + */
> +static inline void
> +pasid_set_pat(struct pasid_entry *pe, u64 value)
> +{
> + pasid_set_bits(&pe->val[1], GENMASK_ULL(63, 32), value << 27);
> +}
> +
> +/*
> + * Setup the Cache Disable (CD) field (Bit 89)
> + * of a scalable mode PASID entry.
> + */
> +static inline void
> +pasid_set_cd(struct pasid_entry *pe)
> +{
> + pasid_set_bits(&pe->val[1], 1 << 25, 1);
> +}
> +
> +/*
> + * Setup the Extended Memory Type Enable (EMTE) field (Bit 90)
> + * of a scalable mode PASID entry.
> + */
> +static inline void
> +pasid_set_emte(struct pasid_entry *pe)
> +{
> + pasid_set_bits(&pe->val[1], 1 << 26, 1);
> +}
> +
> +/*
> + * Setup the Extended Access Flag Enable (EAFE) field (Bit 135)
> + * of a scalable mode PASID entry.
> + */
> +static inline void
> +pasid_set_eafe(struct pasid_entry *pe)
> +{
> + pasid_set_bits(&pe->val[2], 1 << 7, 1);
> +}
> +
> +/*
> + * Setup the Page-level Cache Disable (PCD) field (Bit 95)
> + * of a scalable mode PASID entry.
> + */
> +static inline void
> +pasid_set_pcd(struct pasid_entry *pe)
> +{
> + pasid_set_bits(&pe->val[1], 1 << 31, 1);
> +}
> +
> +/*
> + * Setup the Page-level Write-Through (PWT)) field (Bit 94)
> + * of a scalable mode PASID entry.
> + */
> +static inline void
> +pasid_set_pwt(struct pasid_entry *pe)
> +{
> + pasid_set_bits(&pe->val[1], 1 << 30, 1);
> +}
> +
> static void
> pasid_cache_invalidation_with_pasid(struct intel_iommu *iommu,
> u16 did, int pasid)
> @@ -647,3 +717,140 @@ int intel_pasid_setup_pass_through(struct
> intel_iommu *iommu,
>
> return 0;
> }
> +
> +static int intel_pasid_setup_bind_data(struct intel_iommu *iommu,
> + struct pasid_entry *pte,
> + struct iommu_gpasid_bind_data_vtd
> *pasid_data)
> +{
> + /*
> + * Not all guest PASID table entry fields are passed down during
> bind,
> + * here we only set up the ones that are dependent on guest
> settings.
> + * Execution related bits such as NXE, SMEP are not meaningful to
> IOMMU,
> + * therefore not set. Other fields, such as snoop related, are set
> based
> + * on host needs regardless of guest settings.
> + */
> + if (pasid_data->flags & IOMMU_SVA_VTD_GPASID_SRE) {
> + if (!ecap_srs(iommu->ecap)) {
> + pr_err("No supervisor request support on %s\n",
> + iommu->name);
> + return -EINVAL;
> + }
> + pasid_set_sre(pte);
> + }
> +
> + if ((pasid_data->flags & IOMMU_SVA_VTD_GPASID_EAFE) &&
> ecap_eafs(iommu->ecap))
> + pasid_set_eafe(pte);
> +
> + if (pasid_data->flags & IOMMU_SVA_VTD_GPASID_EMTE) {
> + pasid_set_emte(pte);
> + pasid_set_emt(pte, pasid_data->emt);
> + }

above conditional checks are not consistent. The 1st check may
return error but latter two don't. Can you confirm whether it's
desired way?

> +
> + /*
> + * Memory type is only applicable to devices inside processor
> coherent
> + * domain. PCIe devices are not included. We can skip the rest of
> the
> + * flags if IOMMU does not support MTS.
> + */
> + if (!ecap_mts(iommu->ecap)) {
> + pr_info("%s does not support memory type bind guest
> PASID\n",
> + iommu->name);
> + return 0;

why not -EINVAL?

> + }
> +
> + if (pasid_data->flags & IOMMU_SVA_VTD_GPASID_PCD)
> + pasid_set_pcd(pte);
> + if (pasid_data->flags & IOMMU_SVA_VTD_GPASID_PWT)
> + pasid_set_pwt(pte);
> + if (pasid_data->flags & IOMMU_SVA_VTD_GPASID_CD)
> + pasid_set_cd(pte);
> + pasid_set_pat(pte, pasid_data->pat);
> +
> + 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.

It's too restricting on how 1st level is used by guest.

> + *
> + * @iommu: Iommu which the device belong to
> + * @dev: Device to be set up for translation
> + * @gpgd: FLPTPTR: First Level Page translation pointer in GPA
> + * @pasid: PASID to be programmed in the device PASID table
> + * @pasid_data: Additional PASID info from the guest bind request
> + * @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, struct iommu_gpasid_bind_data_vtd
> *pasid_data,
> + 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("IOMMU: %s: No nested translation support\n",
> + iommu->name);
> + 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:

AW_5LEVEL

> + pasid_set_flpm(pte, 1);
> + break;
> + case 48:

AW_4LEVEL

> + pasid_set_flpm(pte, 0);
> + break;
> + default:
> + dev_err(dev, "Invalid paging mode %d\n", addr_width);
> + return -EINVAL;
> + }
> +
> + pasid_set_flptr(pte, (u64)gpgd);
> +
> + intel_pasid_setup_bind_data(iommu, pte, pasid_data);
> +
> + /* 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");

pasid_clear_entry?

> + 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);
> + pasid_flush_caches(iommu, pte, pasid, did);
> +
> + return 0;
> +}
> diff --git a/drivers/iommu/intel-pasid.h b/drivers/iommu/intel-pasid.h
> index e413e884e685..09c85db73b77 100644
> --- a/drivers/iommu/intel-pasid.h
> +++ b/drivers/iommu/intel-pasid.h
> @@ -46,6 +46,7 @@
> * 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;
> @@ -55,6 +56,11 @@ 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 */
> @@ -103,6 +109,12 @@ 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,
> + struct iommu_gpasid_bind_data_vtd *pasid_data,
> + 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);
> --
> 2.7.4