RE: [PATCH V10 05/11] iommu/vt-d: Add nested translation helper function

From: Tian, Kevin
Date: Fri Mar 27 2020 - 08:21:20 EST

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> From: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
> Sent: Saturday, March 21, 2020 7:28 AM
>
> Nested translation mode is supported in VT-d 3.0 Spec.CH 3.8.

now the spec is already at rev3.1 ð

> 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.
>
> This patch adds a helper function for setting up nested translation
> where second level comes from a domain and first level comes from
> a guest PGD.
>
> Signed-off-by: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
> Signed-off-by: Liu, Yi L <yi.l.liu@xxxxxxxxxxxxxxx>
> ---
> drivers/iommu/intel-pasid.c | 240
> +++++++++++++++++++++++++++++++++++++++++++-
> drivers/iommu/intel-pasid.h | 12 +++
> include/linux/intel-iommu.h | 3 +
> 3 files changed, 252 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/iommu/intel-pasid.c b/drivers/iommu/intel-pasid.c
> index 9bdb7ee228b6..10c7856afc6b 100644
> --- a/drivers/iommu/intel-pasid.c
> +++ b/drivers/iommu/intel-pasid.c
> @@ -359,6 +359,76 @@ 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 << 32);
> +}
> +
> +/*
> + * 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 << 25);
> +}
> +
> +/*
> + * 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 << 26);
> +}
> +
> +/*
> + * 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 << 7);
> +}
> +
> +/*
> + * 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 << 31);
> +}
> +
> +/*
> + * 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 << 30);
> +}
> +
> static void
> pasid_cache_invalidation_with_pasid(struct intel_iommu *iommu,
> u16 did, int pasid)
> @@ -492,7 +562,7 @@ int intel_pasid_setup_first_level(struct intel_iommu
> *iommu,
> pasid_set_page_snoop(pte, !!ecap_smpwc(iommu->ecap));
>
> /* Setup Present and PASID Granular Transfer Type: */
> - pasid_set_translation_type(pte, 1);
> + pasid_set_translation_type(pte, PASID_ENTRY_PGTT_FL_ONLY);
> pasid_set_present(pte);
> pasid_flush_caches(iommu, pte, pasid, did);
>
> @@ -564,7 +634,7 @@ int intel_pasid_setup_second_level(struct
> intel_iommu *iommu,
> pasid_set_domain_id(pte, did);
> pasid_set_slptr(pte, pgd_val);
> pasid_set_address_width(pte, agaw);
> - pasid_set_translation_type(pte, 2);
> + pasid_set_translation_type(pte, PASID_ENTRY_PGTT_SL_ONLY);
> pasid_set_fault_enable(pte);
> pasid_set_page_snoop(pte, !!ecap_smpwc(iommu->ecap));
>
> @@ -598,7 +668,7 @@ int intel_pasid_setup_pass_through(struct
> intel_iommu *iommu,
> pasid_clear_entry(pte);
> pasid_set_domain_id(pte, did);
> pasid_set_address_width(pte, iommu->agaw);
> - pasid_set_translation_type(pte, 4);
> + pasid_set_translation_type(pte, PASID_ENTRY_PGTT_PT);
> pasid_set_fault_enable(pte);
> pasid_set_page_snoop(pte, !!ecap_smpwc(iommu->ecap));
>
> @@ -612,3 +682,167 @@ 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) {
> + if (!ecap_eafs(iommu->ecap)) {
> + pr_err("No extended access flag support on %s\n",
> + iommu->name);
> + return -EINVAL;
> + }
> + pasid_set_eafe(pte);
> + }
> +
> + /*
> + * 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.

when you say that PCI devices are not included, is it simple for information
or should we impose some check to make sure below path not applied to
them?

> + */
> + if (ecap_mts(iommu->ecap)) {
> + if (pasid_data->flags & IOMMU_SVA_VTD_GPASID_EMTE) {
> + pasid_set_emte(pte);
> + pasid_set_emt(pte, pasid_data->emt);
> + }
> + 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);
> + } else if (pasid_data->flags & IOMMU_SVA_VTD_GPASID_MTS_MASK)
> {
> + pr_err("No memory type support for bind guest PASID
> on %s\n",
> + iommu->name);
> + return -EINVAL;
> + }
> +
> + return 0;
> +
> +}
> +
> +/**
> + * intel_pasid_setup_nested() - Set up PASID entry for nested translation.
> + * This could be used for guest shared virtual address. In this case, the
> + * first level page tables are used for GVA-GPA translation in the guest,
> + * second level page tables are used for GPA-HPA translation.

GVA->GPA is just one example. It could be gIOVA->GPA too. Here the
point is that the first level is the translation table managed by the 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;
> + int ret = 0;
> + 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;

should we have intel_pasid_get_entry to return error which is then carried
here? Looking at that function there could be error conditions both being
invalid parameter and no memory...

> +
> + /*
> + * Caller must ensure PASID entry is not in use, i.e. not bind the
> + * same PASID to the same device twice.
> + */
> + if (pasid_pte_is_present(pte))
> + return -EBUSY;

is any lock held outside of this function? curious whether any race
condition may happen in between.

> +
> + 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 ADDR_WIDTH_5LEVEL:
> + if (cpu_feature_enabled(X86_FEATURE_LA57) &&
> + cap_5lp_support(iommu->cap)) {
> + pasid_set_flpm(pte, 1);

define a macro for 4lvl and 5lvl

> + } else {
> + dev_err(dev, "5-level paging not supported\n");
> + return -EINVAL;
> + }
> + break;
> + case ADDR_WIDTH_4LEVEL:
> + pasid_set_flpm(pte, 0);
> + break;
> + default:
> + dev_err(dev, "Invalid guest address width %d\n",
> addr_width);
> + return -EINVAL;
> + }
> +
> + /* First level PGD is in GPA, must be supported by the second level */
> + if ((u64)gpgd > domain->max_addr) {
> + dev_err(dev, "Guest PGD %llx not supported, max %llx\n",
> + (u64)gpgd, domain->max_addr);
> + return -EINVAL;
> + }
> + pasid_set_flptr(pte, (u64)gpgd);
> +
> + ret = intel_pasid_setup_bind_data(iommu, pte, pasid_data);
> + if (ret) {
> + dev_err(dev, "Guest PASID bind data not supported\n");
> + return ret;
> + }
> +
> + /* Setup the second level based on the given domain */
> + pgd = domain->pgd;
> +
> + agaw = iommu_skip_agaw(domain, iommu, &pgd);
> + if (agaw < 0) {
> + 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);
> + pasid_flush_caches(iommu, pte, pasid, did);
> +
> + return ret;
> +}
> diff --git a/drivers/iommu/intel-pasid.h b/drivers/iommu/intel-pasid.h
> index 92de6df24ccb..698015ee3f04 100644
> --- a/drivers/iommu/intel-pasid.h
> +++ b/drivers/iommu/intel-pasid.h
> @@ -36,6 +36,7 @@
> * to vmalloc or even module mappings.
> */
> #define PASID_FLAG_SUPERVISOR_MODE BIT(0)
> +#define PASID_FLAG_NESTED BIT(1)
>
> /*
> * The PASID_FLAG_FL5LP flag Indicates using 5-level paging for first-
> @@ -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 */
> @@ -99,6 +105,12 @@ 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);
>
> diff --git a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h
> index ed7171d2ae1f..eda1d6687144 100644
> --- a/include/linux/intel-iommu.h
> +++ b/include/linux/intel-iommu.h
> @@ -42,6 +42,9 @@
> #define DMA_FL_PTE_PRESENT BIT_ULL(0)
> #define DMA_FL_PTE_XD BIT_ULL(63)
>
> +#define ADDR_WIDTH_5LEVEL (57)
> +#define ADDR_WIDTH_4LEVEL (48)
> +
> #define CONTEXT_TT_MULTI_LEVEL 0
> #define CONTEXT_TT_DEV_IOTLB 1
> #define CONTEXT_TT_PASS_THROUGH 2
> --
> 2.7.4

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