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

Tian, Kevin
2020-03-31T03:36:39Z

> From: Jacob Pan <jacob.jun.pan@linux.intel.com>
> Sent: Tuesday, March 31, 2020 2:22 AM
>
> On Sun, 29 Mar 2020 16:03:36 +0800
> Lu Baolu <baolu.lu@linux.intel.com> wrote:
>
> > On 2020/3/27 20:21, Tian, Kevin wrote:
> > >> From: Jacob Pan <jacob.jun.pan@linux.intel.com>
> > >> 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 😊
> >
> > Updated.
> >
> > >
> > >> 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@linux.intel.com>
> > >> Signed-off-by: Liu, Yi L <yi.l.liu@linux.intel.com>
> > >> ---
> > >> 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?
> >
> > Jacob, does it work for you if I add below check?
> >
> > if (ecap_mts(iommu->ecap) && !dev_is_pci(dev))
> >
> > Or, we need to remove this comment line?
> >
> > >
> > >> + */
> > >> + 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.
> >
> > Agreed.
> >
> Yes, that is why I chose the word "could be" :), but mention both cases
> are good.

"could be" is fine. I read too fast.

>
> > >
> > >> + *
> > >> + * @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...
> >
> > Agreed. Will do this in a followup patch.
> >
> > >
> > >> +
> > >> + /*
> > >> + * 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.
> >
> > The pasid entry change should always be protected by iommu->lock.
> >
> Agreed.

yes, I realized it after completing the review of whole series. 😊

>
> > >
> > >> +
> > >> + 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
> > >
> >
> > Best regards,
> > baolu
>
> [Jacob Pan]