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

Lu Baolu
2020-03-29T08:03:43Z

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.

>
>> + *
>> + * @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.

>
>> +
>> + 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