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Subject: Re: [PATCH V9 03/10] iommu/vt-d: Add nested translation helper
 function
To:     Jacob Pan <jacob.jun.pan@linux.intel.com>,
        iommu@lists.linux-foundation.org,
        LKML <linux-kernel@vger.kernel.org>,
        Lu Baolu <baolu.lu@linux.intel.com>,
        Joerg Roedel <joro@8bytes.org>,
        David Woodhouse <dwmw2@infradead.org>
Cc:     Yi Liu <yi.l.liu@intel.com>, "Tian, Kevin" <kevin.tian@intel.com>,
        Raj Ashok <ashok.raj@intel.com>,
        Alex Williamson <alex.williamson@redhat.com>,
        Christoph Hellwig <hch@infradead.org>,
        Jean-Philippe Brucker <jean-philippe@linaro.com>,
        Jonathan Cameron <jic23@kernel.org>,
        Yi L <yi.l.liu@linux.intel.com>
References: <1580277713-66934-1-git-send-email-jacob.jun.pan@linux.intel.com>
 <1580277713-66934-4-git-send-email-jacob.jun.pan@linux.intel.com>
From:   Auger Eric <eric.auger@redhat.com>
Message-ID: <7d127a3d-fddf-e180-3d5a-3cd6c330fba5@redhat.com>
Date:   Wed, 12 Feb 2020 13:43:17 +0100
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Hi Jacob,
On 1/29/20 7:01 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.
You may also describe what the patch brings. The above text does not.
> 
> 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 | 225 ++++++++++++++++++++++++++++++++++++++++++++
>  drivers/iommu/intel-pasid.h |  12 +++
>  include/linux/intel-iommu.h |   3 +
>  3 files changed, 240 insertions(+)
> 
> diff --git a/drivers/iommu/intel-pasid.c b/drivers/iommu/intel-pasid.c
> index 22b30f10b396..bd067af4d20b 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)
pat is 32b
> +{
> +	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);
BIT_ULL() here and below?
My preference would have been to a have a helper converting absolute
field boundaries (as the spec, Fig 9-36 describes those with absolute
values) into the right val and offset. I think it would be less error
prone globally.
> +}
> +
> +/*
> + * 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)
> @@ -596,3 +666,158 @@ 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.
s/of  /of /
> +	 */
> +	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.
> +	 */
> +	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);
why isn't the pat struct member also guarded by a flag. If I understand
correctly it should not be set of MTS is not supported.
> +	} else if (pasid_data->flags & IOMMU_SVA_VTD_GPASID_EMT_MASK) {
> +		pr_warn("No memory type support for bind guest PASID on %s\n",
> +			iommu->name);
why not pr_err() here as well?
> +		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.
> + *
> + * @iommu:      Iommu which the device belong to
s/Iommu/iommu or IOMMU, belongs
> + * @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);
in intel_pasid_get_entry() there may be one WARN_ON hitting in some
conditions. But I see other callers of intel_pasid_get_entry also have
the WARN_ON.
> +	if (WARN_ON(!pte))
> +		return -EINVAL;
> +
> +	/*
> +	 * 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;
> +
> +	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:
> +		pasid_set_flpm(pte, 1);
don't you need to check whether 5-level paging mode is supported (5LP)
This data comes from userspace
> +		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;
> +	}
> +
> +	pasid_set_flptr(pte, (u64)gpgd);
don't you need to do some checks on the gpgd versus the max addr_width
supported by the HW?
> +
> +	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;
> +
> +	for (agaw = domain->agaw; agaw != iommu->agaw; agaw--) {
> +		pgd = phys_to_virt(dma_pte_addr(pgd));
> +		if (!dma_pte_present(pgd)) {
> +			pasid_clear_entry(pte);
here you clear the PTE entry while above, on the other error cases you
don't. Any reason?
> +			dev_err(dev, "Invalid domain page table\n");
> +			return -EINVAL;
> +		}
> +	}
Maybe you could introduce an helper as the above code is duplicated in
intel_pasid_setup_second_level
> +	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)
May use the above in the relevant places. Otherwise they may not be used.
> +#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 27c6bbb0a333..c8abf051b2d5 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
> 

Thanks

Eric