Re: [PATCH v7 9/9] iommu/vt-d: Add iotlb flush for nested domain

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On 2023/12/27 17:27, Duan, Zhenzhong wrote:


-----Original Message-----
From: Liu, Yi L <yi.l.liu@xxxxxxxxx>
Subject: [PATCH v7 9/9] iommu/vt-d: Add iotlb flush for nested domain

From: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>

This implements the .cache_invalidate_user() callback to support iotlb
flush for nested domain.

Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
Co-developed-by: Yi Liu <yi.l.liu@xxxxxxxxx>
Signed-off-by: Yi Liu <yi.l.liu@xxxxxxxxx>
---
drivers/iommu/intel/nested.c | 116
+++++++++++++++++++++++++++++++++++
1 file changed, 116 insertions(+)

diff --git a/drivers/iommu/intel/nested.c b/drivers/iommu/intel/nested.c
index b5a5563ab32c..c665e2647045 100644
--- a/drivers/iommu/intel/nested.c
+++ b/drivers/iommu/intel/nested.c
@@ -73,9 +73,125 @@ static void intel_nested_domain_free(struct
iommu_domain *domain)
	kfree(to_dmar_domain(domain));
}

+static void nested_flush_pasid_iotlb(struct intel_iommu *iommu,
+				     struct dmar_domain *domain, u64 addr,
+				     unsigned long npages, bool ih)
+{
+	u16 did = domain_id_iommu(domain, iommu);
+	unsigned long flags;
+
+	spin_lock_irqsave(&domain->lock, flags);
+	if (!list_empty(&domain->devices))
+		qi_flush_piotlb(iommu, did, IOMMU_NO_PASID, addr,
+				npages, ih, NULL);

Is it optimal to check if domain attached to iommu before trigger flush?
Or the check is redundant if intel_nested_flush_cache() is the only call site.

I think it is possible that userspace issue an invalidation on a hwpt which
does not have any device attached.. Though this is something stupid. So
checking if any device attached before flushing still makes sense.

Thanks
Zhenzhong

+	spin_unlock_irqrestore(&domain->lock, flags);
+}
+
+static void nested_flush_dev_iotlb(struct dmar_domain *domain, u64 addr,
+				   unsigned mask, u32 *fault)
+{
+	struct device_domain_info *info;
+	unsigned long flags;
+	u16 sid, qdep;
+
+	spin_lock_irqsave(&domain->lock, flags);
+	list_for_each_entry(info, &domain->devices, link) {
+		if (!info->ats_enabled)
+			continue;
+		sid = info->bus << 8 | info->devfn;
+		qdep = info->ats_qdep;
+		qi_flush_dev_iotlb(info->iommu, sid, info->pfsid,
+				   qdep, addr, mask, fault);
+		quirk_extra_dev_tlb_flush(info, addr, mask,
+					  IOMMU_NO_PASID, qdep);
+	}
+	spin_unlock_irqrestore(&domain->lock, flags);
+}
+
+static void intel_nested_flush_cache(struct dmar_domain *domain, u64
addr,
+				     unsigned long npages, u32 *error)
+{
+	struct iommu_domain_info *info;
+	unsigned long i;
+	unsigned mask;
+	u32 fault = 0;
+
+	if (npages == U64_MAX)
+		mask = 64 - VTD_PAGE_SHIFT;
+	else
+		mask = ilog2(__roundup_pow_of_two(npages));
+
+	xa_for_each(&domain->iommu_array, i, info) {
+		nested_flush_pasid_iotlb(info->iommu, domain, addr,
npages, 0);
+
+		if (domain->has_iotlb_device)
+			continue;
+
+		nested_flush_dev_iotlb(domain, addr, mask, &fault);
+		if (fault & (DMA_FSTS_ITE | DMA_FSTS_ICE))
+			break;
+	}
+
+	if (fault & DMA_FSTS_ICE)
+		*error |= IOMMU_HWPT_INVALIDATE_VTD_S1_ICE;
+	if (fault & DMA_FSTS_ITE)
+		*error |= IOMMU_HWPT_INVALIDATE_VTD_S1_ITE;
+}
+
+static int intel_nested_cache_invalidate_user(struct iommu_domain
*domain,
+					      struct iommu_user_data_array
*array)
+{
+	struct dmar_domain *dmar_domain = to_dmar_domain(domain);
+	struct iommu_hwpt_vtd_s1_invalidate inv_entry;
+	u32 processed = 0;
+	int ret = 0;
+	u32 index;
+
+	if (array->type != IOMMU_HWPT_INVALIDATE_DATA_VTD_S1) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	for (index = 0; index < array->entry_num; index++) {
+		ret = iommu_copy_struct_from_user_array(&inv_entry,
array,
+
	IOMMU_HWPT_INVALIDATE_DATA_VTD_S1,
+							index, inv_error);
+		if (ret)
+			break;
+
+		if (inv_entry.flags & ~IOMMU_VTD_INV_FLAGS_LEAF) {
+			ret = -EOPNOTSUPP;
+			break;
+		}
+
+		if (!IS_ALIGNED(inv_entry.addr, VTD_PAGE_SIZE) ||
+		    ((inv_entry.npages == U64_MAX) && inv_entry.addr)) {
+			ret = -EINVAL;
+			break;
+		}
+
+		inv_entry.inv_error = 0;
+		intel_nested_flush_cache(dmar_domain, inv_entry.addr,
+					 inv_entry.npages,
&inv_entry.inv_error);
+
+		ret = iommu_respond_struct_to_user_array(array, index,
+							 (void *)&inv_entry,
+							 sizeof(inv_entry));
+		if (ret)
+			break;
+
+		processed++;
+	}
+
+out:
+	array->entry_num = processed;
+	return ret;
+}
+
static const struct iommu_domain_ops intel_nested_domain_ops = {
	.attach_dev		= intel_nested_attach_dev,
	.free			= intel_nested_domain_free,
+	.cache_invalidate_user	= intel_nested_cache_invalidate_user,
};

struct iommu_domain *intel_nested_domain_alloc(struct iommu_domain
*parent,
--
2.34.1


--
Regards,
Yi Liu




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