From 93de2a6a4b91b72607136dd656edf03fb399d27f Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Wed, 23 Sep 2026 09:37:21 -0700 Subject: KVM: SEV: Do cache maintenance on the source VM during intra-host migration Manually perform cache maintenance on the source VM during intra-host migration to ensure no stale data is left in CPU caches after the VM is destroyed. Because the source VM is "converted" to a non-SEV VM, KVM's memory reclaim flows won't trigger cache maintenance, e.g. when all guest memory is reclaimed in response to detaching from the mmu_notifier. Note, relying on the destination VM to do cache maintenance isn't an option as KVM doesn't require identical guest memory configurations, i.e. the source VM may have access to memory that the destination VM does not. Enforcing equivalent memory configurations is infeasible, as it would require a *deep* comparison of memslots, e.g. to verify that not only are the memslot identical, but what the memslots point at is also identical. Fixes: b56639318bb2 ("KVM: SEV: Add support for SEV intra host migration") Cc: stable@vger.kernel.org Reported-by: Stefan Teodorescu Signed-off-by: Sean Christopherson Message-ID: <20260923163721.1584779-3-seanjc@google.com> Signed-off-by: Paolo Bonzini --- drivers/iommu/intel/cache.c | 520 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 520 insertions(+) create mode 100644 drivers/iommu/intel/cache.c (limited to 'drivers/iommu/intel/cache.c') diff --git a/drivers/iommu/intel/cache.c b/drivers/iommu/intel/cache.c new file mode 100644 index 000000000..26a758b0f --- /dev/null +++ b/drivers/iommu/intel/cache.c @@ -0,0 +1,520 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * cache.c - Intel VT-d cache invalidation + * + * Copyright (C) 2024 Intel Corporation + * + * Author: Lu Baolu + */ + +#define pr_fmt(fmt) "DMAR: " fmt + +#include +#include +#include +#include +#include + +#include "iommu.h" +#include "pasid.h" +#include "trace.h" + +/* Check if an existing cache tag can be reused for a new association. */ +static bool cache_tage_match(struct cache_tag *tag, u16 domain_id, + struct intel_iommu *iommu, struct device *dev, + ioasid_t pasid, enum cache_tag_type type) +{ + if (tag->type != type) + return false; + + if (tag->domain_id != domain_id || tag->pasid != pasid) + return false; + + if (type == CACHE_TAG_IOTLB || type == CACHE_TAG_NESTING_IOTLB) + return tag->iommu == iommu; + + if (type == CACHE_TAG_DEVTLB || type == CACHE_TAG_NESTING_DEVTLB) + return tag->dev == dev; + + return false; +} + +/* Assign a cache tag with specified type to domain. */ +int cache_tag_assign(struct dmar_domain *domain, u16 did, struct device *dev, + ioasid_t pasid, enum cache_tag_type type) +{ + struct device_domain_info *info = dev_iommu_priv_get(dev); + struct intel_iommu *iommu = info->iommu; + struct cache_tag *tag, *temp; + struct list_head *prev; + unsigned long flags; + + tag = kzalloc_obj(*tag); + if (!tag) + return -ENOMEM; + + tag->type = type; + tag->iommu = iommu; + tag->domain_id = did; + tag->pasid = pasid; + tag->users = 1; + + if (type == CACHE_TAG_DEVTLB || type == CACHE_TAG_NESTING_DEVTLB) + tag->dev = dev; + else + tag->dev = iommu->iommu.dev; + + spin_lock_irqsave(&domain->cache_lock, flags); + prev = &domain->cache_tags; + list_for_each_entry(temp, &domain->cache_tags, node) { + if (cache_tage_match(temp, did, iommu, dev, pasid, type)) { + temp->users++; + spin_unlock_irqrestore(&domain->cache_lock, flags); + kfree(tag); + trace_cache_tag_assign(temp); + return 0; + } + if (temp->iommu == iommu) + prev = &temp->node; + } + /* + * Link cache tags of same iommu unit together, so corresponding + * flush ops can be batched for iommu unit. + */ + list_add(&tag->node, prev); + + spin_unlock_irqrestore(&domain->cache_lock, flags); + trace_cache_tag_assign(tag); + + return 0; +} + +/* Unassign a cache tag with specified type from domain. */ +static void cache_tag_unassign(struct dmar_domain *domain, u16 did, + struct device *dev, ioasid_t pasid, + enum cache_tag_type type) +{ + struct device_domain_info *info = dev_iommu_priv_get(dev); + struct intel_iommu *iommu = info->iommu; + struct cache_tag *tag; + unsigned long flags; + + spin_lock_irqsave(&domain->cache_lock, flags); + list_for_each_entry(tag, &domain->cache_tags, node) { + if (cache_tage_match(tag, did, iommu, dev, pasid, type)) { + trace_cache_tag_unassign(tag); + if (--tag->users == 0) { + list_del(&tag->node); + kfree(tag); + } + break; + } + } + spin_unlock_irqrestore(&domain->cache_lock, flags); +} + +/* domain->qi_batch will be freed in iommu_free_domain() path. */ +static int domain_qi_batch_alloc(struct dmar_domain *domain) +{ + unsigned long flags; + int ret = 0; + + spin_lock_irqsave(&domain->cache_lock, flags); + if (domain->qi_batch) + goto out_unlock; + + domain->qi_batch = kzalloc_obj(*domain->qi_batch, GFP_ATOMIC); + if (!domain->qi_batch) + ret = -ENOMEM; +out_unlock: + spin_unlock_irqrestore(&domain->cache_lock, flags); + + return ret; +} + +static int __cache_tag_assign_domain(struct dmar_domain *domain, u16 did, + struct device *dev, ioasid_t pasid) +{ + struct device_domain_info *info = dev_iommu_priv_get(dev); + int ret; + + ret = domain_qi_batch_alloc(domain); + if (ret) + return ret; + + ret = cache_tag_assign(domain, did, dev, pasid, CACHE_TAG_IOTLB); + if (ret || !info->ats_enabled) + return ret; + + ret = cache_tag_assign(domain, did, dev, pasid, CACHE_TAG_DEVTLB); + if (ret) + cache_tag_unassign(domain, did, dev, pasid, CACHE_TAG_IOTLB); + + return ret; +} + +static void __cache_tag_unassign_domain(struct dmar_domain *domain, u16 did, + struct device *dev, ioasid_t pasid) +{ + struct device_domain_info *info = dev_iommu_priv_get(dev); + + cache_tag_unassign(domain, did, dev, pasid, CACHE_TAG_IOTLB); + + if (info->ats_enabled) + cache_tag_unassign(domain, did, dev, pasid, CACHE_TAG_DEVTLB); +} + +static int __cache_tag_assign_parent_domain(struct dmar_domain *domain, u16 did, + struct device *dev, ioasid_t pasid) +{ + struct device_domain_info *info = dev_iommu_priv_get(dev); + int ret; + + ret = domain_qi_batch_alloc(domain); + if (ret) + return ret; + + ret = cache_tag_assign(domain, did, dev, pasid, CACHE_TAG_NESTING_IOTLB); + if (ret || !info->ats_enabled) + return ret; + + ret = cache_tag_assign(domain, did, dev, pasid, CACHE_TAG_NESTING_DEVTLB); + if (ret) + cache_tag_unassign(domain, did, dev, pasid, CACHE_TAG_NESTING_IOTLB); + + return ret; +} + +static void __cache_tag_unassign_parent_domain(struct dmar_domain *domain, u16 did, + struct device *dev, ioasid_t pasid) +{ + struct device_domain_info *info = dev_iommu_priv_get(dev); + + cache_tag_unassign(domain, did, dev, pasid, CACHE_TAG_NESTING_IOTLB); + + if (info->ats_enabled) + cache_tag_unassign(domain, did, dev, pasid, CACHE_TAG_NESTING_DEVTLB); +} + +static u16 domain_get_id_for_dev(struct dmar_domain *domain, struct device *dev) +{ + struct device_domain_info *info = dev_iommu_priv_get(dev); + struct intel_iommu *iommu = info->iommu; + + /* + * The driver assigns different domain IDs for all domains except + * the SVA type. + */ + if (domain->domain.type == IOMMU_DOMAIN_SVA) + return FLPT_DEFAULT_DID; + + return domain_id_iommu(domain, iommu); +} + +/* + * Assign cache tags to a domain when it's associated with a device's + * PASID using a specific domain ID. + * + * On success (return value of 0), cache tags are created and added to the + * domain's cache tag list. On failure (negative return value), an error + * code is returned indicating the reason for the failure. + */ +int cache_tag_assign_domain(struct dmar_domain *domain, + struct device *dev, ioasid_t pasid) +{ + u16 did = domain_get_id_for_dev(domain, dev); + int ret; + + ret = __cache_tag_assign_domain(domain, did, dev, pasid); + if (ret || domain->domain.type != IOMMU_DOMAIN_NESTED) + return ret; + + ret = __cache_tag_assign_parent_domain(domain->s2_domain, did, dev, pasid); + if (ret) + __cache_tag_unassign_domain(domain, did, dev, pasid); + + return ret; +} + +/* + * Remove the cache tags associated with a device's PASID when the domain is + * detached from the device. + * + * The cache tags must be previously assigned to the domain by calling the + * assign interface. + */ +void cache_tag_unassign_domain(struct dmar_domain *domain, + struct device *dev, ioasid_t pasid) +{ + u16 did = domain_get_id_for_dev(domain, dev); + + __cache_tag_unassign_domain(domain, did, dev, pasid); + if (domain->domain.type == IOMMU_DOMAIN_NESTED) + __cache_tag_unassign_parent_domain(domain->s2_domain, did, dev, pasid); +} + +static unsigned long calculate_psi_aligned_address(unsigned long start, + unsigned long last, + unsigned long *size_order) +{ + unsigned int sz_lg2; + + /* Compute a sz_lg2 that spans start and last */ + start &= GENMASK(BITS_PER_LONG - 1, VTD_PAGE_SHIFT); + sz_lg2 = fls_long(start ^ last); + if (sz_lg2 <= 12) { + *size_order = 0; + return start; + } + if (unlikely(sz_lg2 >= BITS_PER_LONG)) { + /* + * MAX_AGAW_PFN_WIDTH triggers full invalidation in all + * downstream users. + */ + *size_order = MAX_AGAW_PFN_WIDTH; + return 0; + } + + *size_order = sz_lg2 - VTD_PAGE_SHIFT; + return start & GENMASK(BITS_PER_LONG - 1, sz_lg2); +} + +static void qi_batch_flush_descs(struct intel_iommu *iommu, struct qi_batch *batch) +{ + if (!iommu || !batch->index) + return; + + qi_submit_sync(iommu, batch->descs, batch->index, 0); + + /* Reset the index value and clean the whole batch buffer. */ + memset(batch, 0, sizeof(*batch)); +} + +static void qi_batch_increment_index(struct intel_iommu *iommu, struct qi_batch *batch) +{ + if (++batch->index == QI_MAX_BATCHED_DESC_COUNT) + qi_batch_flush_descs(iommu, batch); +} + +static void qi_batch_add_iotlb(struct intel_iommu *iommu, u16 did, u64 addr, + unsigned int size_order, u64 type, + struct qi_batch *batch) +{ + qi_desc_iotlb(iommu, did, addr, size_order, type, &batch->descs[batch->index]); + qi_batch_increment_index(iommu, batch); +} + +static void qi_batch_add_dev_iotlb(struct intel_iommu *iommu, u16 sid, u16 pfsid, + u16 qdep, u64 addr, unsigned int mask, + struct qi_batch *batch) +{ + /* + * According to VT-d spec, software is recommended to not submit any Device-TLB + * invalidation requests while address remapping hardware is disabled. + */ + if (!(iommu->gcmd & DMA_GCMD_TE)) + return; + + qi_desc_dev_iotlb(sid, pfsid, qdep, addr, mask, &batch->descs[batch->index]); + qi_batch_increment_index(iommu, batch); +} + +static void qi_batch_add_piotlb_all(struct intel_iommu *iommu, u16 did, + u32 pasid, struct qi_batch *batch) +{ + qi_desc_piotlb_all(did, pasid, &batch->descs[batch->index]); + qi_batch_increment_index(iommu, batch); +} + +static void qi_batch_add_piotlb(struct intel_iommu *iommu, u16 did, u32 pasid, + u64 addr, unsigned int size_order, bool ih, + struct qi_batch *batch) +{ + qi_desc_piotlb(did, pasid, addr, size_order, ih, + &batch->descs[batch->index]); + qi_batch_increment_index(iommu, batch); +} + +static void qi_batch_add_pasid_dev_iotlb(struct intel_iommu *iommu, u16 sid, u16 pfsid, + u32 pasid, u16 qdep, u64 addr, + unsigned int size_order, struct qi_batch *batch) +{ + /* + * According to VT-d spec, software is recommended to not submit any + * Device-TLB invalidation requests while address remapping hardware + * is disabled. + */ + if (!(iommu->gcmd & DMA_GCMD_TE)) + return; + + qi_desc_dev_iotlb_pasid(sid, pfsid, pasid, qdep, addr, size_order, + &batch->descs[batch->index]); + qi_batch_increment_index(iommu, batch); +} + +static bool intel_domain_use_piotlb(struct dmar_domain *domain) +{ + return domain->domain.type == IOMMU_DOMAIN_SVA || + domain->domain.type == IOMMU_DOMAIN_NESTED || + intel_domain_is_fs_paging(domain); +} + +static void cache_tag_flush_iotlb(struct dmar_domain *domain, struct cache_tag *tag, + unsigned long addr, unsigned long mask, int ih) +{ + struct intel_iommu *iommu = tag->iommu; + u64 type = DMA_TLB_PSI_FLUSH; + + if (intel_domain_use_piotlb(domain)) { + if (mask >= MAX_AGAW_PFN_WIDTH) + qi_batch_add_piotlb_all(iommu, tag->domain_id, + tag->pasid, domain->qi_batch); + else + qi_batch_add_piotlb(iommu, tag->domain_id, tag->pasid, + addr, mask, ih, domain->qi_batch); + return; + } + + /* + * Fallback to domain selective flush if no PSI support or the size + * is too big. + */ + if (!cap_pgsel_inv(iommu->cap) || + mask > cap_max_amask_val(iommu->cap)) { + addr = 0; + mask = 0; + ih = 0; + type = DMA_TLB_DSI_FLUSH; + } + + if (ecap_qis(iommu->ecap)) + qi_batch_add_iotlb(iommu, tag->domain_id, addr | ih, mask, type, + domain->qi_batch); + else + __iommu_flush_iotlb(iommu, tag->domain_id, addr | ih, mask, type); +} + +static void cache_tag_flush_devtlb_psi(struct dmar_domain *domain, struct cache_tag *tag, + unsigned long addr, unsigned long mask) +{ + struct intel_iommu *iommu = tag->iommu; + struct device_domain_info *info; + u16 sid; + + info = dev_iommu_priv_get(tag->dev); + sid = PCI_DEVID(info->bus, info->devfn); + + if (tag->pasid == IOMMU_NO_PASID) { + qi_batch_add_dev_iotlb(iommu, sid, info->pfsid, info->ats_qdep, + addr, mask, domain->qi_batch); + if (info->dtlb_extra_inval) + qi_batch_add_dev_iotlb(iommu, sid, info->pfsid, info->ats_qdep, + addr, mask, domain->qi_batch); + return; + } + + qi_batch_add_pasid_dev_iotlb(iommu, sid, info->pfsid, tag->pasid, + info->ats_qdep, addr, mask, domain->qi_batch); + if (info->dtlb_extra_inval) + qi_batch_add_pasid_dev_iotlb(iommu, sid, info->pfsid, tag->pasid, + info->ats_qdep, addr, mask, + domain->qi_batch); +} + +/* + * Invalidates a range of IOVA from @start (inclusive) to @end (inclusive) + * when the memory mappings in the target domain have been modified. + */ +void cache_tag_flush_range(struct dmar_domain *domain, unsigned long start, + unsigned long end, int ih) +{ + struct intel_iommu *iommu = NULL; + unsigned long mask, addr; + struct cache_tag *tag; + unsigned long flags; + + addr = calculate_psi_aligned_address(start, end, &mask); + + spin_lock_irqsave(&domain->cache_lock, flags); + list_for_each_entry(tag, &domain->cache_tags, node) { + if (iommu && iommu != tag->iommu) + qi_batch_flush_descs(iommu, domain->qi_batch); + iommu = tag->iommu; + + switch (tag->type) { + case CACHE_TAG_IOTLB: + case CACHE_TAG_NESTING_IOTLB: + cache_tag_flush_iotlb(domain, tag, addr, mask, ih); + break; + case CACHE_TAG_NESTING_DEVTLB: + /* + * Address translation cache in device side caches the + * result of nested translation. There is no easy way + * to identify the exact set of nested translations + * affected by a change in S2. So just flush the entire + * device cache. + */ + cache_tag_flush_devtlb_psi(domain, tag, 0, MAX_AGAW_PFN_WIDTH); + break; + case CACHE_TAG_DEVTLB: + cache_tag_flush_devtlb_psi(domain, tag, addr, mask); + break; + } + + trace_cache_tag_flush_range(tag, start, end, addr, mask); + } + qi_batch_flush_descs(iommu, domain->qi_batch); + spin_unlock_irqrestore(&domain->cache_lock, flags); +} + +/* + * Invalidates all ranges of IOVA when the memory mappings in the target + * domain have been modified. + */ +void cache_tag_flush_all(struct dmar_domain *domain) +{ + cache_tag_flush_range(domain, 0, ULONG_MAX, 0); +} + +/* + * Invalidate a range of IOVA when new mappings are created in the target + * domain. + * + * - VT-d spec, Section 6.1 Caching Mode: When the CM field is reported as + * Set, any software updates to remapping structures other than first- + * stage mapping requires explicit invalidation of the caches. + * - VT-d spec, Section 6.8 Write Buffer Flushing: For hardware that requires + * write buffer flushing, software must explicitly perform write-buffer + * flushing, if cache invalidation is not required. + */ +void cache_tag_flush_range_np(struct dmar_domain *domain, unsigned long start, + unsigned long end) +{ + struct intel_iommu *iommu = NULL; + unsigned long mask, addr; + struct cache_tag *tag; + unsigned long flags; + + addr = calculate_psi_aligned_address(start, end, &mask); + + spin_lock_irqsave(&domain->cache_lock, flags); + list_for_each_entry(tag, &domain->cache_tags, node) { + if (iommu && iommu != tag->iommu) + qi_batch_flush_descs(iommu, domain->qi_batch); + iommu = tag->iommu; + + if (!cap_caching_mode(iommu->cap) || + intel_domain_is_fs_paging(domain)) { + iommu_flush_write_buffer(iommu); + continue; + } + + if (tag->type == CACHE_TAG_IOTLB || + tag->type == CACHE_TAG_NESTING_IOTLB) + cache_tag_flush_iotlb(domain, tag, addr, mask, 0); + + trace_cache_tag_flush_range_np(tag, start, end, addr, mask); + } + qi_batch_flush_descs(iommu, domain->qi_batch); + spin_unlock_irqrestore(&domain->cache_lock, flags); +} -- cgit v1.3.1