From a5f7a5bb3b7f28ba7e4fa246775b29a0e5537255 Mon Sep 17 00:00:00 2001 From: Jinke Han Date: Tue, 8 Sep 2026 15:37:42 +0800 Subject: x86/kprobes: Fix crash when probing CS CALL instructions When using eBPF to probe CS CALL instructions within a function, a crash can be triggered. The eBPF tool probes offset 257 of the __hrtimer_run_queues() function: <__hrtimer_run_queues+249>: nopl 0x0(%rax,%rax,1) <__hrtimer_run_queues+254>: mov %r14,%rdi <__hrtimer_run_queues+257>: cs call <__x86_indirect_thunk_r12> <__hrtimer_run_queues+263>: mov %eax,%r12d <__hrtimer_run_queues+266>: xchg %ax,%ax <__hrtimer_run_queues+268>: mov %r13,%rdi Which triggers this crash: BUG: unable to handle page fault for address: 00000000000f41c9 #PF: supervisor write access in kernel mode #PF: error_code(0x0002) - not-present page PGD 0 P4D 0 Oops: 0002 [#1] SMP NOPTI CPU: 1 PID: 0 Comm: swapper/1 Kdump: loaded Tainted: P RIP: 0010:__hrtimer_run_queues+0x106/0x230 Note that __hrtimer_run_queues+0x106 is __hrtimer_run_queues+262, which is at the 6th byte of the above CS CALL instruction. Since the CS CALL instruction occupies 6 bytes, the exception occurred in the middle of that call instruction. The root cause is that when using eBPF tools to probe in the middle of a function, a kprobe with INT3 is used as the underlying implementation. During single-step emulation of the original CALL instruction, int3_emulate_call() assumes that the probed CALL instruction is 5 bytes long. However, the actual CS-prefixed CALL instruction occupies 6 bytes, so it constructs an incorrect exception return address. When the CPU returns from the kprobe handler, the next instruction to be executed is at the address of the last byte of that CS CALL instruction. Coincidentally, starting from that address, the CPU fetches and decodes a completely different instruction, which ultimately triggers a kernel crash. Fix the issue by using the actual instruction length obtained from the instruction decoder when constructing the exception return address, rather than relying on the hardcoded CALL_INSN_SIZE macro. [ mingo: Refined the changelog ] Fixes: 6256e668b7af ("x86/kprobes: Use int3 instead of debug trap for single-step") Suggested-by: Masami Hiramatsu (Google) Signed-off-by: Jinke Han Signed-off-by: Ingo Molnar Reviewed-by: Masami Hiramatsu (Google) Acked-by: Yafang Shao Acked-by: Borislav Petkov Cc: Peter Zijlstra Link: https://patch.msgid.link/20260908073742.GA10517@didi-ThinkCentre-M920t-N000 --- 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