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Schoenherr" , Usama Arif , Anthony Yznaga , Stanislav Kinsburskii , , , Subject: [RFC 10/18] iommu/intel: zap context table entries on kexec Date: Mon, 5 Feb 2024 12:01:55 +0000 Message-ID: <20240205120203.60312-11-jgowans@amazon.com> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20240205120203.60312-1-jgowans@amazon.com> References: <20240205120203.60312-1-jgowans@amazon.com> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ClientProxiedBy: EX19D041UWA001.ant.amazon.com (10.13.139.124) To EX19D014EUC004.ant.amazon.com (10.252.51.182) In the next commit the IOMMU shutdown function will be modified to not actually shut down the IOMMU when doing a kexec. To prevent leaving DMA mappings for non-persistent devices around during kexec we add a function to the kexec flow which iterates though all IOMMU domains and zaps the context entries for the devices belonging to those domain. A list of domains for the IOMMU is added and maintained. --- drivers/iommu/intel/dmar.c | 1 + drivers/iommu/intel/iommu.c | 34 ++++++++++++++++++++++++++++++---- drivers/iommu/intel/iommu.h | 2 ++ 3 files changed, 33 insertions(+), 4 deletions(-) diff --git a/drivers/iommu/intel/dmar.c b/drivers/iommu/intel/dmar.c index 23cb80d62a9a..00f69f40a4ac 100644 --- a/drivers/iommu/intel/dmar.c +++ b/drivers/iommu/intel/dmar.c @@ -1097,6 +1097,7 @@ static int alloc_iommu(struct dmar_drhd_unit *drhd) iommu->segment = drhd->segment; iommu->node = NUMA_NO_NODE; + INIT_LIST_HEAD(&iommu->domains); ver = readl(iommu->reg + DMAR_VER_REG); pr_info("%s: reg_base_addr %llx ver %d:%d cap %llx ecap %llx\n", diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c index 2dd3f055dbce..315c6b7f901c 100644 --- a/drivers/iommu/intel/iommu.c +++ b/drivers/iommu/intel/iommu.c @@ -1831,6 +1831,7 @@ static int domain_attach_iommu(struct dmar_domain *domain, goto err_clear; } domain_update_iommu_cap(domain); + list_add(&domain->domains, &iommu->domains); spin_unlock(&iommu->lock); return 0; @@ -3608,6 +3609,33 @@ static void intel_disable_iommus(void) iommu_disable_translation(iommu); } +void zap_context_table_entries(struct intel_iommu *iommu) +{ + struct context_entry *context; + struct dmar_domain *domain; + struct device_domain_info *device; + int bus, devfn; + u16 did_old; + + list_for_each_entry(domain, &iommu->domains, domains) { + list_for_each_entry(device, &domain->devices, link) { + context = iommu_context_addr(iommu, device->bus, device->devfn, 0); + if (!context || !context_present(context)) + continue; + context_domain_id(context); + context_clear_entry(context); + __iommu_flush_cache(iommu, context, sizeof(*context)); + iommu->flush.flush_context(iommu, + did_old, + (((u16)bus) << 8) | devfn, + DMA_CCMD_MASK_NOBIT, + DMA_CCMD_DEVICE_INVL); + iommu->flush.flush_iotlb(iommu, did_old, 0, 0, + DMA_TLB_DSI_FLUSH); + } + } +} + void intel_iommu_shutdown(void) { struct dmar_drhd_unit *drhd; @@ -3620,10 +3648,8 @@ void intel_iommu_shutdown(void) /* Disable PMRs explicitly here. */ for_each_iommu(iommu, drhd) - iommu_disable_protect_mem_regions(iommu); - - /* Make sure the IOMMUs are switched off */ - intel_disable_iommus(); + zap_context_table_entries(iommu); + return up_write(&dmar_global_lock); } diff --git a/drivers/iommu/intel/iommu.h b/drivers/iommu/intel/iommu.h index a2338e398ba3..4a2f163a86f3 100644 --- a/drivers/iommu/intel/iommu.h +++ b/drivers/iommu/intel/iommu.h @@ -600,6 +600,7 @@ struct dmar_domain { spinlock_t lock; /* Protect device tracking lists */ struct list_head devices; /* all devices' list */ struct list_head dev_pasids; /* all attached pasids */ + struct list_head domains; /* all struct dmar_domains on this IOMMU */ struct dma_pte *pgd; /* virtual address */ int gaw; /* max guest address width */ @@ -700,6 +701,7 @@ struct intel_iommu { void *perf_statistic; struct iommu_pmu *pmu; + struct list_head domains; /* all struct dmar_domains on this IOMMU */ }; /* PCI domain-device relationship */