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Message-ID: <20251202230303.1017519-25-skhawaja@google.com>
Date: Tue, 2 Dec 2025 23:02:54 +0000
From: Samiullah Khawaja <skhawaja@...gle.com>
To: David Woodhouse <dwmw2@...radead.org>, Lu Baolu <baolu.lu@...ux.intel.com>,
Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
Pasha Tatashin <pasha.tatashin@...een.com>, Jason Gunthorpe <jgg@...pe.ca>, iommu@...ts.linux.dev
Cc: Samiullah Khawaja <skhawaja@...gle.com>, Robin Murphy <robin.murphy@....com>,
Pratyush Yadav <pratyush@...nel.org>, Kevin Tian <kevin.tian@...el.com>,
Alex Williamson <alex@...zbot.org>, linux-kernel@...r.kernel.org,
Saeed Mahameed <saeedm@...dia.com>, Adithya Jayachandran <ajayachandra@...dia.com>,
Parav Pandit <parav@...dia.com>, Leon Romanovsky <leonro@...dia.com>, William Tu <witu@...dia.com>,
Vipin Sharma <vipinsh@...gle.com>, dmatlack@...gle.com, YiFei Zhu <zhuyifei@...gle.com>,
Chris Li <chrisl@...nel.org>, praan@...gle.com
Subject: [RFC PATCH v2 24/32] iommu/vt-d: restore state of the preserved IOMMU
During boot fetch the preserved state of IOMMU unit and if found then
restore the state. Reuse the root_table that was preserved in the
previous kernel.
Signed-off-by: Samiullah Khawaja <skhawaja@...gle.com>
---
drivers/iommu/intel/iommu.c | 30 ++++++++++++++++++++++++------
drivers/iommu/intel/iommu.h | 2 ++
drivers/iommu/intel/liveupdate.c | 30 ++++++++++++++++++++++++++++++
3 files changed, 56 insertions(+), 6 deletions(-)
diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 84fef81ecf4d..888351f91918 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -224,12 +224,12 @@ static void clear_translation_pre_enabled(struct intel_iommu *iommu)
iommu->flags &= ~VTD_FLAG_TRANS_PRE_ENABLED;
}
-static void init_translation_status(struct intel_iommu *iommu)
+static void init_translation_status(struct intel_iommu *iommu, bool restoring)
{
u32 gsts;
gsts = readl(iommu->reg + DMAR_GSTS_REG);
- if (gsts & DMA_GSTS_TES)
+ if (!restoring && (gsts & DMA_GSTS_TES))
iommu->flags |= VTD_FLAG_TRANS_PRE_ENABLED;
}
@@ -672,10 +672,18 @@ void dmar_fault_dump_ptes(struct intel_iommu *iommu, u16 source_id,
#endif
/* iommu handling */
-static int iommu_alloc_root_entry(struct intel_iommu *iommu)
+static int iommu_alloc_root_entry(struct intel_iommu *iommu, struct iommu_ser *restored_state)
{
struct root_entry *root;
+#if CONFIG_LIVEUPDATE
+ if (restored_state) {
+ intel_iommu_liveupdate_restore_root_table(iommu, restored_state);
+ /* Should not be needed since the entries are already cleaned in last kernel. */
+ __iommu_flush_cache(iommu, iommu->root_entry, ROOT_SIZE);
+ return 0;
+ }
+#endif
root = iommu_alloc_pages_node_sz(iommu->node, GFP_ATOMIC, SZ_4K);
if (!root) {
pr_err("Allocating root entry for %s failed\n",
@@ -1616,6 +1624,7 @@ static int copy_translation_tables(struct intel_iommu *iommu)
static int __init init_dmars(void)
{
+ struct iommu_ser *iommu_ser = NULL;
struct dmar_drhd_unit *drhd;
struct intel_iommu *iommu;
int ret;
@@ -1638,8 +1647,12 @@ static int __init init_dmars(void)
intel_pasid_max_id);
}
+#if IS_ENABLED(CONFIG_LIVEUPDATE)
+ iommu_ser = iommu_get_preserved_data(iommu->reg_phys, IOMMU_INTEL);
+#endif
+
intel_iommu_init_qi(iommu);
- init_translation_status(iommu);
+ init_translation_status(iommu, !!iommu_ser);
if (translation_pre_enabled(iommu) && !is_kdump_kernel()) {
iommu_disable_translation(iommu);
@@ -1653,7 +1666,7 @@ static int __init init_dmars(void)
* we could share the same root & context tables
* among all IOMMU's. Need to Split it later.
*/
- ret = iommu_alloc_root_entry(iommu);
+ ret = iommu_alloc_root_entry(iommu, iommu_ser);
if (ret)
goto free_iommu;
@@ -2112,6 +2125,7 @@ int dmar_parse_one_satc(struct acpi_dmar_header *hdr, void *arg)
static int intel_iommu_add(struct dmar_drhd_unit *dmaru)
{
struct intel_iommu *iommu = dmaru->iommu;
+ struct iommu_ser *iommu_ser = NULL;
int ret;
/*
@@ -2120,7 +2134,11 @@ static int intel_iommu_add(struct dmar_drhd_unit *dmaru)
if (iommu->gcmd & DMA_GCMD_TE)
iommu_disable_translation(iommu);
- ret = iommu_alloc_root_entry(iommu);
+#if IS_ENABLED(CONFIG_LIVEUPDATE)
+ iommu_ser = iommu_get_preserved_data(iommu->reg_phys, IOMMU_INTEL);
+#endif
+
+ ret = iommu_alloc_root_entry(iommu, iommu_ser);
if (ret)
goto out;
diff --git a/drivers/iommu/intel/iommu.h b/drivers/iommu/intel/iommu.h
index 1eb60ce1300f..b0c56e27f167 100644
--- a/drivers/iommu/intel/iommu.h
+++ b/drivers/iommu/intel/iommu.h
@@ -1283,6 +1283,8 @@ int intel_iommu_preserve_device(struct device *dev, struct device_ser *device_se
void intel_iommu_unpreserve_device(struct device *dev, struct device_ser *device_ser);
int intel_iommu_preserve(struct iommu_device *iommu, struct iommu_ser *iommu_ser);
void intel_iommu_unpreserve(struct iommu_device *iommu, struct iommu_ser *iommu_ser);
+void intel_iommu_liveupdate_restore_root_table(struct intel_iommu *iommu,
+ struct iommu_ser *iommu_ser);
bool intel_iommu_liveupdate_clear_context_entries(struct intel_iommu *iommu);
#endif
diff --git a/drivers/iommu/intel/liveupdate.c b/drivers/iommu/intel/liveupdate.c
index 3f8c7f15bc36..140887187084 100644
--- a/drivers/iommu/intel/liveupdate.c
+++ b/drivers/iommu/intel/liveupdate.c
@@ -73,6 +73,36 @@ static int preserve_iommu_context(struct intel_iommu *iommu)
return ret;
}
+static void restore_iommu_context(struct intel_iommu *iommu)
+{
+ struct context_entry *context;
+ int i;
+
+ for (i = 0; i < ROOT_ENTRY_NR; i++) {
+ context = iommu_context_addr(iommu, i, 0, 0);
+ if (context)
+ BUG_ON(!kho_restore_folio(virt_to_phys(context)));
+
+ if (!sm_supported(iommu))
+ continue;
+
+ context = iommu_context_addr(iommu, i, 0x80, 0);
+ if (context)
+ BUG_ON(!kho_restore_folio(virt_to_phys(context)));
+ }
+}
+
+void intel_iommu_liveupdate_restore_root_table(struct intel_iommu *iommu,
+ struct iommu_ser *iommu_ser)
+{
+ BUG_ON(!kho_restore_folio(iommu_ser->intel.root_table));
+ iommu->root_entry = __va(iommu_ser->intel.root_table);
+
+ restore_iommu_context(iommu);
+ pr_info("Restored IOMMU[0x%llx] Root Table at: 0x%llx\n",
+ iommu->reg_phys, iommu_ser->intel.root_table);
+}
+
int intel_iommu_preserve_device(struct device *dev, struct device_ser *device_ser)
{
struct device_domain_info *info = dev_iommu_priv_get(dev);
--
2.52.0.158.g65b55ccf14-goog
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