linux-kernel - [RFC PATCH 08/15] iommu/vt-d: Implement live update preserve_iommu

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250928190624.3735830-9-skhawaja@google.com>
Date: Sun, 28 Sep 2025 19:06:16 +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>, 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, zhuyifei@...gle.com, 
	Chris Li <chrisl@...nel.org>, praan@...gle.com
Subject: [RFC PATCH 08/15] iommu/vt-d: Implement live update preserve_iommu_context

Add implementation of preserve_iommu_context to preserve the root_table
and the associated context tables. Also mark the iommu unit as
preserved.

Signed-off-by: Samiullah Khawaja <skhawaja@...gle.com>
---
 drivers/iommu/intel/iommu.c      |  2 -
 drivers/iommu/intel/iommu.h      |  1 +
 drivers/iommu/intel/liveupdate.c | 80 +++++++++++++++++++++++++++++++-
 3 files changed, 79 insertions(+), 4 deletions(-)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 7035ffca020f..caac4fd9a51e 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -67,8 +67,6 @@ static int force_on = 0;
 static int intel_iommu_tboot_noforce;
 static int no_platform_optin;
 
-#define ROOT_ENTRY_NR (VTD_PAGE_SIZE/sizeof(struct root_entry))
-
 /*
  * Take a root_entry and return the Lower Context Table Pointer (LCTP)
  * if marked present.
diff --git a/drivers/iommu/intel/iommu.h b/drivers/iommu/intel/iommu.h
index 93ac55eb49f0..273d40812d09 100644
--- a/drivers/iommu/intel/iommu.h
+++ b/drivers/iommu/intel/iommu.h
@@ -556,6 +556,8 @@ struct root_entry {
 	u64     lo;
 	u64     hi;
 };
+
+#define ROOT_ENTRY_NR (VTD_PAGE_SIZE / sizeof(struct root_entry))
 
 /*
  * low 64 bits:
diff --git a/drivers/iommu/intel/liveupdate.c b/drivers/iommu/intel/liveupdate.c
index 94aabf025a60..fb214736aa3c 100644
--- a/drivers/iommu/intel/liveupdate.c
+++ b/drivers/iommu/intel/liveupdate.c
@@ -59,11 +59,87 @@ static int preserve_device_state(struct pci_dev *dev, struct device_ser *ser)
 	return 0;
 }
 
+static int unpreserve_iommu_context(struct intel_iommu *iommu, int end)
+{
+	struct context_entry *context;
+	int i;
+
+	if (end < 0)
+		end = ROOT_ENTRY_NR;
+
+	for (i = 0; i < end; i++) {
+		context = iommu_context_addr(iommu, i, 0, 0);
+		if (context)
+			WARN_ON_ONCE(kho_unpreserve_folio(virt_to_folio(context)));
+
+		if (!sm_supported(iommu))
+			continue;
+
+		context = iommu_context_addr(iommu, i, 0x80, 0);
+		if (context)
+			WARN_ON_ONCE(kho_unpreserve_folio(virt_to_folio(context)));
+	}
+
+	return 0;
+}
+
+static int preserve_iommu_context(struct intel_iommu *iommu)
+{
+	struct context_entry *context;
+	int ret;
+	int i;
+
+	for (i = 0; i < ROOT_ENTRY_NR; i++) {
+		context = iommu_context_addr(iommu, i, 0, 0);
+		if (context) {
+			ret = kho_preserve_folio(virt_to_folio(context));
+			if (ret)
+				goto error;
+		}
+
+		if (!sm_supported(iommu))
+			continue;
+
+		context = iommu_context_addr(iommu, i, 0x80, 0);
+		if (context) {
+			ret = kho_preserve_folio(virt_to_folio(context));
+			if (ret)
+				goto error_sm;
+		}
+	}
+
+	return 0;
+
+error_sm:
+	context = iommu_context_addr(iommu, i, 0, 0);
+	WARN_ON_ONCE(kho_unpreserve_folio(virt_to_folio(context)));
+error:
+	WARN_ON_ONCE(unpreserve_iommu_context(iommu, i));
+	return ret;
+}
+
 static int preserve_iommu_state(struct intel_iommu *iommu,
 				struct iommu_unit_ser *ser)
 {
-	pr_warn("Not implemented\n");
-	return 0;
+	int ret;
+
+	spin_lock(&iommu->lock);
+	ret = preserve_iommu_context(iommu);
+	if (ret)
+		goto error;
+
+	ret = kho_preserve_folio(virt_to_folio(iommu->root_entry));
+	if (ret) {
+		unpreserve_iommu_context(iommu, -1);
+		goto error;
+	}
+
+	ser->phys_addr = iommu->reg_phys;
+	ser->root_table = __pa(iommu->root_entry);
+	atomic_set(&iommu->preserved, 1);
+error:
+	spin_unlock(&iommu->lock);
+	return ret;
 }
 
 static void unpreserve_state(struct iommu_ser *ser)
-- 
2.51.0.536.g15c5d4f767-goog