Intel-IOMMU, intr-remap: source-id checking

To support domain-isolation usages, the platform hardware must be
capable of uniquely identifying the requestor (source-id) for each
interrupt message. Without source-id checking for interrupt remapping
, a rouge guest/VM with assigned devices can launch interrupt attacks
to bring down anothe guest/VM or the VMM itself.

This patch adds source-id checking for interrupt remapping, and then
really isolates interrupts for guests/VMs with assigned devices.

Because PCI subsystem is not initialized yet when set up IOAPIC
entries, use read_pci_config_byte to access PCI config space directly.

Signed-off-by: Weidong Han <weidong.han@intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

4 files changed, 136 insertions, 3 deletions

diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index b7a79207295e..4d0216fcb36c 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -1414,6 +1414,9 @@ int setup_ioapic_entry(int apic_id, int irq,
                 irte.vector = vector;
                 irte.dest_id = IRTE_DEST(destination);
 
+                /* Set source-id of interrupt request */
+                set_ioapic_sid(&irte, apic_id);
+
                 modify_irte(irq, &irte);
 
                 ir_entry->index2 = (index >> 15) & 0x1;
@@ -3290,6 +3293,9 @@ static int msi_compose_msg(struct pci_dev *pdev, unsigned int irq, struct msi_ms
                 irte.vector = cfg->vector;
                 irte.dest_id = IRTE_DEST(dest);
 
+                /* Set source-id of interrupt request */
+                set_msi_sid(&irte, pdev);
+
                 modify_irte(irq, &irte);
 
                 msg->address_hi = MSI_ADDR_BASE_HI;
diff --git a/drivers/pci/intr_remapping.c b/drivers/pci/intr_remapping.c
index 44025a0c2bb6..4f5b8712931f 100644
--- a/drivers/pci/intr_remapping.c
+++ b/drivers/pci/intr_remapping.c
@@ -10,6 +10,8 @@
 #include <linux/intel-iommu.h>
 #include "intr_remapping.h"
 #include <acpi/acpi.h>
+#include <asm/pci-direct.h>
+#include "pci.h"
 
 static struct ioapic_scope ir_ioapic[MAX_IO_APICS];
 static int ir_ioapic_num;
@@ -418,6 +420,91 @@ int free_irte(int irq)
         return rc;
 }
 
+/*
+ * source validation type
+ */
+#define SVT_NO_VERIFY           0x0  /* no verification is required */
+#define SVT_VERIFY_SID_SQ       0x1  /* verify using SID and SQ fiels */
+#define SVT_VERIFY_BUS          0x2  /* verify bus of request-id */
+
+/*
+ * source-id qualifier
+ */
+#define SQ_ALL_16       0x0  /* verify all 16 bits of request-id */
+#define SQ_13_IGNORE_1  0x1  /* verify most significant 13 bits, ignore
+                              * the third least significant bit
+                              */
+#define SQ_13_IGNORE_2  0x2  /* verify most significant 13 bits, ignore
+                              * the second and third least significant bits
+                              */
+#define SQ_13_IGNORE_3  0x3  /* verify most significant 13 bits, ignore
+                              * the least three significant bits
+                              */
+
+/*
+ * set SVT, SQ and SID fields of irte to verify
+ * source ids of interrupt requests
+ */
+static void set_irte_sid(struct irte *irte, unsigned int svt,
+                         unsigned int sq, unsigned int sid)
+{
+        irte->svt = svt;
+        irte->sq = sq;
+        irte->sid = sid;
+}
+
+int set_ioapic_sid(struct irte *irte, int apic)
+{
+        int i;
+        u16 sid = 0;
+
+        if (!irte)
+                return -1;
+
+        for (i = 0; i < MAX_IO_APICS; i++) {
+                if (ir_ioapic[i].id == apic) {
+                        sid = (ir_ioapic[i].bus << 8) | ir_ioapic[i].devfn;
+                        break;
+                }
+        }
+
+        if (sid == 0) {
+                pr_warning("Failed to set source-id of IOAPIC (%d)\n", apic);
+                return -1;
+        }
+
+        set_irte_sid(irte, 1, 0, sid);
+
+        return 0;
+}
+
+int set_msi_sid(struct irte *irte, struct pci_dev *dev)
+{
+        struct pci_dev *bridge;
+
+        if (!irte || !dev)
+                return -1;
+
+        /* PCIe device or Root Complex integrated PCI device */
+        if (dev->is_pcie || !dev->bus->parent) {
+                set_irte_sid(irte, SVT_VERIFY_SID_SQ, SQ_ALL_16,
+                             (dev->bus->number << 8) | dev->devfn);
+                return 0;
+        }
+
+        bridge = pci_find_upstream_pcie_bridge(dev);
+        if (bridge) {
+                if (bridge->is_pcie) /* this is a PCIE-to-PCI/PCIX bridge */
+                        set_irte_sid(irte, SVT_VERIFY_BUS, SQ_ALL_16,
+                                (bridge->bus->number << 8) | dev->bus->number);
+                else /* this is a legacy PCI bridge */
+                        set_irte_sid(irte, SVT_VERIFY_SID_SQ, SQ_ALL_16,
+                                (bridge->bus->number << 8) | bridge->devfn);
+        }
+
+        return 0;
+}
+
 static void iommu_set_intr_remapping(struct intel_iommu *iommu, int mode)
 {
         u64 addr;
@@ -624,6 +711,35 @@ error:
         return -1;
 }
 
+static void ir_parse_one_ioapic_scope(struct acpi_dmar_device_scope *scope,
+                                      struct intel_iommu *iommu)
+{
+        struct acpi_dmar_pci_path *path;
+        u8 bus;
+        int count;
+
+        bus = scope->bus;
+        path = (struct acpi_dmar_pci_path *)(scope + 1);
+        count = (scope->length - sizeof(struct acpi_dmar_device_scope))
+                / sizeof(struct acpi_dmar_pci_path);
+
+        while (--count > 0) {
+                /*
+                 * Access PCI directly due to the PCI
+                 * subsystem isn't initialized yet.
+                 */
+                bus = read_pci_config_byte(bus, path->dev, path->fn,
+                                           PCI_SECONDARY_BUS);
+                path++;
+        }
+
+        ir_ioapic[ir_ioapic_num].bus   = bus;
+        ir_ioapic[ir_ioapic_num].devfn = PCI_DEVFN(path->dev, path->fn);
+        ir_ioapic[ir_ioapic_num].iommu = iommu;
+        ir_ioapic[ir_ioapic_num].id    = scope->enumeration_id;
+        ir_ioapic_num++;
+}
+
 static int ir_parse_ioapic_scope(struct acpi_dmar_header *header,
                                  struct intel_iommu *iommu)
 {
@@ -648,9 +764,7 @@ static int ir_parse_ioapic_scope(struct acpi_dmar_header *header,
                                " 0x%Lx\n", scope->enumeration_id,
                                drhd->address);
 
-                        ir_ioapic[ir_ioapic_num].iommu = iommu;
-                        ir_ioapic[ir_ioapic_num].id = scope->enumeration_id;
-                        ir_ioapic_num++;
+                        ir_parse_one_ioapic_scope(scope, iommu);
                 }
                 start += scope->length;
         }
diff --git a/drivers/pci/intr_remapping.h b/drivers/pci/intr_remapping.h
index ca48f0df8ac9..63a263c18415 100644
--- a/drivers/pci/intr_remapping.h
+++ b/drivers/pci/intr_remapping.h
@@ -3,6 +3,8 @@
 struct ioapic_scope {
         struct intel_iommu *iommu;
         unsigned int id;
+        unsigned int bus;       /* PCI bus number */
+        unsigned int devfn;     /* PCI devfn number */
 };
 
 #define IR_X2APIC_MODE(mode) (mode ? (1 << 11) : 0)
diff --git a/include/linux/dmar.h b/include/linux/dmar.h
index 1731fb5fd775..4a2b162c256a 100644
--- a/include/linux/dmar.h
+++ b/include/linux/dmar.h
@@ -126,6 +126,8 @@ extern int free_irte(int irq);
 extern int irq_remapped(int irq);
 extern struct intel_iommu *map_dev_to_ir(struct pci_dev *dev);
 extern struct intel_iommu *map_ioapic_to_ir(int apic);
+extern int set_ioapic_sid(struct irte *irte, int apic);
+extern int set_msi_sid(struct irte *irte, struct pci_dev *dev);
 #else
 static inline int alloc_irte(struct intel_iommu *iommu, int irq, u16 count)
 {
@@ -156,6 +158,15 @@ static inline struct intel_iommu *map_ioapic_to_ir(int apic)
 {
         return NULL;
 }
+static inline int set_ioapic_sid(struct irte *irte, int apic)
+{
+        return 0;
+}
+static inline int set_msi_sid(struct irte *irte, struct pci_dev *dev)
+{
+        return 0;
+}
+
 #define irq_remapped(irq)               (0)
 #define enable_intr_remapping(mode)     (-1)
 #define disable_intr_remapping()        (0)