[PATCH v4 14/28] x86/vvtd: Handle interrupt translation faults

[Chao Gao <chao.gao@intel.com>]

Interrupt translation faults are non-recoverable fault. When faults
are triggered, it needs to populate fault info to Fault Recording
Registers and inject msi interrupt to notify guest IOMMU driver
to deal with faults.

This patch emulates hardware's handling interrupt translation
faults (more information about the process can be found in VT-d spec,
chipter "Translation Faults", section "Non-Recoverable Fault
Reporting" and section "Non-Recoverable Logging").
Specifically, viommu_record_fault() records the fault information and
viommu_report_non_recoverable_fault() reports faults to software.
Currently, only Primary Fault Logging is supported and the Number of
Fault-recording Registers is 1.

Signed-off-by: Chao Gao <chao.gao@intel.com>
Signed-off-by: Lan Tianyu <tianyu.lan@intel.com>

---
v4:
 - introduce a lock to protect fault-event related regs
---
 xen/drivers/passthrough/vtd/iommu.h |  51 ++++++-
 xen/drivers/passthrough/vtd/vvtd.c  | 288 +++++++++++++++++++++++++++++++++++-
 2 files changed, 333 insertions(+), 6 deletions(-)

diff --git a/xen/drivers/passthrough/vtd/iommu.h b/xen/drivers/passthrough/vtd/iommu.h
index 82edd2a..dc2df75 100644
--- a/xen/drivers/passthrough/vtd/iommu.h
+++ b/xen/drivers/passthrough/vtd/iommu.h
@@ -196,26 +196,67 @@
 #define DMA_CCMD_CAIG_MASK(x) (((u64)x) & ((u64) 0x3 << 59))
 
 /* FECTL_REG */
-#define DMA_FECTL_IM        ((uint32_t)1 << 31)
+#define DMA_FECTL_IM_SHIFT  31
+#define DMA_FECTL_IP_SHIFT  30
+#define DMA_FECTL_IM        ((uint32_t)1 << DMA_FECTL_IM_SHIFT)
+#define DMA_FECTL_IP        ((uint32_t)1 << DMA_FECTL_IP_SHIFT)
 
 /* FSTS_REG */
-#define DMA_FSTS_PFO        ((uint32_t)1 << 0)
-#define DMA_FSTS_PPF        ((uint32_t)1 << 1)
+#define DMA_FSTS_PFO_SHIFT  0
+#define DMA_FSTS_PPF_SHIFT  1
+#define DMA_FSTS_PRO_SHIFT  7
+
+#define DMA_FSTS_PFO        ((uint32_t)1 << DMA_FSTS_PFO_SHIFT)
+#define DMA_FSTS_PPF        ((uint32_t)1 << DMA_FSTS_PPF_SHIFT)
 #define DMA_FSTS_AFO        ((uint32_t)1 << 2)
 #define DMA_FSTS_APF        ((uint32_t)1 << 3)
 #define DMA_FSTS_IQE        ((uint32_t)1 << 4)
 #define DMA_FSTS_ICE        ((uint32_t)1 << 5)
 #define DMA_FSTS_ITE        ((uint32_t)1 << 6)
-#define DMA_FSTS_FAULTS    DMA_FSTS_PFO | DMA_FSTS_PPF | DMA_FSTS_AFO | DMA_FSTS_APF | DMA_FSTS_IQE | DMA_FSTS_ICE | DMA_FSTS_ITE
+#define DMA_FSTS_PRO        ((uint32_t)1 << DMA_FSTS_PRO_SHIFT)
+#define DMA_FSTS_FAULTS     (DMA_FSTS_PFO | DMA_FSTS_PPF | DMA_FSTS_AFO | \
+                             DMA_FSTS_APF | DMA_FSTS_IQE | DMA_FSTS_ICE | \
+                             DMA_FSTS_ITE | DMA_FSTS_PRO)
+#define DMA_FSTS_RW1CS      (DMA_FSTS_PFO | DMA_FSTS_AFO | DMA_FSTS_APF | \
+                             DMA_FSTS_IQE | DMA_FSTS_ICE | DMA_FSTS_ITE | \
+                             DMA_FSTS_PRO)
 #define dma_fsts_fault_record_index(s) (((s) >> 8) & 0xff)
 
 /* FRCD_REG, 32 bits access */
-#define DMA_FRCD_F (((u64)1) << 31)
+#define DMA_FRCD_LEN            0x10
+#define DMA_FRCD2_OFFSET        0x8
+#define DMA_FRCD3_OFFSET        0xc
+#define DMA_FRCD_F_SHIFT        31
+#define DMA_FRCD_F ((u64)1 << DMA_FRCD_F_SHIFT)
 #define dma_frcd_type(d) ((d >> 30) & 1)
 #define dma_frcd_fault_reason(c) (c & 0xff)
 #define dma_frcd_source_id(c) (c & 0xffff)
 #define dma_frcd_page_addr(d) (d & (((u64)-1) << 12)) /* low 64 bit */
 
+struct vtd_fault_record_register
+{
+    union {
+        struct {
+            uint64_t lo;
+            uint64_t hi;
+        } bits;
+        struct {
+            uint64_t rsvd0          :12,
+                     fault_info     :52;
+            uint64_t source_id      :16,
+                     rsvd1          :9,
+                     pmr            :1,  /* Privilege Mode Requested */
+                     exe            :1,  /* Execute Permission Requested */
+                     pasid_p        :1,  /* PASID Present */
+                     fault_reason   :8,  /* Fault Reason */
+                     pasid_val      :20, /* PASID Value */
+                     addr_type      :2,  /* Address Type */
+                     type           :1,  /* Type. (0) Write (1) Read/AtomicOp */
+                     fault          :1;  /* Fault */
+        } fields;
+    };
+};
+
 /* Interrupt remapping transition faults */
 #define VTD_FR_IR_REQ_RSVD      0x20
 #define VTD_FR_IR_INDEX_OVER    0x21
diff --git a/xen/drivers/passthrough/vtd/vvtd.c b/xen/drivers/passthrough/vtd/vvtd.c
index d3dec01..83805d1 100644
--- a/xen/drivers/passthrough/vtd/vvtd.c
+++ b/xen/drivers/passthrough/vtd/vvtd.c
@@ -43,6 +43,7 @@
 struct hvm_hw_vvtd {
     bool eim_enabled;
     bool intremap_enabled;
+    uint32_t fault_index;
 
     /* Interrupt remapping table base gfn and the max of entries */
     uint16_t irt_max_entry;
@@ -58,6 +59,12 @@ struct vvtd {
     struct domain *domain;
     /* # of in-flight interrupts */
     atomic_t inflight_intr;
+    /*
+     * This lock protects fault-event related registers (DMAR_FEXXX_REG).
+     * It's used for draining in-flight fault events before responding
+     * guest's programming to those registers.
+     */
+    spinlock_t fe_lock;
 
     struct hvm_hw_vvtd hw;
     void *irt_base;
@@ -87,6 +94,21 @@ boolean_runtime_param("viommu_verbose", viommu_verbose);
 #endif
 
 #define VVTD_REG_POS(vvtd, offset) &(vvtd->hw.regs[offset/sizeof(uint32_t)])
+static inline int vvtd_test_and_set_bit(struct vvtd *vvtd, uint32_t reg, int nr)
+{
+    return test_and_set_bit(nr, VVTD_REG_POS(vvtd, reg));
+}
+
+static inline int vvtd_test_and_clear_bit(struct vvtd *vvtd, uint32_t reg,
+                                          int nr)
+{
+    return test_and_clear_bit(nr, VVTD_REG_POS(vvtd, reg));
+}
+
+static inline int vvtd_test_bit(struct vvtd *vvtd, uint32_t reg, int nr)
+{
+    return test_bit(nr, VVTD_REG_POS(vvtd, reg));
+}
 
 static inline void vvtd_set_bit(struct vvtd *vvtd, uint32_t reg, int nr)
 {
@@ -238,6 +260,30 @@ static int vvtd_delivery(struct domain *d, uint8_t vector,
     return 0;
 }
 
+static void vvtd_generate_interrupt(const struct vvtd *vvtd, uint64_t addr,
+                                    uint32_t data)
+{
+    bool dm = addr & MSI_ADDR_DESTMODE_MASK;
+    uint32_t dest = MASK_EXTR(addr, MSI_ADDR_DEST_ID_MASK);
+    uint8_t dlm = MASK_EXTR(data, MSI_DATA_DELIVERY_MODE_MASK);
+    uint8_t tm = MASK_EXTR(data, MSI_DATA_TRIGGER_MASK);
+    uint8_t vector = data & MSI_DATA_VECTOR_MASK;
+
+    vvtd_debug("d%d: generating msi %lx %x\n", vvtd->domain->domain_id, addr,
+               data);
+
+    if ( vvtd->hw.eim_enabled )
+        dest |= (addr >> 40) << 8;
+
+    vvtd_delivery(vvtd->domain, vector, dest, dm, dlm, tm);
+}
+
+static void vvtd_notify_fault(const struct vvtd *vvtd)
+{
+    vvtd_generate_interrupt(vvtd, vvtd_get_reg_quad(vvtd, DMAR_FEADDR_REG),
+                            vvtd_get_reg(vvtd, DMAR_FEDATA_REG));
+}
+
 /* Computing the IRTE index for a given interrupt request. When success, return
  * 0 and set index to reference the corresponding IRTE. Otherwise, return < 0,
  * i.e. -1 when the irq request isn't an remapping format.
@@ -290,6 +336,198 @@ static inline uint32_t irte_dest(struct vvtd *vvtd, uint32_t dest)
                                 : MASK_EXTR(dest, IRTE_xAPIC_DEST_MASK);
 }
 
+static void vvtd_report_non_recoverable_fault(struct vvtd *vvtd, int reason)
+{
+    uint32_t fsts = vvtd_get_reg(vvtd, DMAR_FSTS_REG);
+
+    vvtd_set_bit(vvtd, DMAR_FSTS_REG, reason);
+
+    /*
+     * Accoroding to VT-d spec "Non-Recoverable Fault Event" chapter, if
+     * there are any previously reported interrupt conditions that are yet to
+     * be sevices by software, the Fault Event interrrupt is not generated.
+     */
+    if ( fsts & DMA_FSTS_FAULTS )
+        return;
+
+    vvtd_set_bit(vvtd, DMAR_FECTL_REG, DMA_FECTL_IP_SHIFT);
+    if ( !vvtd_test_bit(vvtd, DMAR_FECTL_REG, DMA_FECTL_IM_SHIFT) )
+    {
+        vvtd_notify_fault(vvtd);
+        vvtd_clear_bit(vvtd, DMAR_FECTL_REG, DMA_FECTL_IP_SHIFT);
+    }
+}
+
+static void vvtd_update_ppf(struct vvtd *vvtd)
+{
+    int i;
+    uint64_t cap = vvtd_get_reg_quad(vvtd, DMAR_CAP_REG);
+    unsigned int base = cap_fault_reg_offset(cap);
+
+    for ( i = 0; i < cap_num_fault_regs(cap); i++ )
+    {
+        if ( vvtd_test_bit(vvtd, base + i * DMA_FRCD_LEN + DMA_FRCD3_OFFSET,
+                           DMA_FRCD_F_SHIFT) )
+        {
+            vvtd_report_non_recoverable_fault(vvtd, DMA_FSTS_PPF_SHIFT);
+            return;
+        }
+    }
+    /*
+     * No Primary Fault is in Fault Record Registers, thus clear PPF bit in
+     * FSTS.
+     */
+    vvtd_clear_bit(vvtd, DMAR_FSTS_REG, DMA_FSTS_PPF_SHIFT);
+
+    /* If no fault is in FSTS, clear pending bit in FECTL. */
+    if ( !(vvtd_get_reg(vvtd, DMAR_FSTS_REG) & DMA_FSTS_FAULTS) )
+        vvtd_clear_bit(vvtd, DMAR_FECTL_REG, DMA_FECTL_IP_SHIFT);
+}
+
+/*
+ * Commit a fault to emulated Fault Record Registers.
+ */
+static void vvtd_commit_frcd(struct vvtd *vvtd, int idx,
+                             const struct vtd_fault_record_register *frcd)
+{
+    unsigned int base = cap_fault_reg_offset(
+                            vvtd_get_reg_quad(vvtd, DMAR_CAP_REG));
+
+    vvtd_set_reg_quad(vvtd, base + idx * DMA_FRCD_LEN, frcd->bits.lo);
+    vvtd_set_reg_quad(vvtd, base + idx * DMA_FRCD_LEN + 8, frcd->bits.hi);
+    vvtd_update_ppf(vvtd);
+}
+
+/*
+ * Allocate a FRCD for the caller. If success, return the FRI. Or, return -1
+ * when failure.
+ */
+static int vvtd_alloc_frcd(struct vvtd *vvtd)
+{
+    int prev;
+    uint64_t cap = vvtd_get_reg_quad(vvtd, DMAR_CAP_REG);
+    unsigned int base = cap_fault_reg_offset(cap);
+
+    /* Set the F bit to indicate the FRCD is in use. */
+    if ( !vvtd_test_and_set_bit(vvtd,
+                                base + vvtd->hw.fault_index * DMA_FRCD_LEN +
+                                DMA_FRCD3_OFFSET, DMA_FRCD_F_SHIFT) )
+    {
+        prev = vvtd->hw.fault_index;
+        vvtd->hw.fault_index = (prev + 1) % cap_num_fault_regs(cap);
+        return vvtd->hw.fault_index;
+    }
+    return -ENOMEM;
+}
+
+static void vvtd_free_frcd(struct vvtd *vvtd, int i)
+{
+    unsigned int base = cap_fault_reg_offset(
+                            vvtd_get_reg_quad(vvtd, DMAR_CAP_REG));
+
+    vvtd_clear_bit(vvtd, base + i * DMA_FRCD_LEN + DMA_FRCD3_OFFSET,
+                   DMA_FRCD_F_SHIFT);
+}
+
+static int vvtd_record_fault(struct vvtd *vvtd,
+                             const struct arch_irq_remapping_request *request,
+                             int reason)
+{
+    struct vtd_fault_record_register frcd;
+    int fault_index;
+    uint32_t irt_index;
+
+    spin_lock(&vvtd->fe_lock);
+    switch(reason)
+    {
+    case VTD_FR_IR_REQ_RSVD:
+    case VTD_FR_IR_INDEX_OVER:
+    case VTD_FR_IR_ENTRY_P:
+    case VTD_FR_IR_ROOT_INVAL:
+    case VTD_FR_IR_IRTE_RSVD:
+    case VTD_FR_IR_REQ_COMPAT:
+    case VTD_FR_IR_SID_ERR:
+        if ( vvtd_test_bit(vvtd, DMAR_FSTS_REG, DMA_FSTS_PFO_SHIFT) )
+            goto out;
+
+        /* No available Fault Record means Fault overflowed */
+        fault_index = vvtd_alloc_frcd(vvtd);
+        if ( fault_index < 0 )
+        {
+            vvtd_report_non_recoverable_fault(vvtd, DMA_FSTS_PFO_SHIFT);
+            goto out;
+        }
+        memset(&frcd, 0, sizeof(frcd));
+        frcd.fields.fault_reason = reason;
+        if ( irq_remapping_request_index(request, &irt_index) )
+            goto out;
+        frcd.fields.fault_info = irt_index;
+        frcd.fields.source_id = request->source_id;
+        frcd.fields.fault = 1;
+        vvtd_commit_frcd(vvtd, fault_index, &frcd);
+        break;
+
+    default:
+        vvtd_debug("d%d: can't handle vvtd fault (reason 0x%x)",
+                   vvtd->domain->domain_id, reason);
+        break;
+    }
+
+ out:
+    spin_unlock(&vvtd->fe_lock);
+    return X86EMUL_OKAY;
+}
+
+static int vvtd_write_frcd3(struct vvtd *vvtd, uint32_t val)
+{
+    /* Writing a 1 means clear fault */
+    if ( val & DMA_FRCD_F )
+    {
+        vvtd_free_frcd(vvtd, 0);
+        vvtd_update_ppf(vvtd);
+    }
+    return X86EMUL_OKAY;
+}
+
+static void vvtd_write_fectl(struct vvtd *vvtd, uint32_t val)
+{
+    /*
+     * Only DMA_FECTL_IM bit is writable. Generate pending event when unmask.
+     */
+    if ( !(val & DMA_FECTL_IM) )
+    {
+        /* Clear IM */
+        vvtd_clear_bit(vvtd, DMAR_FECTL_REG, DMA_FECTL_IM_SHIFT);
+        if ( vvtd_test_and_clear_bit(vvtd, DMAR_FECTL_REG, DMA_FECTL_IP_SHIFT) )
+            vvtd_notify_fault(vvtd);
+    }
+    else
+        vvtd_set_bit(vvtd, DMAR_FECTL_REG, DMA_FECTL_IM_SHIFT);
+}
+
+static void vvtd_write_fsts(struct vvtd *vvtd, uint32_t val)
+{
+    int i, max_fault_index = DMA_FSTS_PRO_SHIFT;
+    uint64_t bits_to_clear = val & DMA_FSTS_RW1CS;
+
+    if ( bits_to_clear )
+    {
+        i = find_first_bit(&bits_to_clear, max_fault_index / 8 + 1);
+        while ( i <= max_fault_index )
+        {
+            vvtd_clear_bit(vvtd, DMAR_FSTS_REG, i);
+            i = find_next_bit(&bits_to_clear, max_fault_index / 8 + 1, i + 1);
+        }
+    }
+
+    /*
+     * Clear IP field when all status fields in the Fault Status Register
+     * being clear.
+     */
+    if ( !((vvtd_get_reg(vvtd, DMAR_FSTS_REG) & DMA_FSTS_FAULTS)) )
+        vvtd_clear_bit(vvtd, DMAR_FECTL_REG, DMA_FECTL_IP_SHIFT);
+}
+
 static void write_gcmd_ire(struct vvtd *vvtd, uint32_t val)
 {
     bool set = val & DMA_GCMD_IRE;
@@ -391,11 +629,47 @@ static int vvtd_read(struct vcpu *v, unsigned long addr,
     return X86EMUL_OKAY;
 }
 
+static void vvtd_write_fault_regs(struct vvtd *vvtd, unsigned long val,
+                                  unsigned int offset, unsigned int len)
+{
+    unsigned int fault_offset = cap_fault_reg_offset(
+                                    vvtd_get_reg_quad(vvtd, DMAR_CAP_REG));
+
+    spin_lock(&vvtd->fe_lock);
+    for ( ; len ; len -= 4, offset += 4, val = val >> 32)
+    {
+        switch ( offset )
+        {
+        case DMAR_FSTS_REG:
+            vvtd_write_fsts(vvtd, val);
+            break;
+
+        case DMAR_FECTL_REG:
+            vvtd_write_fectl(vvtd, val);
+            break;
+
+        case DMAR_FEDATA_REG:
+        case DMAR_FEADDR_REG:
+        case DMAR_FEUADDR_REG:
+            vvtd_set_reg(vvtd, offset, val);
+            break;
+
+        default:
+            if ( offset == (fault_offset + DMA_FRCD3_OFFSET) )
+                 vvtd_write_frcd3(vvtd, val);
+            break;
+        }
+    }
+    spin_unlock(&vvtd->fe_lock);
+}
+
 static int vvtd_write(struct vcpu *v, unsigned long addr,
                       unsigned int len, unsigned long val)
 {
     struct vvtd *vvtd = domain_vvtd(v->domain);
     unsigned int offset = addr - vvtd->base_addr;
+    unsigned int fault_offset = cap_fault_reg_offset(
+                                    vvtd_get_reg_quad(vvtd, DMAR_CAP_REG));
 
     vvtd_info("Write offset %x len %d val %lx\n", offset, len, val);
 
@@ -419,7 +693,18 @@ static int vvtd_write(struct vcpu *v, unsigned long addr,
         vvtd_set_reg(vvtd, offset, val);
         break;
 
+    case DMAR_FSTS_REG:
+    case DMAR_FECTL_REG:
+    case DMAR_FEDATA_REG:
+    case DMAR_FEADDR_REG:
+    case DMAR_FEUADDR_REG:
+        vvtd_write_fault_regs(vvtd, val, offset, len);
+        break;
+
     default:
+        if ( (offset == (fault_offset + DMA_FRCD2_OFFSET)) ||
+             (offset == (fault_offset + DMA_FRCD3_OFFSET)) )
+            vvtd_write_fault_regs(vvtd, val, offset, len);
         break;
     }
 
@@ -448,7 +733,7 @@ static void vvtd_handle_fault(struct vvtd *vvtd,
     case VTD_FR_IR_REQ_RSVD:
     case VTD_FR_IR_INDEX_OVER:
     case VTD_FR_IR_ROOT_INVAL:
-        /* TODO: handle fault (e.g. record and report this fault to VM */
+        vvtd_record_fault(vvtd, irq, fault);
         break;
 
     default:
@@ -607,6 +892,7 @@ static int vvtd_create(struct domain *d, struct viommu *viommu)
     vvtd->base_addr = viommu->base_address;
     vvtd->domain = d;
     register_mmio_handler(d, &vvtd_mmio_ops);
+    spin_lock_init(&vvtd->fe_lock);
 
     viommu->priv = vvtd;
 
-- 
1.8.3.1


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