[PATCH v11 2/6] VT-d: Introduce new fields in msi_desc to track binding with guest interrupt

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

msi_msg_to_remap_entry() is buggy when the live IRTE is in posted format. It
wrongly inherits the 'im' field meaning the IRTE is in posted format but
updates all the other fields to remapping format.

There are also two situations that lead to the above issue. One is some callers
really want to change the IRTE to remapped format. The other is some callers
only want to update msi message (e.g. set msi affinity) for they don't aware
that this msi is binded with a guest interrupt. We should suppress update
in the second situation. To distinguish them, straightforwardly, we can let
caller specify which format of IRTE they want update to. It isn't feasible for
making all callers be aware of the binding with guest interrupt will cause a
far more complicated change (including the interfaces exposed to IOAPIC and
MSI). Also some callings happen in interrupt context where we can't acquire
d->event_lock to read struct hvm_pirq_dpci.

This patch introduces two new fields in msi_desc to track binding with a guest
interrupt such that msi_msg_to_remap_entry() can get the binding and update
IRTE accordingly. After that change, pi_update_irte() can utilize
msi_msg_to_remap_entry() to update IRTE to posted format.

Signed-off-by: Feng Wu <feng.wu@intel.com>
Signed-off-by: Chao Gao <chao.gao@intel.com>
---
v11:
- Commit message changes.
- Add code to clear the two new fields introduced in this patch.

v10:
- Newly added.

 xen/arch/x86/msi.c                     |   1 +
 xen/drivers/passthrough/io.c           |   2 +
 xen/drivers/passthrough/vtd/intremap.c | 150 +++++++--------------------------
 xen/include/asm-x86/msi.h              |   2 +
 4 files changed, 36 insertions(+), 119 deletions(-)

diff --git a/xen/arch/x86/msi.c b/xen/arch/x86/msi.c
index a868007..3374cd4 100644
--- a/xen/arch/x86/msi.c
+++ b/xen/arch/x86/msi.c
@@ -578,6 +578,7 @@ static struct msi_desc *alloc_msi_entry(unsigned int nr)
         entry[nr].dev = NULL;
         entry[nr].irq = -1;
         entry[nr].remap_index = -1;
+        entry[nr].pi_desc = NULL;
     }
 
     return entry;
diff --git a/xen/drivers/passthrough/io.c b/xen/drivers/passthrough/io.c
index d53976c..5dbfe53 100644
--- a/xen/drivers/passthrough/io.c
+++ b/xen/drivers/passthrough/io.c
@@ -618,6 +618,8 @@ int pt_irq_destroy_bind(
         else
             what = "bogus";
     }
+    else if ( iommu_intpost && pirq && pirq_dpci->gmsi.posted )
+        pi_update_irte(NULL, pirq, 0);
 
     if ( pirq_dpci && (pirq_dpci->flags & HVM_IRQ_DPCI_MAPPED) &&
          list_empty(&pirq_dpci->digl_list) )
diff --git a/xen/drivers/passthrough/vtd/intremap.c b/xen/drivers/passthrough/vtd/intremap.c
index bfd468b..9bbf0f6 100644
--- a/xen/drivers/passthrough/vtd/intremap.c
+++ b/xen/drivers/passthrough/vtd/intremap.c
@@ -551,12 +551,12 @@ static int msi_msg_to_remap_entry(
     struct iommu *iommu, struct pci_dev *pdev,
     struct msi_desc *msi_desc, struct msi_msg *msg)
 {
-    struct iremap_entry *iremap_entry = NULL, *iremap_entries;
-    struct iremap_entry new_ire;
+    struct iremap_entry *iremap_entry = NULL, *iremap_entries, new_ire = { };
     struct msi_msg_remap_entry *remap_rte;
     unsigned int index, i, nr = 1;
     unsigned long flags;
     struct ir_ctrl *ir_ctrl = iommu_ir_ctrl(iommu);
+    const struct pi_desc *pi_desc = msi_desc->pi_desc;
 
     if ( msi_desc->msi_attrib.type == PCI_CAP_ID_MSI )
         nr = msi_desc->msi.nvec;
@@ -595,33 +595,35 @@ static int msi_msg_to_remap_entry(
     GET_IREMAP_ENTRY(ir_ctrl->iremap_maddr, index,
                      iremap_entries, iremap_entry);
 
-    memcpy(&new_ire, iremap_entry, sizeof(struct iremap_entry));
-
-    /* Set interrupt remapping table entry */
-    new_ire.remap.fpd = 0;
-    new_ire.remap.dm = (msg->address_lo >> MSI_ADDR_DESTMODE_SHIFT) & 0x1;
-    new_ire.remap.tm = (msg->data >> MSI_DATA_TRIGGER_SHIFT) & 0x1;
-    new_ire.remap.dlm = (msg->data >> MSI_DATA_DELIVERY_MODE_SHIFT) & 0x1;
-    /* Hardware require RH = 1 for LPR delivery mode */
-    new_ire.remap.rh = (new_ire.remap.dlm == dest_LowestPrio);
-    new_ire.remap.avail = 0;
-    new_ire.remap.res_1 = 0;
-    new_ire.remap.vector = (msg->data >> MSI_DATA_VECTOR_SHIFT) &
-                            MSI_DATA_VECTOR_MASK;
-    new_ire.remap.res_2 = 0;
-    if ( x2apic_enabled )
-        new_ire.remap.dst = msg->dest32;
+    if ( !pi_desc )
+    {
+        new_ire.remap.dm = msg->address_lo >> MSI_ADDR_DESTMODE_SHIFT;
+        new_ire.remap.tm = msg->data >> MSI_DATA_TRIGGER_SHIFT;
+        new_ire.remap.dlm = msg->data >> MSI_DATA_DELIVERY_MODE_SHIFT;
+        /* Hardware requires RH = 1 for lowest priority delivery mode */
+        new_ire.remap.rh = (new_ire.remap.dlm == dest_LowestPrio);
+        new_ire.remap.vector = (msg->data >> MSI_DATA_VECTOR_SHIFT) &
+                                MSI_DATA_VECTOR_MASK;
+        if ( x2apic_enabled )
+            new_ire.remap.dst = msg->dest32;
+        else
+            new_ire.remap.dst =
+                MASK_EXTR(msg->address_lo, MSI_ADDR_DEST_ID_MASK) << 8;
+        new_ire.remap.p = 1;
+    }
     else
-        new_ire.remap.dst = ((msg->address_lo >> MSI_ADDR_DEST_ID_SHIFT)
-                             & 0xff) << 8;
+    {
+        new_ire.post.im = 1;
+        new_ire.post.vector = msi_desc->gvec;
+        new_ire.post.pda_l = virt_to_maddr(pi_desc) >> (32 - PDA_LOW_BIT);
+        new_ire.post.pda_h = virt_to_maddr(pi_desc) >> 32;
+        new_ire.post.p = 1;
+    }
 
     if ( pdev )
         set_msi_source_id(pdev, &new_ire);
     else
         set_hpet_source_id(msi_desc->hpet_id, &new_ire);
-    new_ire.remap.res_3 = 0;
-    new_ire.remap.res_4 = 0;
-    new_ire.remap.p = 1;    /* finally, set present bit */
 
     /* now construct new MSI/MSI-X rte entry */
     remap_rte = (struct msi_msg_remap_entry *)msg;
@@ -902,42 +904,6 @@ void iommu_disable_x2apic_IR(void)
         disable_qinval(drhd->iommu);
 }
 
-static void setup_posted_irte(
-    struct iremap_entry *new_ire, const struct iremap_entry *old_ire,
-    const struct pi_desc *pi_desc, const uint8_t gvec)
-{
-    memset(new_ire, 0, sizeof(*new_ire));
-
-    /*
-     * 'im' filed decides whether the irte is in posted format (with value 1)
-     * or remapped format (with value 0), if the old irte is in remapped format,
-     * we copy things from remapped part in 'struct iremap_entry', otherwise,
-     * we copy from posted part.
-     */
-    if ( !old_ire->remap.im )
-    {
-        new_ire->post.p = old_ire->remap.p;
-        new_ire->post.fpd = old_ire->remap.fpd;
-        new_ire->post.sid = old_ire->remap.sid;
-        new_ire->post.sq = old_ire->remap.sq;
-        new_ire->post.svt = old_ire->remap.svt;
-    }
-    else
-    {
-        new_ire->post.p = old_ire->post.p;
-        new_ire->post.fpd = old_ire->post.fpd;
-        new_ire->post.sid = old_ire->post.sid;
-        new_ire->post.sq = old_ire->post.sq;
-        new_ire->post.svt = old_ire->post.svt;
-        new_ire->post.urg = old_ire->post.urg;
-    }
-
-    new_ire->post.im = 1;
-    new_ire->post.vector = gvec;
-    new_ire->post.pda_l = virt_to_maddr(pi_desc) >> (32 - PDA_LOW_BIT);
-    new_ire->post.pda_h = virt_to_maddr(pi_desc) >> 32;
-}
-
 /*
  * This function is used to update the IRTE for posted-interrupt
  * when guest changes MSI/MSI-X information.
@@ -946,17 +912,9 @@ int pi_update_irte(const struct vcpu *v, const struct pirq *pirq,
     const uint8_t gvec)
 {
     struct irq_desc *desc;
-    const struct msi_desc *msi_desc;
-    int remap_index;
-    int rc = 0;
-    const struct pci_dev *pci_dev;
-    const struct acpi_drhd_unit *drhd;
-    struct iommu *iommu;
-    struct ir_ctrl *ir_ctrl;
-    struct iremap_entry *iremap_entries = NULL, *p = NULL;
-    struct iremap_entry new_ire, old_ire;
-    const struct pi_desc *pi_desc = &v->arch.hvm_vmx.pi_desc;
-    __uint128_t ret;
+    struct msi_desc *msi_desc;
+    const struct pi_desc *pi_desc = v ? &v->arch.hvm_vmx.pi_desc : NULL;
+    int rc;
 
     desc = pirq_spin_lock_irq_desc(pirq, NULL);
     if ( !desc )
@@ -968,59 +926,13 @@ int pi_update_irte(const struct vcpu *v, const struct pirq *pirq,
         rc = -ENODEV;
         goto unlock_out;
     }
-
-    pci_dev = msi_desc->dev;
-    if ( !pci_dev )
-    {
-        rc = -ENODEV;
-        goto unlock_out;
-    }
-
-    remap_index = msi_desc->remap_index;
+    msi_desc->pi_desc = pi_desc;
+    msi_desc->gvec = gvec;
 
     spin_unlock_irq(&desc->lock);
 
     ASSERT(pcidevs_locked());
-
-    /*
-     * FIXME: For performance reasons we should store the 'iommu' pointer in
-     * 'struct msi_desc' in some other place, so we don't need to waste
-     * time searching it here.
-     */
-    drhd = acpi_find_matched_drhd_unit(pci_dev);
-    if ( !drhd )
-        return -ENODEV;
-
-    iommu = drhd->iommu;
-    ir_ctrl = iommu_ir_ctrl(iommu);
-    if ( !ir_ctrl )
-        return -ENODEV;
-
-    spin_lock_irq(&ir_ctrl->iremap_lock);
-
-    GET_IREMAP_ENTRY(ir_ctrl->iremap_maddr, remap_index, iremap_entries, p);
-
-    old_ire = *p;
-
-    /* Setup/Update interrupt remapping table entry. */
-    setup_posted_irte(&new_ire, &old_ire, pi_desc, gvec);
-    ret = cmpxchg16b(p, &old_ire, &new_ire);
-
-    /*
-     * In the above, we use cmpxchg16 to atomically update the 128-bit IRTE,
-     * and the hardware cannot update the IRTE behind us, so the return value
-     * of cmpxchg16 should be the same as old_ire. This ASSERT validate it.
-     */
-    ASSERT(ret == old_ire.val);
-
-    iommu_flush_cache_entry(p, sizeof(*p));
-    iommu_flush_iec_index(iommu, 0, remap_index);
-
-    unmap_vtd_domain_page(iremap_entries);
-
-    spin_unlock_irq(&ir_ctrl->iremap_lock);
-
-    return 0;
+    return iommu_update_ire_from_msi(msi_desc, &msi_desc->msg);
 
  unlock_out:
     spin_unlock_irq(&desc->lock);
diff --git a/xen/include/asm-x86/msi.h b/xen/include/asm-x86/msi.h
index 9c02945..fc9ab04 100644
--- a/xen/include/asm-x86/msi.h
+++ b/xen/include/asm-x86/msi.h
@@ -118,6 +118,8 @@ struct msi_desc {
 	struct msi_msg msg;		/* Last set MSI message */
 
 	int remap_index;		/* index in interrupt remapping table */
+	const struct pi_desc *pi_desc;	/* pointer to posted descriptor */
+	uint8_t gvec;			/* guest vector. valid when pi_desc isn't NULL */
 };
 
 /*
-- 
1.8.3.1


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