[Xen-devel] [PATCH v9 11/17] vt-d: Add API to update IRTE when VT-d PI is used

[Feng Wu <feng.wu@xxxxxxxxx>]

This patch adds an API which is used to update the IRTE
for posted-interrupt when guest changes MSI/MSI-X information.

CC: Yang Zhang <yang.z.zhang@xxxxxxxxx>
CC: Kevin Tian <kevin.tian@xxxxxxxxx>
CC: Keir Fraser <keir@xxxxxxx>
CC: Jan Beulich <jbeulich@xxxxxxxx>
CC: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Signed-off-by: Feng Wu <feng.wu@xxxxxxxxx>
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
---
v8:
- Some minor adjustment

v7:
- Remove __uint128_t cast
- Remove Kevin's Ack due to a bug fix for v6
- Reword some comments
- Setup posted IRTE from zeroed structure

v6:
- In some error cases, the desc->lock will be unlocked twice, fix it.
- Coding style fix.
- Add some comments.

v5:
- Make some function parameters const
- Call "spin_unlock_irq(&desc->lock);" a little eariler
- Add "ASSERT(spin_is_locked(&pcidevs_lock))"
- -EBADSLT -> -ENODEV, EBADSLT is removed in the lasted Xen

v4:
- Don't inline setup_posted_irte()
- const struct pi_desc *pi_desc for setup_posted_irte()
- return -EINVAL when pirq_spin_lock_irq_desc() fails.
- Make some variables const
- Release irq desc lock earlier in pi_update_irte()
- Remove the pointless do-while() loop when doing cmpxchg16b()

v3:
- Remove "adding PDA_MASK()" when updating 'pda_l' and 'pda_h' for IRTE.
- Change the return type of pi_update_irte() to int.
- Remove some pointless printk message in pi_update_irte().
- Use structure assignment instead of memcpy() for irte copy.

 xen/drivers/passthrough/vtd/intremap.c | 120 +++++++++++++++++++++++++++++++++
 xen/drivers/passthrough/vtd/iommu.h    |   6 ++
 xen/include/asm-x86/iommu.h            |   2 +
 3 files changed, 128 insertions(+)

diff --git a/xen/drivers/passthrough/vtd/intremap.c 
b/xen/drivers/passthrough/vtd/intremap.c
index 8f135e1..67e4f6d 100644
--- a/xen/drivers/passthrough/vtd/intremap.c
+++ b/xen/drivers/passthrough/vtd/intremap.c
@@ -899,3 +899,123 @@ void iommu_disable_x2apic_IR(void)
     for_each_drhd_unit ( drhd )
         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, sizeof(*new_ire), 0);
+
+    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.
+ */
+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;
+
+    desc = pirq_spin_lock_irq_desc(pirq, NULL);
+    if ( !desc )
+        return -EINVAL;
+
+    msi_desc = desc->msi_desc;
+    if ( !msi_desc )
+    {
+        rc = -ENODEV;
+        goto unlock_out;
+    }
+
+    pci_dev = msi_desc->dev;
+    if ( !pci_dev )
+    {
+        rc = -ENODEV;
+        goto unlock_out;
+    }
+
+    remap_index = msi_desc->remap_index;
+
+    spin_unlock_irq(&desc->lock);
+
+    ASSERT(spin_is_locked(&pcidevs_lock));
+
+    /*
+     * 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;
+
+ unlock_out:
+    spin_unlock_irq(&desc->lock);
+
+    return rc;
+}
diff --git a/xen/drivers/passthrough/vtd/iommu.h 
b/xen/drivers/passthrough/vtd/iommu.h
index b440b69..c55ee08 100644
--- a/xen/drivers/passthrough/vtd/iommu.h
+++ b/xen/drivers/passthrough/vtd/iommu.h
@@ -323,6 +323,12 @@ struct iremap_entry {
   };
 };
 
+/*
+ * Posted-interrupt descriptor address is 64 bits with 64-byte aligned, only
+ * the upper 26 bits of lest significiant 32 bits is available.
+ */
+#define PDA_LOW_BIT    26
+
 /* Max intr remapping table page order is 8, as max number of IRTEs is 64K */
 #define IREMAP_PAGE_ORDER  8
 
diff --git a/xen/include/asm-x86/iommu.h b/xen/include/asm-x86/iommu.h
index 29203d7..92f0900 100644
--- a/xen/include/asm-x86/iommu.h
+++ b/xen/include/asm-x86/iommu.h
@@ -31,6 +31,8 @@ int iommu_supports_eim(void);
 int iommu_enable_x2apic_IR(void);
 void iommu_disable_x2apic_IR(void);
 
+int pi_update_irte(const struct vcpu *v, const struct pirq *pirq, const 
uint8_t gvec);
+
 #endif /* !__ARCH_X86_IOMMU_H__ */
 /*
  * Local variables:
-- 
2.1.0


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