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Re: [Xen-devel] [v3][PATCH 04/16] xen/passthrough: extend hypercall to support rdm reservation policy



On 2015/6/11 17:28, Tian, Kevin wrote:
From: Chen, Tiejun
Sent: Thursday, June 11, 2015 9:15 AM

This patch extends the existing hypercall to support rdm reservation policy.
We return error or just throw out a warning message depending on whether
the policy is "strict" or "relaxed" when reserving RDM regions in pfn space.
Note in some special cases, e.g. add a device to hwdomain, and remove a
device from user domain, 'relaxed' is fine enough since this is always safe
to hwdomain.

could you elaborate " add a device to hwdomain, and remove a device
from user domain "? move a device from user domain to hwdomain
or completely irrelevant?

Yes, they're not relevant. And I think we shouldn't care our policy,

#1. When add a device to hwdomain

I think RMRR is always reserved on e820 so either of flag is fine.

#2. remove a device from domain

"remove" action also can ignore that since the original mechanism is enough.



Signed-off-by: Tiejun Chen <tiejun.chen@xxxxxxxxx>
---
  xen/arch/x86/mm/p2m.c                       |  8 +++++++-
  xen/drivers/passthrough/amd/pci_amd_iommu.c |  3 ++-
  xen/drivers/passthrough/arm/smmu.c          |  2 +-
  xen/drivers/passthrough/device_tree.c       | 11 ++++++++++-
  xen/drivers/passthrough/pci.c               | 10 ++++++----
  xen/drivers/passthrough/vtd/iommu.c         | 20 ++++++++++++--------
  xen/include/asm-x86/p2m.h                   |  2 +-
  xen/include/public/domctl.h                 |  5 +++++
  xen/include/xen/iommu.h                     |  2 +-
  9 files changed, 45 insertions(+), 18 deletions(-)

diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
index c7198a5..3fcdcac 100644
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -899,7 +899,7 @@ int set_mmio_p2m_entry(struct domain *d, unsigned long gfn,
mfn_t mfn,
  }

  int set_identity_p2m_entry(struct domain *d, unsigned long gfn,
-                           p2m_access_t p2ma)
+                           p2m_access_t p2ma, u32 flag)
  {
      p2m_type_t p2mt;
      p2m_access_t a;
@@ -924,6 +924,12 @@ int set_identity_p2m_entry(struct domain *d, unsigned long 
gfn,
              printk(XENLOG_G_WARNING
                     "Cannot identity map d%d:%lx, already mapped to %lx.\n",
                     d->domain_id, gfn, mfn_x(mfn));
+
+            if ( flag == XEN_DOMCTL_DEV_RDM_RELAXED )
+            {
+                ret = 0;
+                printk(XENLOG_G_WARNING "Some devices may work failed.\n");

Do you need this extra printk? The warning message is already given
several lines above and here you just need to change return value
for relaxed policy.

Okay.


+            }
          }

          gfn_unlock(p2m, gfn, 0);
diff --git a/xen/drivers/passthrough/amd/pci_amd_iommu.c
b/xen/drivers/passthrough/amd/pci_amd_iommu.c
index e83bb35..920b35a 100644
--- a/xen/drivers/passthrough/amd/pci_amd_iommu.c
+++ b/xen/drivers/passthrough/amd/pci_amd_iommu.c
@@ -394,7 +394,8 @@ static int reassign_device(struct domain *source, struct 
domain
*target,
  }

  static int amd_iommu_assign_device(struct domain *d, u8 devfn,
-                                   struct pci_dev *pdev)
+                                   struct pci_dev *pdev,
+                                   u32 flag)
  {
      struct ivrs_mappings *ivrs_mappings = get_ivrs_mappings(pdev->seg);
      int bdf = PCI_BDF2(pdev->bus, devfn);
diff --git a/xen/drivers/passthrough/arm/smmu.c
b/xen/drivers/passthrough/arm/smmu.c
index 6cc4394..9a667e9 100644
--- a/xen/drivers/passthrough/arm/smmu.c
+++ b/xen/drivers/passthrough/arm/smmu.c
@@ -2605,7 +2605,7 @@ static void arm_smmu_destroy_iommu_domain(struct
iommu_domain *domain)
  }

  static int arm_smmu_assign_dev(struct domain *d, u8 devfn,
-                              struct device *dev)
+                              struct device *dev, u32 flag)
  {
        struct iommu_domain *domain;
        struct arm_smmu_xen_domain *xen_domain;
diff --git a/xen/drivers/passthrough/device_tree.c
b/xen/drivers/passthrough/device_tree.c
index 5d3842a..ea85645 100644
--- a/xen/drivers/passthrough/device_tree.c
+++ b/xen/drivers/passthrough/device_tree.c
@@ -52,7 +52,8 @@ int iommu_assign_dt_device(struct domain *d, struct
dt_device_node *dev)
              goto fail;
      }

-    rc = hd->platform_ops->assign_device(d, 0, dt_to_dev(dev));
+    rc = hd->platform_ops->assign_device(d, 0, dt_to_dev(dev),
+                                         XEN_DOMCTL_DEV_NO_RDM);

      if ( rc )
          goto fail;
@@ -148,6 +149,14 @@ int iommu_do_dt_domctl(struct xen_domctl *domctl, struct
domain *d,
          if ( domctl->u.assign_device.dev != XEN_DOMCTL_DEV_DT )
              break;

+        if ( domctl->u.assign_device.flag == XEN_DOMCTL_DEV_NO_RDM )
+        {
+            printk(XENLOG_G_ERR "XEN_DOMCTL_assign_device: assign \"%s\""
+                   " to dom%u failed (%d) since we don't support RDM.\n",
+                   dt_node_full_name(dev), d->domain_id, ret);
+            break;
+        }
+
          if ( unlikely(d->is_dying) )
          {
              ret = -EINVAL;
diff --git a/xen/drivers/passthrough/pci.c b/xen/drivers/passthrough/pci.c
index e30be43..557c87e 100644
--- a/xen/drivers/passthrough/pci.c
+++ b/xen/drivers/passthrough/pci.c
@@ -1335,7 +1335,7 @@ static int device_assigned(u16 seg, u8 bus, u8 devfn)
      return pdev ? 0 : -EBUSY;
  }

-static int assign_device(struct domain *d, u16 seg, u8 bus, u8 devfn)
+static int assign_device(struct domain *d, u16 seg, u8 bus, u8 devfn, u32 flag)
  {
      struct hvm_iommu *hd = domain_hvm_iommu(d);
      struct pci_dev *pdev;
@@ -1371,7 +1371,7 @@ static int assign_device(struct domain *d, u16 seg, u8 
bus, u8
devfn)

      pdev->fault.count = 0;

-    if ( (rc = hd->platform_ops->assign_device(d, devfn, pci_to_dev(pdev))) )
+    if ( (rc = hd->platform_ops->assign_device(d, devfn, pci_to_dev(pdev), 
flag)) )
          goto done;

      for ( ; pdev->phantom_stride; rc = 0 )
@@ -1379,7 +1379,7 @@ static int assign_device(struct domain *d, u16 seg, u8 
bus, u8
devfn)
          devfn += pdev->phantom_stride;
          if ( PCI_SLOT(devfn) != PCI_SLOT(pdev->devfn) )
              break;
-        rc = hd->platform_ops->assign_device(d, devfn, pci_to_dev(pdev));
+        rc = hd->platform_ops->assign_device(d, devfn, pci_to_dev(pdev), flag);
          if ( rc )
              printk(XENLOG_G_WARNING "d%d: assign %04x:%02x:%02x.%u failed
(%d)\n",
                     d->domain_id, seg, bus, PCI_SLOT(devfn), PCI_FUNC(devfn),
@@ -1496,6 +1496,7 @@ int iommu_do_pci_domctl(
  {
      u16 seg;
      u8 bus, devfn;
+    u32 flag;
      int ret = 0;
      uint32_t machine_sbdf;

@@ -1577,9 +1578,10 @@ int iommu_do_pci_domctl(
          seg = machine_sbdf >> 16;
          bus = PCI_BUS(machine_sbdf);
          devfn = PCI_DEVFN2(machine_sbdf);
+        flag = domctl->u.assign_device.flag;

          ret = device_assigned(seg, bus, devfn) ?:
-              assign_device(d, seg, bus, devfn);
+              assign_device(d, seg, bus, devfn, flag);
          if ( ret == -ERESTART )
              ret = hypercall_create_continuation(__HYPERVISOR_domctl,
                                                  "h", u_domctl);
diff --git a/xen/drivers/passthrough/vtd/iommu.c
b/xen/drivers/passthrough/vtd/iommu.c
index 31ce1af..d7c9e1c 100644
--- a/xen/drivers/passthrough/vtd/iommu.c
+++ b/xen/drivers/passthrough/vtd/iommu.c
@@ -1808,7 +1808,8 @@ static void iommu_set_pgd(struct domain *d)
  }

  static int rmrr_identity_mapping(struct domain *d, bool_t map,
-                                 const struct acpi_rmrr_unit *rmrr)
+                                 const struct acpi_rmrr_unit *rmrr,
+                                 u32 flag)
  {
      unsigned long base_pfn = rmrr->base_address >> PAGE_SHIFT_4K;
      unsigned long end_pfn = PAGE_ALIGN_4K(rmrr->end_address) >>
PAGE_SHIFT_4K;
@@ -1856,7 +1857,7 @@ static int rmrr_identity_mapping(struct domain *d, bool_t 
map,

      while ( base_pfn < end_pfn )
      {
-        int err = set_identity_p2m_entry(d, base_pfn, p2m_access_rw);
+        int err = set_identity_p2m_entry(d, base_pfn, p2m_access_rw, flag);

          if ( err )
              return err;
@@ -1899,7 +1900,8 @@ static int intel_iommu_add_device(u8 devfn, struct pci_dev
*pdev)
               PCI_BUS(bdf) == pdev->bus &&
               PCI_DEVFN2(bdf) == devfn )
          {
-            ret = rmrr_identity_mapping(pdev->domain, 1, rmrr);
+            ret = rmrr_identity_mapping(pdev->domain, 1, rmrr,
+                                        XEN_DOMCTL_DEV_RDM_RELAXED);

Why did you hardcode relax policy here? Shouldn't the policy come
from hypercall flag?

I just saw we have one path to use intel_iommu_add_device(),

pci_add_device()
    |
    + if ( !pdev->domain )
      {
        pdev->domain = hardware_domain;
        ret = iommu_add_device(pdev);
            |
            + hd->platform_ops->add_device()
                |
                + intel_iommu_add_device()

So I think intel_iommu_add_device() is used to add a device to hardware_domain. And in our case hardware_domain should be special as I explained above.


              if ( ret )
                  dprintk(XENLOG_ERR VTDPREFIX, "d%d: RMRR mapping failed\n",
                          pdev->domain->domain_id);
@@ -1940,7 +1942,8 @@ static int intel_iommu_remove_device(u8 devfn, struct 
pci_dev
*pdev)
               PCI_DEVFN2(bdf) != devfn )
              continue;

-        rmrr_identity_mapping(pdev->domain, 0, rmrr);
+        rmrr_identity_mapping(pdev->domain, 0, rmrr,
+                              XEN_DOMCTL_DEV_RDM_RELAXED);

ditto

It doesn't matter when we're trying to remove a device since we don't care this flag.


      }

      return domain_context_unmap(pdev->domain, devfn, pdev);
@@ -2098,7 +2101,7 @@ static void __hwdom_init setup_hwdom_rmrr(struct domain 
*d)
      spin_lock(&pcidevs_lock);
      for_each_rmrr_device ( rmrr, bdf, i )
      {
-        ret = rmrr_identity_mapping(d, 1, rmrr);
+        ret = rmrr_identity_mapping(d, 1, rmrr, XEN_DOMCTL_DEV_RDM_RELAXED);
          if ( ret )
              dprintk(XENLOG_ERR VTDPREFIX,
                       "IOMMU: mapping reserved region failed\n");
@@ -2241,7 +2244,8 @@ static int reassign_device_ownership(
                   PCI_BUS(bdf) == pdev->bus &&
                   PCI_DEVFN2(bdf) == devfn )
              {
-                ret = rmrr_identity_mapping(source, 0, rmrr);
+                ret = rmrr_identity_mapping(source, 0, rmrr,
+                                            XEN_DOMCTL_DEV_RDM_RELAXED);
                  if ( ret != -ENOENT )
                      return ret;
              }
@@ -2265,7 +2269,7 @@ static int reassign_device_ownership(
  }

  static int intel_iommu_assign_device(
-    struct domain *d, u8 devfn, struct pci_dev *pdev)
+    struct domain *d, u8 devfn, struct pci_dev *pdev, u32 flag)
  {
      struct acpi_rmrr_unit *rmrr;
      int ret = 0, i;
@@ -2294,7 +2298,7 @@ static int intel_iommu_assign_device(
               PCI_BUS(bdf) == bus &&
               PCI_DEVFN2(bdf) == devfn )
          {
-            ret = rmrr_identity_mapping(d, 1, rmrr);
+            ret = rmrr_identity_mapping(d, 1, rmrr, flag);
              if ( ret )
              {
                  reassign_device_ownership(d, hardware_domain, devfn, pdev);
diff --git a/xen/include/asm-x86/p2m.h b/xen/include/asm-x86/p2m.h
index 95b6266..a80b4f8 100644
--- a/xen/include/asm-x86/p2m.h
+++ b/xen/include/asm-x86/p2m.h
@@ -545,7 +545,7 @@ int clear_mmio_p2m_entry(struct domain *d, unsigned long 
gfn,
mfn_t mfn);

  /* Set identity addresses in the p2m table (for pass-through) */
  int set_identity_p2m_entry(struct domain *d, unsigned long gfn,
-                           p2m_access_t p2ma);
+                           p2m_access_t p2ma, u32 flag);

  /* Add foreign mapping to the guest's p2m table. */
  int p2m_add_foreign(struct domain *tdom, unsigned long fgfn,
diff --git a/xen/include/public/domctl.h b/xen/include/public/domctl.h
index bc45ea5..2f9e40e 100644
--- a/xen/include/public/domctl.h
+++ b/xen/include/public/domctl.h
@@ -478,6 +478,11 @@ struct xen_domctl_assign_device {
              XEN_GUEST_HANDLE_64(char) path; /* path to the device tree node */
          } dt;
      } u;
+    /* IN */
+#define XEN_DOMCTL_DEV_NO_RDM           0
+#define XEN_DOMCTL_DEV_RDM_RELAXED      1
+#define XEN_DOMCTL_DEV_RDM_STRICT       2

I don't understand why we require a NO_RDM flag. Whether there
is RDM associated with a given device, it's reported by system
BIOS or through cmdline extension in coming patch. Why do we
require the hypercall to ask NO_RDM to hypervisor? The only flags
we want to pass to hypervisor is relaxed/strict policy, so hypervisor
know whether to fail or warn upon caught conflicts of identity
mapping...


This is just introduced to ARM as we discussed previously since we're touching some common interfaces.

Thanks
Tiejun

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