[Xen-changelog] [xen master] libxl: disallow PCI device assignment for HVM guest when PoD is enabled

[patchbot@xxxxxxx]

commit c63868ff0164fa1927b0d39f9aef5c7074ee04e2
Author:     Wei Liu <wei.liu2@xxxxxxxxxx>
AuthorDate: Mon Jan 13 11:52:28 2014 +0000
Commit:     Ian Campbell <ian.campbell@xxxxxxxxxx>
CommitDate: Wed Jan 15 13:20:24 2014 +0000

    libxl: disallow PCI device assignment for HVM guest when PoD is enabled
    
    This replicates a Xend behavior, see ec789523749 ("xend: Dis-allow
    device assignment if PoD is enabled.").
    
    This change is restricted to HVM guest, as only HVM is relevant in the
    counterpart in Xend. We're late in release cycle so the change should
    only do what's necessary. Probably we can revisit it if we need to do
    the same thing for PV guest in the future.
    
    Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>
    Cc: Ian Campbell <ian.campbell@xxxxxxxxxx>
    Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
---
 tools/libxl/libxl_create.c |   20 ++++++++++++++++++++
 1 files changed, 20 insertions(+), 0 deletions(-)

diff --git a/tools/libxl/libxl_create.c b/tools/libxl/libxl_create.c
index 543e0c8..a604cd8 100644
--- a/tools/libxl/libxl_create.c
+++ b/tools/libxl/libxl_create.c
@@ -707,6 +707,7 @@ static void initiate_domain_create(libxl__egc *egc,
     uint32_t domid;
     int i, ret;
     size_t last_devid = -1;
+    bool pod_enabled = false;
 
     /* convenience aliases */
     libxl_domain_config *const d_config = dcs->guest_config;
@@ -715,6 +716,25 @@ static void initiate_domain_create(libxl__egc *egc,
 
     domid = 0;
 
+    /* If target_memkb is smaller than max_memkb, the subsequent call
+     * to libxc when building HVM domain will enable PoD mode.
+     */
+    pod_enabled = (d_config->c_info.type == LIBXL_DOMAIN_TYPE_HVM) &&
+        (d_config->b_info.target_memkb < d_config->b_info.max_memkb);
+
+    /* We cannot have PoD and PCI device assignment at the same time
+     * for HVM guest. It was reported that IOMMU cannot work with PoD
+     * enabled because it needs to populated entire page table for
+     * guest. To stay on the safe side, we disable PCI device
+     * assignment when PoD is enabled.
+     */
+    if (d_config->c_info.type == LIBXL_DOMAIN_TYPE_HVM &&
+        d_config->num_pcidevs && pod_enabled) {
+        ret = ERROR_INVAL;
+        LOG(ERROR, "PCI device assignment for HVM guest failed due to PoD 
enabled");
+        goto error_out;
+    }
+
     ret = libxl__domain_create_info_setdefault(gc, &d_config->c_info);
     if (ret) goto error_out;
 
--
generated by git-patchbot for /home/xen/git/xen.git#master

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