On 14.09.13 at 01:30, <suravee.suthikulpanit@amd.com> wrote:

From: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>

The current logic does not handle the case when HPET special->handle
is invalid in IVRS. On such system, the following message is shown:

(XEN) AMD-Vi: Failed to setup HPET MSI remapping: Wrong HPET

This patch will allow the ivrs_hpet[<handle>]=<sbdf> to override the
IVRS.

Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
---
 xen/drivers/passthrough/amd/iommu_acpi.c | 22 +++++++++++++++-------
 1 file changed, 15 insertions(+), 7 deletions(-)

diff --git a/xen/drivers/passthrough/amd/iommu_acpi.c 
b/xen/drivers/passthrough/amd/iommu_acpi.c
index 0778af0..bfcc2eb 100644
--- a/xen/drivers/passthrough/amd/iommu_acpi.c
+++ b/xen/drivers/passthrough/amd/iommu_acpi.c
@@ -671,6 +671,7 @@ static void __init parse_ivrs_hpet(char *str)
     if ( !s || *s )
         return;
 
+    hpet_sbdf.id = id;
     hpet_sbdf.bdf = PCI_BDF(bus, dev, func);
     hpet_sbdf.seg = seg;
     hpet_sbdf.cmdline = 1;
@@ -787,19 +788,26 @@ static u16 __init parse_ivhd_device_special(
         }
         break;
     case ACPI_IVHD_HPET:
+        if ( hpet_sbdf.cmdline )
+        {
+            AMD_IOMMU_DEBUG("IVHD: Command line override present for HPET %#x "
+                            "(IVRS: %#x devID %04x:%02x:%02x.%u)\n",
+                            hpet_sbdf.id, special->handle, seg, PCI_BUS(bdf),
+                            PCI_SLOT(bdf), PCI_FUNC(bdf));
+            hpet_sbdf.iommu = iommu;

This (unconditional) assignment is what the earlier logic attempted
to avoid: We must not blindly set this (and in particular not blindly
overwrite a previously set valid value), and in order to do so we
need to know whether to trust devid or handle. I'm therefore going
to apply only the first hunk - being a clear and obvious bug fix - for
the time being.

Jan