From: Matthew Rosato <mjrosato@xxxxxxxxxxxxx>
The fix in dbe9cf606c shrinks the IOMMU memory region to a size
that seems reasonable on the surface, however is actually too
small as it is based against a 0-mapped address space. This
causes breakage with small guests as they can overrun the IOMMU window.
Let's go back to the prior method of initializing iommu for now.
Fixes: dbe9cf606c ("s390x/pci: Set the iommu region size mpcifc request")
Cc: qemu-stable@xxxxxxxxxx
Reviewed-by: Pierre Morel <pmorel@xxxxxxxxxxxxx>
Reported-by: Boris Fiuczynski <fiuczy@xxxxxxxxxxxxx>
Tested-by: Boris Fiuczynski <fiuczy@xxxxxxxxxxxxx>
Reported-by: Stefan Zimmerman <stzi@xxxxxxxxxxxxx>
Signed-off-by: Matthew Rosato <mjrosato@xxxxxxxxxxxxx>
Message-Id: <1569507036-15314-1-git-send-email-mjrosato@xxxxxxxxxxxxx>
Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
---
hw/s390x/s390-pci-bus.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/hw/s390x/s390-pci-bus.c b/hw/s390x/s390-pci-bus.c
index 963a41c7f532..2d2f4a7c419c 100644
--- a/hw/s390x/s390-pci-bus.c
+++ b/hw/s390x/s390-pci-bus.c
@@ -695,10 +695,15 @@ static const MemoryRegionOps s390_msi_ctrl_ops = {
void s390_pci_iommu_enable(S390PCIIOMMU *iommu)
{
+ /*
+ * The iommu region is initialized against a 0-mapped address space,
+ * so the smallest IOMMU region we can define runs from 0 to the end
+ * of the PCI address space.
+ */
char *name = g_strdup_printf("iommu-s390-%04x", iommu->pbdev->uid);
memory_region_init_iommu(&iommu->iommu_mr, sizeof(iommu->iommu_mr),
TYPE_S390_IOMMU_MEMORY_REGION, OBJECT(&iommu->mr),
- name, iommu->pal - iommu->pba + 1);
+ name, iommu->pal + 1);
iommu->enabled = true;
memory_region_add_subregion(&iommu->mr, 0, MEMORY_REGION(&iommu->iommu_mr));
g_free(name);
--
2.21.0
