On 2016/3/17 0:32, Alex Williamson wrote:

On Mon,  7 Mar 2016 15:48:38 +0800
Yongji Xie [off-list ref] wrote:

quoted

This patch adds IOMMU_CAP_INTR_REMAP for IODA host bridge so that
we can mmap MSI-X table in vfio driver.

Signed-off-by: Yongji Xie <redacted>
---
  arch/powerpc/platforms/powernv/pci-ioda.c |   17 +++++++++++++++++
  1 file changed, 17 insertions(+)

diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
index f90dc04..f01b9ab 100644
--- a/arch/powerpc/platforms/powernv/pci-ioda.c
+++ b/arch/powerpc/platforms/powernv/pci-ioda.c

@@ -1955,6 +1955,20 @@ static struct iommu_table_ops pnv_ioda2_iommu_ops = {
  	.free = pnv_ioda2_table_free,
  };
  
+static bool pnv_ioda_iommu_capable(enum iommu_cap cap)
+{
+	switch (cap) {
+	case IOMMU_CAP_INTR_REMAP:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static struct iommu_ops pnv_ioda_iommu_ops = {
+	.capable = pnv_ioda_iommu_capable,
+};
+
  static void pnv_pci_ioda_setup_dma_pe(struct pnv_phb *phb,
  				      struct pnv_ioda_pe *pe, unsigned int base,
  				      unsigned int segs)

@@ -3078,6 +3092,9 @@ static void pnv_pci_ioda_fixup(void)
  
  	/* Link NPU IODA tables to their PCI devices. */
  	pnv_npu_ioda_fixup();
+
+	/* Add IOMMU_CAP_INTR_REMAP */
+	bus_set_iommu(&pci_bus_type, &pnv_ioda_iommu_ops);
  }
  
  /*

Doesn't this set you up for a world of hurt?  bus_set_iommu() calls
iommu_bus_init() which sets up notifiers, which maybe you don't care
about, but it also means that iommu_domain_alloc(&pci_bus_type) will
segfault because you're not providing a domain_alloc callback here.

It seems to be hard to add IOMMU_CAP_INTR_REMAP on
PPC64 platform.

And can we add a new ioctl in vfio_iommu_driver to check
if interrupt remapping is supported so that we can use our
own way to determine that on PPC64 platform?

Thanks,
Yongji Xie