From: Matthew Rosato <mjros...@linux.ibm.com> Currently, s390x-pci performs accounting against the vfio DMA limit and triggers the guest to clean up mappings when the limit is reached. Let's go a step further and also limit the size of the supported DMA aperture reported to the guest based upon the initial vfio DMA limit reported for the container (if less than than the size reported by the firmware/host zPCI layer). This avoids processing sections of the guest DMA table during global refresh that, for common use cases, will never be used anway, and makes exhausting the vfio DMA limit due to mismatch between guest aperture size and host limit far less likely and more indicitive of an error.
Signed-off-by: Matthew Rosato <mjros...@linux.ibm.com> Message-Id: <20221028194758.204007-4-mjros...@linux.ibm.com> Reviewed-by: Eric Farman <far...@linux.ibm.com> Signed-off-by: Thomas Huth <th...@redhat.com> --- include/hw/s390x/s390-pci-bus.h | 1 + hw/s390x/s390-pci-vfio.c | 11 +++++++++++ 2 files changed, 12 insertions(+) diff --git a/include/hw/s390x/s390-pci-bus.h b/include/hw/s390x/s390-pci-bus.h index 0605fcea24..1c46e3a269 100644 --- a/include/hw/s390x/s390-pci-bus.h +++ b/include/hw/s390x/s390-pci-bus.h @@ -278,6 +278,7 @@ struct S390PCIIOMMU { uint64_t g_iota; uint64_t pba; uint64_t pal; + uint64_t max_dma_limit; GHashTable *iotlb; S390PCIDMACount *dma_limit; }; diff --git a/hw/s390x/s390-pci-vfio.c b/hw/s390x/s390-pci-vfio.c index 5f0adb0b4a..f7bf36cec8 100644 --- a/hw/s390x/s390-pci-vfio.c +++ b/hw/s390x/s390-pci-vfio.c @@ -84,6 +84,7 @@ S390PCIDMACount *s390_pci_start_dma_count(S390pciState *s, cnt->users = 1; cnt->avail = avail; QTAILQ_INSERT_TAIL(&s->zpci_dma_limit, cnt, link); + pbdev->iommu->max_dma_limit = avail; return cnt; } @@ -103,6 +104,7 @@ static void s390_pci_read_base(S390PCIBusDevice *pbdev, struct vfio_info_cap_header *hdr; struct vfio_device_info_cap_zpci_base *cap; VFIOPCIDevice *vpci = container_of(pbdev->pdev, VFIOPCIDevice, pdev); + uint64_t vfio_size; hdr = vfio_get_device_info_cap(info, VFIO_DEVICE_INFO_CAP_ZPCI_BASE); @@ -122,6 +124,15 @@ static void s390_pci_read_base(S390PCIBusDevice *pbdev, /* The following values remain 0 until we support other FMB formats */ pbdev->zpci_fn.fmbl = 0; pbdev->zpci_fn.pft = 0; + + /* + * If appropriate, reduce the size of the supported DMA aperture reported + * to the guest based upon the vfio DMA limit. + */ + vfio_size = pbdev->iommu->max_dma_limit << TARGET_PAGE_BITS; + if (vfio_size < (cap->end_dma - cap->start_dma + 1)) { + pbdev->zpci_fn.edma = cap->start_dma + vfio_size - 1; + } } static bool get_host_fh(S390PCIBusDevice *pbdev, struct vfio_device_info *info, -- 2.31.1