File s390x-pci-shrink-DMA-aperture-to-be-boun.patch of Package qemu

From: Matthew Rosato <mjrosato@linux.ibm.com>
Date: Fri, 28 Oct 2022 15:47:58 -0400
Subject: s390x/pci: shrink DMA aperture to be bound by vfio DMA limit

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 <mjrosato@linux.ibm.com>
Message-Id: <20221028194758.204007-4-mjrosato@linux.ibm.com>
Reviewed-by: Eric Farman <farman@linux.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
(cherry picked from commit df202e3ff3fccb49868e08f20d0bda86cb953fbe)
Resolves: bsc#1209064
Signed-off-by: Dario Faggioli <dfaggioli@suse.com>
---
 hw/s390x/s390-pci-vfio.c        | 11 +++++++++++
 include/hw/s390x/s390-pci-bus.h |  1 +
 2 files changed, 12 insertions(+)

diff --git a/hw/s390x/s390-pci-vfio.c b/hw/s390x/s390-pci-vfio.c
index 2aefa508a07d9a228c045a5ff50b..99806e2a846d260e2932fdecef07 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,
diff --git a/include/hw/s390x/s390-pci-bus.h b/include/hw/s390x/s390-pci-bus.h
index 0605fcea24d313693e1b1a0491c8..1c46e3a2691c93abc1d89f9b89df 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;
 };