[PATCH v12 01/17] s390x/pci: implement IOMMU replay

[Konstantin Shkolnyy <kshk@linux.ibm.com>]

From: Matthew Rosato <mjrosato@linux.ibm.com>

There are a few scenarios where IOMMU replay can potentially be needed
for zPCI device, namely VFIO device reset scenarios where the guest
continues running and expects the contents of its IOMMU to be replayed
upon IOAT re-registration and migration scenarios where the destination
must reconstruct the IOMMU on the destination.

zPCI migration is not supported yet, but the IOMMU replay function is
implemented so that it can be called both from IOMMUMemoryRegionClass
now and migration post_load later.

Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
Signed-off-by: Konstantin Shkolnyy <kshk@linux.ibm.com>
Reviewed-by: Farhan Ali <alifm@linux.ibm.com>
---
 hw/s390x/s390-pci-bus.c          | 71 +++++++++++++++++++++++++++++---
 hw/s390x/s390-pci-inst.c         |  4 +-
 include/hw/s390x/s390-pci-inst.h |  1 +
 3 files changed, 69 insertions(+), 7 deletions(-)

diff --git a/hw/s390x/s390-pci-bus.c b/hw/s390x/s390-pci-bus.c
index 2eb4e8cec4..b3f7b59422 100644
--- a/hw/s390x/s390-pci-bus.c
+++ b/hw/s390x/s390-pci-bus.c
@@ -593,14 +593,75 @@ err:
     return ret;
 }
 
-static void s390_pci_iommu_replay(IOMMUMemoryRegion *iommu,
+static void s390_pci_ioat_replay(S390PCIIOMMU *iommu)
+{
+    S390PCIBusDevice *pbdev = iommu->pbdev;
+    S390IOTLBEntry entry;
+    uint16_t error = 0;
+    uint32_t dma_avail;
+    hwaddr curr, end;
+
+    curr = iommu->pba;
+    end = iommu->pal;
+
+    if (iommu->dm_mr || !pbdev) {
+        /* If direct mapping is used, there are no guest tables to replay */
+        return;
+    }
+
+    if (iommu->dma_limit) {
+        dma_avail = iommu->dma_limit->avail;
+    } else {
+        dma_avail = 1;
+    }
+
+    while (curr < end) {
+        error = s390_guest_io_table_walk(iommu->g_iota, curr, &entry);
+        if (error) {
+            pbdev->state = ZPCI_FS_ERROR;
+            s390_pci_generate_error_event(error, pbdev->fh, pbdev->fid, curr,
+                                          0);
+            error_report("Failure to walk table during iommu remap");
+            return;
+        }
+
+        /* Advance to next frame boundary if start was not frame-aligned */
+        curr = QEMU_ALIGN_UP(curr + 1, entry.len);
+        if (entry.perm != IOMMU_NONE) {
+            while (entry.iova < curr && entry.iova < end) {
+                if (dma_avail > 0) {
+                    dma_avail = s390_pci_update_iotlb(iommu, &entry);
+                } else {
+                    /*
+                     * There is no reliable method to request the guest to
+                     * release mappings other than in response to a RPCIT
+                     * instruction; generate a permanent error condition and
+                     * require the device to be completely re-initialized from
+                     * the guest side.
+                     */
+                    pbdev->state = ZPCI_FS_ERROR;
+                    s390_pci_generate_error_event(ERR_EVENT_PERMERR, pbdev->fh,
+                                                  pbdev->fid, 0, 0);
+                    error_report("DMA mappings exhausted: iommu remap failed");
+                    return;
+                }
+                entry.iova += TARGET_PAGE_SIZE;
+                entry.translated_addr += TARGET_PAGE_SIZE;
+            }
+        }
+    }
+}
+
+static void s390_pci_iommu_replay(IOMMUMemoryRegion *mr,
                                   IOMMUNotifier *notifier)
 {
-    /* It's impossible to plug a pci device on s390x that already has iommu
-     * mappings which need to be replayed, that is due to the "one iommu per
-     * zpci device" construct. But when we support migration of vfio-pci
-     * devices in future, we need to revisit this.
+    S390PCIIOMMU *iommu = container_of(mr, S390PCIIOMMU, iommu_mr);
+
+    /*
+     * The notifier argument is not used directly; s390_pci_ioat_replay()
+     * broadcasts via memory_region_notify_iommu() instead.
      */
+    s390_pci_ioat_replay(iommu);
 }
 
 static S390PCIIOMMU *s390_pci_get_iommu(S390pciState *s, PCIBus *bus,
diff --git a/hw/s390x/s390-pci-inst.c b/hw/s390x/s390-pci-inst.c
index 09026360d4..285ff0e089 100644
--- a/hw/s390x/s390-pci-inst.c
+++ b/hw/s390x/s390-pci-inst.c
@@ -630,8 +630,8 @@ int pcistg_service_call(S390CPU *cpu, uint8_t r1, uint8_t r2, uintptr_t ra)
     return 0;
 }
 
-static uint32_t s390_pci_update_iotlb(S390PCIIOMMU *iommu,
-                                      S390IOTLBEntry *entry)
+uint32_t s390_pci_update_iotlb(S390PCIIOMMU *iommu,
+                               S390IOTLBEntry *entry)
 {
     S390IOTLBEntry *cache = g_hash_table_lookup(iommu->iotlb, &entry->iova);
     IOMMUTLBEvent event = {
diff --git a/include/hw/s390x/s390-pci-inst.h b/include/hw/s390x/s390-pci-inst.h
index 5cb8da540b..c782990e3b 100644
--- a/include/hw/s390x/s390-pci-inst.h
+++ b/include/hw/s390x/s390-pci-inst.h
@@ -111,6 +111,7 @@ int mpcifc_service_call(S390CPU *cpu, uint8_t r1, uint64_t fiba, uint8_t ar,
 int stpcifc_service_call(S390CPU *cpu, uint8_t r1, uint64_t fiba, uint8_t ar,
                          uintptr_t ra);
 void fmb_timer_free(S390PCIBusDevice *pbdev);
+uint32_t s390_pci_update_iotlb(S390PCIIOMMU *iommu, S390IOTLBEntry *entry);
 
 #define ZPCI_IO_BAR_MIN 0
 #define ZPCI_IO_BAR_MAX 5
-- 
2.34.1