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Blame SOURCES/kvm-intel-iommu-only-do-page-walk-for-MAP-notifiers.patch

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From 3ce00f8e07a2f9e1b3839b367821121511301c9f Mon Sep 17 00:00:00 2001
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From: Peter Xu <peterx@redhat.com>
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Date: Fri, 12 Oct 2018 07:58:41 +0100
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Subject: [PATCH 11/17] intel-iommu: only do page walk for MAP notifiers
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RH-Author: Peter Xu <peterx@redhat.com>
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Message-id: <20181012075846.25449-5-peterx@redhat.com>
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Patchwork-id: 82677
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O-Subject: [RHEL-8 qemu-kvm PATCH 4/9] intel-iommu: only do page walk for MAP notifiers
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Bugzilla: 1450712
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RH-Acked-by: Auger Eric <eric.auger@redhat.com>
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RH-Acked-by: Xiao Wang <jasowang@redhat.com>
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RH-Acked-by: Michael S. Tsirkin <mst@redhat.com>
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For UNMAP-only IOMMU notifiers, we don't need to walk the page tables.
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Fasten that procedure by skipping the page table walk.  That should
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boost performance for UNMAP-only notifiers like vhost.
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CC: QEMU Stable <qemu-stable@nongnu.org>
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Signed-off-by: Peter Xu <peterx@redhat.com>
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Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
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Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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(cherry picked from commit 4f8a62a933a79094e44bc1b16b63bb23e62d67b4)
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Signed-off-by: Peter Xu <peterx@redhat.com>
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Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
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---
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 hw/i386/intel_iommu.c         | 44 ++++++++++++++++++++++++++++++++++++++-----
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 include/hw/i386/intel_iommu.h |  2 ++
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 2 files changed, 41 insertions(+), 5 deletions(-)
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diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
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index 8d4069d..38ccc74 100644
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--- a/hw/i386/intel_iommu.c
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+++ b/hw/i386/intel_iommu.c
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@@ -138,6 +138,12 @@ static inline void vtd_iommu_unlock(IntelIOMMUState *s)
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     qemu_mutex_unlock(&s->iommu_lock);
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 }
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+/* Whether the address space needs to notify new mappings */
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+static inline gboolean vtd_as_has_map_notifier(VTDAddressSpace *as)
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+{
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+    return as->notifier_flags & IOMMU_NOTIFIER_MAP;
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+}
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+
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 /* GHashTable functions */
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 static gboolean vtd_uint64_equal(gconstpointer v1, gconstpointer v2)
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 {
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@@ -1436,14 +1442,36 @@ static void vtd_iotlb_page_invalidate_notify(IntelIOMMUState *s,
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     VTDAddressSpace *vtd_as;
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     VTDContextEntry ce;
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     int ret;
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+    hwaddr size = (1 << am) * VTD_PAGE_SIZE;
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     QLIST_FOREACH(vtd_as, &(s->vtd_as_with_notifiers), next) {
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         ret = vtd_dev_to_context_entry(s, pci_bus_num(vtd_as->bus),
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                                        vtd_as->devfn, &ce);
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         if (!ret && domain_id == VTD_CONTEXT_ENTRY_DID(ce.hi)) {
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-            vtd_page_walk(&ce, addr, addr + (1 << am) * VTD_PAGE_SIZE,
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-                          vtd_page_invalidate_notify_hook,
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-                          (void *)&vtd_as->iommu, true, s->aw_bits);
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+            if (vtd_as_has_map_notifier(vtd_as)) {
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+                /*
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+                 * As long as we have MAP notifications registered in
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+                 * any of our IOMMU notifiers, we need to sync the
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+                 * shadow page table.
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+                 */
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+                vtd_page_walk(&ce, addr, addr + size,
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+                              vtd_page_invalidate_notify_hook,
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+                              (void *)&vtd_as->iommu, true, s->aw_bits);
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+            } else {
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+                /*
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+                 * For UNMAP-only notifiers, we don't need to walk the
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+                 * page tables.  We just deliver the PSI down to
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+                 * invalidate caches.
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+                 */
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+                IOMMUTLBEntry entry = {
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+                    .target_as = &address_space_memory,
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+                    .iova = addr,
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+                    .translated_addr = 0,
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+                    .addr_mask = size - 1,
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+                    .perm = IOMMU_NONE,
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+                };
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+                memory_region_notify_iommu(&vtd_as->iommu, entry);
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+            }
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         }
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     }
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 }
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@@ -2383,6 +2411,9 @@ static void vtd_iommu_notify_flag_changed(IOMMUMemoryRegion *iommu,
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         exit(1);
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     }
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+    /* Update per-address-space notifier flags */
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+    vtd_as->notifier_flags = new;
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+
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     if (old == IOMMU_NOTIFIER_NONE) {
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         QLIST_INSERT_HEAD(&s->vtd_as_with_notifiers, vtd_as, next);
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     } else if (new == IOMMU_NOTIFIER_NONE) {
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@@ -2891,8 +2922,11 @@ static void vtd_iommu_replay(IOMMUMemoryRegion *iommu_mr, IOMMUNotifier *n)
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                                   PCI_FUNC(vtd_as->devfn),
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                                   VTD_CONTEXT_ENTRY_DID(ce.hi),
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                                   ce.hi, ce.lo);
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-        vtd_page_walk(&ce, 0, ~0ULL, vtd_replay_hook, (void *)n, false,
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-                      s->aw_bits);
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+        if (vtd_as_has_map_notifier(vtd_as)) {
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+            /* This is required only for MAP typed notifiers */
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+            vtd_page_walk(&ce, 0, ~0ULL, vtd_replay_hook, (void *)n, false,
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+                          s->aw_bits);
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+        }
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     } else {
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         trace_vtd_replay_ce_invalid(bus_n, PCI_SLOT(vtd_as->devfn),
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                                     PCI_FUNC(vtd_as->devfn));
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diff --git a/include/hw/i386/intel_iommu.h b/include/hw/i386/intel_iommu.h
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index 016e74b..156f35e 100644
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--- a/include/hw/i386/intel_iommu.h
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+++ b/include/hw/i386/intel_iommu.h
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@@ -93,6 +93,8 @@ struct VTDAddressSpace {
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     IntelIOMMUState *iommu_state;
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     VTDContextCacheEntry context_cache_entry;
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     QLIST_ENTRY(VTDAddressSpace) next;
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+    /* Superset of notifier flags that this address space has */
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+    IOMMUNotifierFlag notifier_flags;
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 };
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 struct VTDBus {
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-- 
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1.8.3.1
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