dma: Introduce dma_aligned_pow2_mask()

Currently get_naturally_aligned_size() is used by the intel iommu
to compute the maximum invalidation range based on @size which is
a power of 2 while being aligned with the @start address and less
than the maximum range defined by @gaw.

This helper is also useful for other iommu devices (virtio-iommu,
SMMUv3) to make sure IOMMU UNMAP notifiers only are called with
power of 2 range sizes.

Let's move this latter into dma-helpers.c and rename it into
dma_aligned_pow2_mask(). Also rewrite the helper so that it
accomodates UINT64_MAX values for the size mask and max mask.
It now returns a mask instead of a size. Change the caller.

Signed-off-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Message-id: 20210309102742.30442-3-eric.auger@redhat.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 7 insertions, 23 deletions

diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
index 3206f37..6be8f32 100644
--- a/hw/i386/intel_iommu.c
+++ b/hw/i386/intel_iommu.c
@@ -35,6 +35,7 @@
 #include "hw/i386/x86-iommu.h"
 #include "hw/pci-host/q35.h"
 #include "sysemu/kvm.h"
+#include "sysemu/dma.h"
 #include "sysemu/sysemu.h"
 #include "hw/i386/apic_internal.h"
 #include "kvm/kvm_i386.h"
@@ -3455,24 +3456,6 @@ VTDAddressSpace *vtd_find_add_as(IntelIOMMUState *s, PCIBus *bus, int devfn)
     return vtd_dev_as;
 }
 
-static uint64_t get_naturally_aligned_size(uint64_t start,
-                                           uint64_t size, int gaw)
-{
-    uint64_t max_mask = 1ULL << gaw;
-    uint64_t alignment = start ? start & -start : max_mask;
-
-    alignment = MIN(alignment, max_mask);
-    size = MIN(size, max_mask);
-
-    if (alignment <= size) {
-        /* Increase the alignment of start */
-        return alignment;
-    } else {
-        /* Find the largest page mask from size */
-        return 1ULL << (63 - clz64(size));
-    }
-}
-
 /* Unmap the whole range in the notifier's scope. */
 static void vtd_address_space_unmap(VTDAddressSpace *as, IOMMUNotifier *n)
 {
@@ -3501,13 +3484,14 @@ static void vtd_address_space_unmap(VTDAddressSpace *as, IOMMUNotifier *n)
 
     while (remain >= VTD_PAGE_SIZE) {
         IOMMUTLBEvent event;
-        uint64_t mask = get_naturally_aligned_size(start, remain, s->aw_bits);
+        uint64_t mask = dma_aligned_pow2_mask(start, end, s->aw_bits);
+        uint64_t size = mask + 1;
 
-        assert(mask);
+        assert(size);
 
         event.type = IOMMU_NOTIFIER_UNMAP;
         event.entry.iova = start;
-        event.entry.addr_mask = mask - 1;
+        event.entry.addr_mask = mask;
         event.entry.target_as = &address_space_memory;
         event.entry.perm = IOMMU_NONE;
         /* This field is meaningless for unmap */
@@ -3515,8 +3499,8 @@ static void vtd_address_space_unmap(VTDAddressSpace *as, IOMMUNotifier *n)
 
         memory_region_notify_iommu_one(n, &event);
 
-        start += mask;
-        remain -= mask;
+        start += size;
+        remain -= size;
     }
 
     assert(!remain);