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qemu /
ec1a78cee97001b0ed25b5866e92dae058eb5877 intel_iommu: refine iotlb hash calculation
Commit 1b2b12376c8 ("intel-iommu: PASID support") takes PASID into
account when calculating iotlb hash like:
static guint vtd_iotlb_hash(gconstpointer v)
{
const struct vtd_iotlb_key *key = v;
return key->gfn | ((key->sid) << VTD_IOTLB_SID_SHIFT) |
(key->level) << VTD_IOTLB_LVL_SHIFT |
(key->pasid) << VTD_IOTLB_PASID_SHIFT;
}
This turns out to be problematic since:
- the shift will lose bits if not converting to uint64_t
- level should be off by one in order to fit into 2 bits
- VTD_IOTLB_PASID_SHIFT is 30 but PASID is 20 bits which will waste
some bits
- the hash result is uint64_t so we will lose bits when converting to
guint
So this patch fixes them by
- converting the keys into uint64_t before doing the shift
- off level by one to make it fit into two bits
- change the sid, lvl and pasid shift to 26, 42 and 44 in order to
take the full width of uint64_t
- perform an XOR to the top 32bit with the bottom 32bit for the final
result to fit guint
Fixes: Coverity CID 1508100
Fixes: 1b2b12376c8 ("intel-iommu: PASID support")
Signed-off-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20230412073510.7158-1-jasowang@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
2 files changed
