Parsing is simply using split twice. Data::Diver provides an easy means of storing the data in the appropriate place in the hash.

use Data::Diver qw( DiveVal );

my %hash;

while (<>) {
   chomp;
   my ($key, $val) = split(/=/, $_, 2);
   my @keys = split(/\./, $key);
   DiveVal(\%hash, map \$_, @keys) = $val;
}
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