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authorHollis Blanchard <hollisb@us.ibm.com>2008-11-10 14:57:36 -0600
committerAvi Kivity <avi@redhat.com>2008-12-31 16:52:26 +0200
commitfe4e771d5c37f0949047faf95d16a512b21406bf (patch)
tree518b4ff17a8e1e62b747ce1912c08b62883d2855 /Documentation/filesystems/xip.txt
parentdf9b856c454e331bc394c80903fcdea19cae2a33 (diff)
KVM: ppc: fix userspace mapping invalidation on context switch
We used to defer invalidating userspace TLB entries until jumping out of the kernel. This was causing MMU weirdness most easily triggered by using a pipe in the guest, e.g. "dmesg | tail". I believe the problem was that after the guest kernel changed the PID (part of context switch), the old process's mappings were still present, and so copy_to_user() on the "return to new process" path ended up using stale mappings. Testing with large pages (64K) exposed the problem, probably because with 4K pages, pressure on the TLB faulted all process A's mappings out before the guest kernel could insert any for process B. Signed-off-by: Hollis Blanchard <hollisb@us.ibm.com> Signed-off-by: Avi Kivity <avi@redhat.com>
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