kernel -- x86_64: Do not set reserved bits in CR3.
authorAggelos Economopoulos <aggelos@dragonflybsd.org>
Mon, 20 May 2013 18:56:07 +0000 (20:56 +0200)
committerAggelos Economopoulos <aggelos@dragonflybsd.org>
Mon, 20 May 2013 18:56:07 +0000 (20:56 +0200)
commit5e73d5fc48f6c48d9a638404bfea3e7040601f8e
tree237bc9f1844195d3b5be9034c594313471aa8a31
parent5c778c08979b3c9eb0694da014793e06207f1e77
kernel -- x86_64: Do not set reserved bits in CR3.

The x86-64 platform code was setting PG_V, PG_U, and PG_RW bits in the
CR3 register. While the bits were supposed to cleared, Intel and AMD
hardware were ignoring them. Other x86-64 implementations, in
particular the software emulator in Linux's KVM, do check that these
reserved bits are zero.

Fixes issue running DragonFly x86_64 on KVM hosts without
two-dimensional (nested) paging.

Tested on a variety of real hardware (AMD FX(tm)-8150, c2q 6600, others)
and VM configurations (KVM on Intel/AMD hosts, Xen).

Committing-on-behalf-of: Venkatesh Srinivas <vsrinivas@ops101.org>
Reported-by: aggelos@, c.turner1, others.
Testing-by: aggelos@, swildner@, mneumann@, ftigeot@, profmakx@, Enjolras
Bug: 2561
sys/platform/pc64/x86_64/pmap.c
sys/platform/pc64/x86_64/vm_machdep.c