KVM: Fix x86 emulator writeback

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When the old value and new one are the same the emulator skips the
write; this is undesirable when the destination is a MMIO area and the
write shall be performed regardless of the previous value. This
optimization breaks e.g. a Linux guest APIC compiled without
X86_GOOD_APIC.

Remove the check and perform the writeback stage in the emulation unless
it's explicitly disabled (currently push and some 2 bytes instructions
may disable the writeback).

Signed-Off-By: Luca Tettamanti <kronos.it@gmail.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

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Luca Tettamanti 2007-06-19 22:41:20 +02:00 • committed by Avi Kivity

parent 74906345ff

commit 02c03a326a

1 changed files with 5 additions and 4 deletions

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9

drivers/kvm/x86_emulate.c

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